About 10,000 rounds thru the barrel, I wished I had kept a barrel log. It was a very good shooter indeed. But groups had opened up from the 1 to 1.5 MOA range to 3 to 4 MOA and no longer would hold the 10 ring on the US NRA Short Range target. Gone were the days I could put ten consecutive shots into the X ring at 200 yds shooting prone with the standard Mk 1 aperture sight. 

I purchased a Criterion barrel several years back with intentions of using it on this rifle when the barrel went. Last Friday shooting it at the range convinced me it was time. 

BSA barrel removed this morning. This one came off fairly easily. I use a 3 foot steel pipe extension on the action body wrench. Did not have to use heat on this one, nor cut the barrel reinforce either to relieve the compression on the shoulder.

Cleaned the action body in the ultrasonic cleaner, solution was black when it finished. Took out years of crud. 

The new Criterion barrel, a 5 groove LH twist, .3025 bore.  174 gr SMK contacts lands at 3.098 OAL with Hornady OAL gage.  The thinnest breeching up washer (.037 thick) gives 14 deg barrel under turn. 

It’s ready to install. Hand tight headspace looks good. Here is the bolt position with the .070 No-Go gage and the #1 bolt head that was on the bolt. 

Still have to finish ream the chamber, but it’s pretty close as it is, just a very light cut until the reamer just contacts the back face of the breach.  Headspace and cartridge base to ogive measurements retaken with 174 SMK after finish ream and barrel install. 

I'm curious as to what brand of finish reamer you have.

I have a Clymer and the pilot's not even close to fitting the bore of two new SMLE barrels I have.

I used it on a no 4 barrel that I repurposed for a project rifle and now I have to get it ground before finishing the others up.

I’ll post more photos once I install the barrel. I finished reamed the chamber this afternoon. I did this with the barrel off the action. This always makes me nervous, as you can mess up the throat this way. I borescoped it afterwards and it looks good. Hopefully I did not bugger it up. 

The biggest problem I have had is getting the old barrel off.  These barrels are on tight. Finding a workable action wrench and barrel vice took me a while. The set I have seems to work, but it required a lot of sanding to get the tapered aluminum barrel vice bushing to fit the chamber reinforce. Despite being advertised as a Lee Enfield action wrench and barrel vice, the fit to the chamber reinforce was all wrong giving only a line contact.  I ended up wrapping an old barrel I had with sandpaper around the reinforce and chucking it in the drill press.  Then holding the bushing down over the sandpaper to get the right taper.  Even then, the barrel wants to spin in the vice, you have to put a lot of torque on the two bolts that clamp on to the barrel.  

One thing I don’t really like about the action wrench is that it relies on clamping forces as well, and it clamps right on the forward part of the action body over the threaded area. This must be squeezing the body down onto the barrel threads, which just makes it harder to turn. I wish I had drawings of the original action wrenches and barrel vice.  I thought about sending the barreled action off to Brian d**k to separate for me but I decided I didn’t want to put it in the mail. 

It’s much easier installing the barrel. The Criterion barrel comes with a set of breeching washers of four thicknesses in increments of .001 inch. The thinnest one seems to be the right one giving a 14 deg barrel under turn before applying any torque. The next size gave about 20 deg which I think is excessive.  My measurements of under turn are fairly approximate using an adjustable protractor held on the knocks form flat and movable arm held vertical to the body. 

I probably won’t get anymore work done on it until Thursday. 

What Ive done in the past, is mark each side of the block onto the barrel with a #2 or grease pencil and carefully file but using a small triangular file.

Ive also used a hacksaw when doing pinning and carefully on other systems opening up the cut with needle files. Like one would do when making a dovetail.

If its done this way, the edge of the cut can be peened over to tighten up on the pin if necessary.

A trick associated with using a hacksaw blade is to grind one side of the teeth off. That way you can control the width of the cut and keep the cut straight. This is a good method for fixing buggered screw heads that are just peened over and dressed off nice and smooth again.

