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The Armourer View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote The Armourer Quote  Post ReplyReply Direct Link To This Post Posted: November 23 2019 at 1:05am
Originally posted by Long branch Long branch wrote:

Originally posted by Zed Zed wrote:

It would be interesting to see how a rifle with front locking lug's would fail. Would both lugs fail at the same time?
The long lug on the Enfield is an excellent safety measure for the shooter when it all goes wrong.

It would have been more interesting if they had examined the rifle a bit more before starting the shoot. I would like to have seen the bolt lug contact areas blued and tested. It is possible that if the small lug was taking more of the load, it may have initially started the crack over a long period of time.


He has another video in which he reads a passage from an original manual. It said that an oiled cartridge produced roughly twice as much force on the bolt as a dry one as measured by a crush guage.

The front locking actions tend to be a lot "meatier" than the enfield, so it would be hard to get a good comparison. I don't think that would really be relevant anyway. The point he's making is that the action is plenty strong for service cartridges.



It is interesting that when Ishapore produced the 2A (7.62) and they used 'improved steel' they found that during the proof testing that the action warped and the bolt locked up solid.

This happened with both the oiled-round and the dry round.
When they reverted back to the original steel (as specified for the No1 Mk3) the oiled round still warped the action but the dry-round was OK.
They amended the testing to 'drop' the oiled round test but never actually amended the test requirements.

This is why the 2A & 2A1 use the same steel as the No1 Mk3.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Long branch Quote  Post ReplyReply Direct Link To This Post Posted: November 23 2019 at 1:34am
Originally posted by The Armourer The Armourer wrote:


It is interesting that when Ishapore produced the 2A (7.62) and they used 'improved steel' they found that during the proof testing that the action warped and the bolt locked up solid.

This happened with both the oiled-round and the dry round.
When they reverted back to the original steel (as specified for the No1 Mk3) the oiled round still warped the action but the dry-round was OK.
They amended the testing to 'drop' the oiled round test but never actually amended the test requirements.

This is why the 2A & 2A1 use the same steel as the No1 Mk3.

I've never heard that. It was always my understanding that the heat treating process was improved. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote The Armourer Quote  Post ReplyReply Direct Link To This Post Posted: November 23 2019 at 2:50am
Originally posted by Long branch Long branch wrote:

Originally posted by The Armourer The Armourer wrote:


It is interesting that when Ishapore produced the 2A (7.62) and they used 'improved steel' they found that during the proof testing that the action warped and the bolt locked up solid.

This happened with both the oiled-round and the dry round.
When they reverted back to the original steel (as specified for the No1 Mk3) the oiled round still warped the action but the dry-round was OK.
They amended the testing to 'drop' the oiled round test but never actually amended the test requirements.

This is why the 2A & 2A1 use the same steel as the No1 Mk3.


I've never heard that. It was always my understanding that the heat treating process was improved. 


The old memory is slipping - the article states that with the 'correct'(original) steel the 2A stand up to both the oiled and dry tests.

An interesting article :

The article covers a host of subjects (and several pages) based around the Indian firearms industry and more specifically the ‘Proof House’, but of particular interest are a couple of paragraphs regarding ‘Enfield’s’.


Extract from “Gun Digest 33rd Anniversary 1979 Deluxe Edition”
Article Author : Mr A G Harrison
Qualification : Former ‘Proof Master’ of the ‘Rifle Factory Proof House, Ishapore, India’

From 1908 to 1950 all military bolt action rifles made at Ishapore were proof tested with a dry-round, followed with by an oiled proof round. The proof cartridge was loaded to 24 tons psi breech pressure, or 15% higher than the service pressure. In 1950 (after the departure, in 1949, of India from British control) the material for the rifle bodies was altered from an EN steel to SWES 48 steel with the recoil shoulder and cam recesses being heat treated. With this change the rifle receivers distorted when oiled proof cartridges were fired. This was discovered when hard and sometimes impossible bolt retraction was experienced. Large quantities of rifles were rejected.
To avoid rejections the authorities ordered discontinuance of the oiled proof round. Therefore from 1950 to the end of SMLE production, rifles made at Ishapore were proof tested with one dry proof only, although the specification still called for both dry and oiled proof. All bolts and bolt heads issued as spares were always proofed with a dry proof round only.

A bolt action rifle similar to the SMLE MkIII*, modified to fire the 7.62mm NATO cartridge, was produced at Ishapore, first in February 1965. The receivers were made of SWES 48 steel (as per the SMLE MkIII*) and with the NATO proof cartridge the receivers were found to distort with both the dry and oiled proof round. The material was changed back to the EN steel so now the rifles stand up better to dry and oiled proof. After passing proof the barrels are impressed with the Indian national proof stamp. The bolt handles and bolt head claws are struck with the crossed flags only.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote scottz63 Quote  Post ReplyReply Direct Link To This Post Posted: November 12 2021 at 6:32pm