As for how it was done originally I always assumed it was done primarily by hand fitting on initial assembly. 

The reason for my thinking is, sometimes when swapping barrels stocks and what have you, the block for the sight will interfere with the front of the stock and the sheet-metal bands that reinforce it.

Often theirs not much room to work there if the original slot has been cut because of the diameter of the pin and how distorted they become.

For this reason I would assemble the fore-end to make sure the block is positioned correctly. Every once in a while one will need moved front a touch. The good news is, the lugs on the barrel will keep the block straight and keep it from wiggling left and right when you file. Just make adequate clearance to the stock is available.

I use the attached fore sight block (a clean machined one) to index the barrel with levels once its coming up to tight and then you can check it on a heavy piece of glass or a scrap of that ground granite they cut for counter tops by turning the barrel over to the block and the sight ears on the make do surface plate. Sometimes yo need to lever them a little bit to get them just so.

First, get the barrel leveled in the barrel vice. Unfortunately, can’t use the flat on the Knox Form as it is hidden under the vice bushing. I use a spirit level along the top of the front sight block band.

Barrel clamped up very snug, using a 2 foot ratchet and socket on the vice bolts. Powdered rosin on the reinforce and both surfaces of the aluminum bushing and the inside surface of the barrel vice.  Anti-seize lubricant on the barrel threads. Action wrench aluminum bushing also dusted with powdered rosin and pushed over front threaded area of the body. 

Measured the body under-turn at 15 degrees when snugged by hand.  Reynolds stated 18 deg was the requirement, but during wartime production, this varied a lot. The next size up breeching washer would put the underturn at over 20 deg, so I used the thinnest washer, 0.037 inches thick. 

Action wrench fitted and bolts torqued, not as tight as barrel vice, not putting nearly the torque on the wrench to install the barrel as it took to remove it. 

Torque action body to barrel until it is level with the front sight. I use a close fitting drill bit thru the back sight ears. The final tweak to align the body took about 100 foot lbs, an estimate, not using a torque wrench here. Had one foot up against the bench leg and gave it a good pull. 

Action wrench and barreled action body removed from the barrel vice. You can see the two aluminum bushings here.

Headspace checked. With two layers of aluminum foil (.0013 thick total) the bolt just closes on the 0.064 GO gage, so headspace is a fraction over 0.065 inches with the same #1 bolt head, just where I want it. Bolt a long way off locking on the 0.070 NOGO gage.

All done…

Torquing the barrel higher than I did makes it that much harder to remove. I don’t think I was anywhere near yielding any material, but with the next size washer, I might not get that barrel off. The barrel I removed had about the same underturn angle, and it was tough to get off, took about 80 lbs at a 4 foot lever arm (320 ftlbs).  The last barrel I did had about 12 degrees underturn, and it shot well. 

Page 185 of Reynolds book states the No. 1 and No. 4 drawing requirement for the breeching up angle was 10 to 14 degrees. For some time, this angle was substantially lower for the No. 4 in practice. The issue was studied and the final desired angle was 18 deg which was to give a standard breeching “load” of 120 lbs +/- 5 lbs. I presume he meant foot pounds of torque and not pounds force, unless the load is associated with the specific tooling used. I concluded 15 degrees should be satisfactory. 

I’ll look carefully at the bedding. I may leave it alone. Fulton’s did a first rate job of it back in 1963. Although years ago when I first removed the forend, I was not aware of exactly how to remove it. I do remember it being a very tight fit. Looking closely at the wood draws, I see some slight compression. If the rifle still won’t shoot well with the new barrel, I’ll consider repairing it. 

Impressive job by the way! looking forward to the range reports!

Like that idea Shaun! That’s exactly what I will do, I’ve got several spare block bands. Thank you for that suggestion.

I should get the rifle reassembled soon after the 3/32 dia. file arrives.  Hope to get it to the range next Friday, weather permitting. 

Using Zed’s great suggestion, taking a snug fitting spare block band, I opened up the hole for the retaining pin to 7/64 inch, a very slight enlargement. I then used the 3/32 file to slot the band upwards away from the barrel.

That allowed the 3/32 file to slip in the modified band above the barrel.  Careful filing of the barrel with light downwards pressure using the band to locate the notch needed in the barrel for the tapered pin.

Remove the slotted band, install the original band and trial fit the tapered pin. Repeat as required until the pin was a nice tight fit. 

Hope to break in the new barrel and shoot a few test groups on Thursday. 

I once failed a rifle inspection prior to the match, so decided I had to get this device, it’s identical to the one the CMP uses for match inspections. 

The trigger weight gauge is similar to what the French use for our service rifles. My rifles are well over the minimum. But it's the feel and regularity of the trigger that I like. 

luv your breaching up tools, allows little or no stress to the action body.

Great tutorial thanx for posting.

It's pouring rain here in ATL today, but Thursday forecast looks good; hope to get out to the range. Will post the results of the break in and test firing. 

I`ll second that

Stickum applied.

The process I use is:

1) Fire one shot and clean, repeat as many times as necessary until copper fouling begins to reduce. Typically 5 to 10 shots. 

2) Fire three shot strings and clean, repeat two or three times until you see more reduction in copper fouling.

3) Fire five shot strings and clean, repeat two or three times until you see little fouling. 

4) Fire 10 shot string and clean. Break in is done. 

I was able to do this today with 40 rounds.  

I cleaned with Bore Tech Eliminator, it is easy to tell if there is significant copper fouling as the patch turns blue. Dark blue is heavy fouling. The first patch comes out black and is the powder fouling, second patch (and third) will be blue.  Once the third patch comes out with only light blue streaking, you know you’re close. 

I’ll need to tighten the barrel another 3 degrees.  The first shot went left approx 7 minutes. This is the first time I’ve had that problem. On the five barrel installations I’ve done, the first shot has always been within a minute or two of center.  Also, the elevation changed considerably, by 9 minutes (low). I don’t have an explanation for this.  I’m going to measure the pressure at the forend barrel bearing (this rifle is center bedded at 5 inches forward of the chamber). 

Once I fiddled with the sights, it started to put rounds in the x ring (200 yards), so I think this barrel is going to shoot.  This was the first 9 rounds, which I cleaned the bore between each shot with Eliminator. 

Then with a close fitting drill bit thru the rear sight axis pin ears the barrel was indeed under torqued, by about 2 to 3 degrees. Just one degree of under turn results in a 2 MOA lateral shift (to the left) in the MPI. 

Nipped up the action body a small amount at a time until the barrel and body were level. 

Now to test for groups…

Enjoying your thread and updates; looking forward to seeing how it shoots in competition.

Skies were clear.  This range faces south, which is the worst direction for this time of year on a clear day. The sun shines right on the firing point, and in the winter, the sun is more to the south so shines in your face. The targets are in the shade. I’m finding these lighting conditions harder every year to get a good sight picture. I far prefer to shoot on a cloudy day. 

Tweaking the barrel indexing helped, but it still shoots a bit to the left.  First five shots with the front sight centered.  200 yards prone in the sling. Held good waterline, about 1 MOA vertical spread. 

Adjusting the front sight and shot 10 rounds. I’ve zoomed into the 9 ring here for this photo. I called shot #5 to the right, that was all on me. Shot 8 and 9 was my attempt to hold slightly low as the previous 7 shots were grouping a bit high, over corrected. 

It looks like this barrel is going to shoot, five of these 10 shots are within 1/2 MOA. 

I’m going to widen the front sight by fixing .020 inch thick sheet brass to each side of the front sight blade with epoxy. I need all the help I can get, my vision is deteriorating. I found it nearly impossible to get a clear sight picture today. 

We need to speak! 

I now have 225 rounds thru the new Criterion barrel.  It’s not settling down, groups have been opening up. It will shoot perhaps 5 rounds just over 1 MOA, then throws fliers.  Many times, the first shots out of a cold bore land 3 MOA high and left. 

Some groups are terrible, over 4 MOA. It’s not good enough for shooting the 200 yd vintage matches.

 Looking thru the 18 target plot sheets of ten shot groups, the best was 2.1 MOA. That is respectable shooting prone with the Mk 1 service sight, but not 4 to 5 MOA. It’s just inconsistent and not what I expect from a new barrel. It seems to “want to shoot” but something is just on the edge regarding bullet stability. 

I don’t know what the problem is. I suspect it might have been the chamber finish reamer. This extended the throat considerably resulting in a bullet jump to the lands of 0.305 inches (174 gr SMK seated to 3.05 inches OAL). 

The first thing I noticed with the barrel was the significant change in POI on the target. About 8 MOA low and 7 MOA left. I reindexed the barrel past vertical and still a lot of left drift on the foresight blade. Never had this kind of issue before with barrel replacement. 

Thinking the worst, that I had somehow distorted the action body removing the BSA barrel, I decided to remove the Criterion barrel and reinstall the old BSA barrel I had removed. This barrel has upwards of 10,000 rounds thru it and the borescope pictures look like it does.  Indexing this barrel back to where it was by using a spirit level on the foresight block band and rear sight axis pin holes, my first shots on target were right where they should be. And it shot well for the first 5 shots. Groups did open up as expected, but it was nowhere near as bad as the new Criterion barrel, 2 to 3 MOA. 

First 5 shots just over 1 MOA. 

Three ten shot groups fired for score were 98-2x, 99-1X and 100-3x. About what it was shooting before I removed it, probably a bit better.  Not what it once was, but after 10,000 rounds, that’s still pretty decent. 

I talked to Criterion about this and they sent me a new barrel free of charge. I’m impressed with their customer service. So, this next barrel will not get touched by the chamber reamer. It is supposed to be short chambered by 0.01 inches, but SAAMI specs for .303 British chamber are likely similar to military specs and these chambers are typically reamed long to account for wide dimensional tolerance in ammunition and mud/dirt in the battlefield. Well, I don’t intend to shoot this in the trenches nor load old military ammo that may be a bit long. 

I did check several Canadian Mk 7z rounds, and they drop freely into the chamber right to the base of the rim. I also checked the throat length with my Hornady OAL gage, a 174 gr SMK touches the lands at 3.098 inches (giving a jump of 0.048 inches when seated to 3.05 inches). A 2.225 inch long case drops into the rim freely, so the chamber is long enough “as is”. 

Borescope reveals nicely cut lands in the throat area, much nicer than what they looked like on the first Criterion barrel after finish reaming.

So, I can’t see any reason to put a reamer in this barrel. I’ll install it as is, headspace it by picking an appropriate bolt head, and break this barrel in.  Hoping for a much better result. 

One time I re-barreled a p14 with a CBI barrel and never used a finish reamer. Its a totally differing system to a No 4 but still 303, so I get it.

Every, CBI barrel that was installed bar none has been supplied with a larger diameter throughout the entire contour so adjustments to the bedding were necessary when fitting.

Ive re-barreled, Garands, Krags, M17-14's and both variants of the 06 Springfields.

I think particularly with the rimmed cartridges, and this is true with the Krag barrels especially, because the pilot of the reamer where it enters the bore is such a larger diameter than what otherwise would be the throat and the diameter of the reamer that cuts the throat is smaller is where a certain amount of accuracy degradation occurs at least in that chamber and the tooling I have available to me.

If I cut the chamber with a dummy cartridge as a gauge to where the bolt just closes but allows the cartridge to be easily extracted is where I notice the tipping off point is,so its close. 

If I finish for the cartridge to free itself of the chamber and to fall easily from it there is a big difference in potential loss for accuracy becuase of the additional space introduced by removing the additional chamber material not just from the throat but from the radial dimension of the chamber as well so my best estimate is there is an additive condition when finishing to the latter instead of the former.

Another constant has always remained true for me and that is if it shoots left, needs more heft as the adage goes especially for Garands but evidently the rule can be applied to other systems as well based on your findings with the spirit level images you captured.

Using that method has had me going more than one time and second guessing myself so what i did was save a fore sight protector that's in new shape, check with levels but then invert the whole thing for a no 4 upside down on a nice true piece of granite to gain some additional perspective based on what the levels and extractor slots are doing.

A counter top maker usually will have some nice slabs available from the cut off pile that could be useful for that sort of thing for free often in an array of colors but I like the white or light grey pieces.

Glad to hear they will be sending another barrel. I did a Krag carbine last week and the owner was able to source his but only after a long wait.

The barrel did headspace perfectly, 0.0640+ inches using the same bolt head. If it was too short even with a #0 bolt head, then I would have to ream it, but hopefully not necessary with this second CBI barrel (which I already have now). 

I have rebarreled two M1’s and windage was dead on center using a spirit level to index the barrel and front and rear sights set to mechanical zero. Not on this first CBI barrel…foresight blade was all the way to the left such that the right side of the base of the blade was flush with the front sight block band. Not a good sight picture. 

The CBI barrels are made from AISI 4150 chrome moly steel, fairly common barrel steel. Not sure what was used to make the original barrels. Might be in Reynolds book. 

The higher velocity would indicate that there is less surface friction to contend with during bullet to rifling contact which in and of itself would suggest that the rifling in the Criterion made barrel is not cut to the same standards as the BSA barrel.

The CBI barrel has the exact same rifling dimensions of the BSA barrel (when it was new). Equal width of lands and grooves, 5 groove, 0.3025 bore. 

Here is what the bore of the BSA barrel looks like, about 1 inch forward of the chamber, after a good clean with Eliminator, C4 and then JB.  Barely any perceptible rifling.  Surface flakes of steel are coming off in places from the firecracking, second photo about 2 inches down the bore. It’s surprising it shoots as good as it does. 

#1: I have doubts that the rifling was cut to the same exacting standards as that of the British Ministry of Defense's "Standards."

#2: It is not surprising to me given that the barrel steel has been, "Work Hardened."

You finish reamed the chamber but, I highly doubt that is the reason for the barrels inconsistencies in accuracy.

It is my opinion that Criterion sent you a subpar rifle barrel.

That gave me a cynical smile Goosic; especially when remembering talking to a squaddie way back in 2000 during a service rifle meeting; he had two firing pins (SA80) break on him in the same competition.

Has anybody read the story of the L96 sniper rifle?

The MOD contractor(Pylon Industries) was so clueless they were putting a radius on the bolt lugs. 

Dave Walls who designed the L96 walked into the boardroom with a finished rifle and put pushed a cleaning rod down the barrel...the bolt flew open!

Although I will concede that BSA generally produced quality goods back in the day. 

 

By the way, the CBI barrel is button rifled, not cut grooves. It looks very good with the borescope. I’ve had several CBI barrels in .30-06 and .223 and they shot very good indeed. But so far, I’m 1:1 bad with the CBI No. 4 barrel. Will see what the second one does. 

The tolerances in original No. 4 barrel production were quite large, particularly in regards to bore and groove diameter. The CBI barrel is a .3030- bore and .314 groove (depth of rifling 0.0055), well within allowable tolerances for No. 4 barrel production and represents about the mean dimensions of No. 4 production. 

I wouldn't  characterize No. 4 barrel rifling as “exacting standards”, the tolerances were quite large so that barrels could pass inspection and reduce the rejection rate. In post war production, these tolerances were tightened up somewhat.  Interestingly enough, the rifling dimensions of all of my No. 4 barrels are right on par with CBI, .3030- bore and .3140 groove. This is based on slugging the barrel with a soft lead bullet. But, these No. 4 barrels are all post-war production from Fazakerley and BSA as the rifles went thru a FTR and conversion to Mk 1/2 and 1/3. 

(The "Leade" is the critical area where accuracy can be negatively affected  if improperly cut.)

Yup, that’s what I said.  The throat actually includes any length of freebore and the tapered rifling leade.  And I suspect the throat has been improperly cut by my chamber finish reamer. The chamber finish reamer cuts not only the chamber, but the angle/length of the throat (leade).  The chamber reamer lengthened the throat considerably to the touch point of the bullet, over 0.13 inches longer. Which is why I think it was defective. 

Theoretically, the throat length to the touch point (approx .3104 diameter for .3114 dia SMK) should have only been 0.01 inches short from CBI, and as measured.  As measured with the Hornady gage, the SMK had a  0.048 inch jump to the lands when seated to 3.05 in OAL as I received the barrel. Pretty darn good right there. After reaming, that increase the jump to 0.182 inches. At best, this took a lot of barrel life away, at worst, it kills accuracy. 

As it came from CBI, it looked quite good, yes there was reamer marks, but that’s unavoidable and the purpose of breaking in a barrel to burnish the leade in. After finish reaming, it looked much rougher and some gouge marks. That was a brand new reamer too. 

I’ll report back the results with the second new CBI barrel, hope to get out to the range on Friday. 

A few small nicks where the reamer pilot touched/scratched the lands, but otherwise looks quite good. 

Note that the .303 really has no “freebore”. The rifling leade (really, spelled “lead” but sounds like “leade”) begins right at the forward end of the chamber. You can see that on the SAAMI chamber drawing and in these borescope pics. 

Here is the very end of the chamber, if you look around the outer edges of this photo you see the step from the case neck area onto the bore rifling. No length of freebore at all. The diameter at the origin of rifling (shallow as it is) is 0.3131 inches, a hair under full groove diameter. You can see the lightest of reamer marks in the groove just ahead of the chamber neck area. Then the first section of throat taper begins, followed by a slightly more shallow taper onto the full bore diameter.  

Part way down the throat:

Here is the forward end of the throat. The reamer just touching the lands here at the full bore diameter of .3025 ish. 

As a co-worker used to say to me, Geoff, this is way more information that you need to know!  On the flip side of that, I’ve learned from 40+ years in aviation structural engineering that the “devil is in the details”. 

Maybe the problem is with the breeching washer.

.037 is pretty thin, maybe a washer that is thicker and the correct amount removed from the barrel tenon so that underturn is correct could work out better.

If you didn't have to send the old barrel back, or they didn't request for it, that one could be used for a test case.

The washers that were supplied, did they appear above the knox when the barrel was tightened or were they not so tall as they could be seen?

CBI did not ask for the barrel back, they just sent me a new one. I’ve put that barrel aside. But at some point, I can certainly try breeching up with the .038 washer.  I suppose the shoulder could be machined back the thickness of a full turn and chamber re-cut carefully. 

Yes, the washer does protrude above the Knox, I think it matches the OD of the chamber reinforce IIRC. 

This 2nd CBI barrel indexes at 15 deg underturn with the .040 (thickest) breeching washer whereas the 1st  CBI barrel indexed at 14 deg with the .037 thinnest washer. That’s going to lengthen headspace somewhat, but still well under 0.070 just in the hand snug position. 

Got to put a small chamfer at the back lower edge of the chamber to keep bullet tips from getting caught, then ready to breech up the new barrel. 

Despite the thickest breeching washer being used, headspace came in very tight.  A sliver too tight. I’m using the shortest bolt head I have, a #0 that measures 0.629 inches. The bolt is touching the .064 gage just before the bolt handle contacts the action body wrist. 

Here is the bolt handle position without the gage:

And with the .064 GO gage, note the sliver of light between the bolt handle and top right corner of action body wrist. 

Not sure what I will do with this yet. There is no problem fully locking the bolt on cartridge cases, as it is very rare to get one with a .064 inch thick rim.  The options would be to grind .001 off the bolt face, hoping I keep it flat, find a shorter bolt head or ream the chamber.  I may just leave it alone. 

I also slugged the bore, the grooves are right at 0.313-0.314. It’s not a precise measurement as you have to roll the bullet between calipers with five groove rifling. It’s likely 0.3135.  The thin jacketed 174 SMK has no trouble upsetting to fill the grooves of that depth. 

Shot four 10 shot groups with the rebarreled Long Branch Mk 1/3, this is with the second CBI barrel.  All groups shot prone unsupported at 200 yards with sling and standard Mk 1 aperture rear sight. 

Each group got progressively better.  This is with a slightly increased powder charge from my long standing Match load of 40.0 gr Varget, 174 gr Sierra MatchKing. This load is 40.6 grains that I arrived at via an Optimal Charge Weight ladder test on the No. 4(T). 

Group # / Group Size (MOA) / Score / Mean Velocity (fps) / Standard Deviation (fps)

  1 / 3.26 /   99-3x / 2405 / 34

  2 / 3.11 /   99-3x / 2410 / 20

  3 / 2.91 /   99-2x / 2427 / 18

  4 / 2.82 / 100-2x / 2425 / 13

Note that the velocity standard deviation reduced with increasing round count. Perhaps the barrel is still breaking in, smoothing the lands.  I am definitely out of practice shooting with iron sights (I’ve been concentrating on shooting in the modern Service Rifle (High Power) matches for the last few years). I expect with some additional practice and rounds down the barrel the groups will shrink to around 2 MOA on average. 

Here is group #4:  

Had to fiddle with the front sight to bring the group onto target center, just very slight adjustments which I overshot a few times. Once I completed shooting the four 10 shoot groups I made one final adjustment and took three sighters to be sure I had a solid 200 yard zero:

The three shots fell at just over 1 MOA and in the X Ring. Good with that…

I’m very pleased with this result.  More than satisfactory for CMP Vintage Military Rifle Matches. 

If you do decide to fit a CBI barrel, give serious consideration to NOT finish reaming the chamber. It comes 0.01 inches short, but the .303 chambers are notoriously long to accommodate dirt and a wide variance in cartridge dimensions. Handloading gives you control over this and essentially as received is a “match” chamber and close to minimum throat length which will prolong barrel life. 

Hopefully this barrel will be good for at least 3,000 rounds, perhaps as much as 5,000 rounds. It is button rifled, so I don’t expect much more that. 

I'm staggered by how well you and that barrel shoot, well done! 

Same thing with Frenchie. An eighty year old rifle that still has a couple hundred round to get through it before it is fully broken in. Groups are definitely getting smaller...

 So far, 85 rounds thru the barrel. It does seem to be settling down.  I found it interesting to see how the mean velocities increased, standard deviations decreased and group size decreased over these last 40 rounds. 

My routine cleaning will be with Hoppes 9, cleaning twice a day for a few days, I’ll watch for any build up of copper and carbon in the bore and clean accordingly. 

well done!

The length from case head to the shoulder datum is 1.817 inches (Hornady Case Headspace Comparator).  The case above that in the photo is a new PPU case. It is also 1.817 inches.  I measured about 10 PPU cases and they are quite consistent in this dimension. 

A fired case in this barrel (which came 0.010 inch short to SAAMI specs) measures 1.839 inches. That gives the cartridge case over 0.020 inch clearance at the shoulder. An additional final finish ream would increase that clearance to 0.030.  What you really want for accuracy is zero clearance, or even a 0.001 interference (crush) for accuracy. For reliable rapid fire feeding, I like to have at least 0.001 clearance. 

Now, the other important dimension is the actual chamber length to the case mouth. That’s harder to measure without taking a chamber casting. But, what I did do is chamber a series of empty cases of varying lengths to see if there was any resistance to bolt locking and any tendency of the case mouth to ride into the step down into the throat. I checked this with pin gages to look for the case mouth closing up. 

The chamber minimum length should be 2.222 from breech face to front of chamber.   With a case as long as 2.229, the case mouth was still not deformed when it was fully chambered (bolt locked). 

The third check was to determine the cartridge OAL when the bullet touches the lands. Using a Hornady OAL Gage, the 174 Sierra MatchKing touched the lands at 3.098 inches, which is 0.023 beyond maximum cartridge length (3.075). 

With all of the above and a correct size bolt head to get the rifle to headspace within specification, I felt there was no need to ream this chamber. 

Thank you Shaun. It did not go as easy as expected, nor did I get the results I was expecting the first time.  But I’m glad I stuck with it. 

I really appreciate CBI stepping up and replacing that first barrel at no charge. And they did it just based on my measurements of the throat length with the Hornady OAL gage. They knew it would not shoot with a throat that long. 

I do need to get back with Manson to figure out what was wrong with that brand new reamer. 

Next Saturday is my first competition since last June. I have not shot at 200 metres since then; so just fired a few rounds at 50 metres a couple of weeks ago. Working out the impact over point of aim variations for different distance. Hopefully it shouldn't be too far off; with final adjustments during the 5 test shots. 

The CBI barrels come 0.01 inches short chambered. Theoretically, you need to get a finish reamer to cut the chamber to full depth. That’s what I did on my first CBI barrel. But if you read this entire thread, it did not work out too well for me, resulting in an overly long throat. So, CBI sent me another barrel, free of charge.  Outstanding customer service. The second barrel, I did not finish ream.  As you probably know, this finish ream has nothing to do with headspace as that can be set by selecting an appropriate bolt head. LE chambers are quite long to the shoulder compared to factory cases and cartridges and I found that Mk 7 ammunition and new PPU cases dropped all the way into the rim as the barrel came from CBI. 

Cases extracted easily and fairly minimum expansion. I’ve neck sized them a few times, think I have about 200 rounds thru the new barrel now. Very happy with the results, a very accurate barrel indeed. 

As this barrel breaks in, mean velocity is climbing and group center to center extreme spread is shrinking. Here is todays result prone at 200 yards, first group was slow fire and second was rapid fire:

Gp   MV    ES     SD     C-C     Score

 #   (fps) (fps)  (fps)  (MOA) 

  1   2452  53    15.5   2.5     100-4x

  2   2426  62    15.8   2.5     100-7x

Standard match load:  PPU Case, WLR Primer, 40.0 gr Varget, 174 gr SMK, 3.05” OAL

Here is the prone rapid fire group: 

I’m very impressed with the Criterion barrels. And excellent customer service as well. 

I’m really looking forward to getting back in the groove shooting the “wood guns” in vintage service rifle matches. Taking a break from the AR for a while. 

I'm with you on both points there Geoff; and yes that's a stunning group! 

Lothar Walther have a good reputation in the UK although I'm not sure I have seen one on an Enfield over here. 

I’ve got one of these barrels, and I thought it was made here in the US, but might be wrong on that.  Not installed it yet. I may use it on the No. 4 T. 

That's a group to be proud of, mate!

From what I'm able to discover they are in Cummings, Ga, USA?

The CBI barrel bore is quite nice, and no question it shoots. 

I did find out that the Lothar Walther barrel was made in the US, there is a US barrel production facility not far from where I live. They shipped it direct to me.  Probably should have bought two of them. 

Correct, you beat me to it Shamu. 

Ideallly I'd like to get a Criterion .30 1/10 blank, have it turned to the L39/L42 barrel profile.

I still haven’t opened the box that the Lothar Walther barrel came in.  But, I’m fairly certain they are button rifled, 4 groove.  

I don’t see the No. 4 barrel anymore on the Lothar Walther website. 

I opened up the box that my Lothar Walther barrel was shipped in, weighed and borescoped the barrel. Here is what I found:

Barrel weighs 2 lb 8.75 oz. That’s about right on spec.

Rifling is 4 groove, RH Twist. Grooves appear to be a bit wider than the lands and are square edged.

The bore and the throat has obviously been hand lapped to a very good finish. I would not put a reamer in this chamber either. 

Photo below is at the front of the chamber, bottom portion is the end of case neck annd top portion the origin of the rifling. 

This photo of the throat, just slightly forward of the previous photo: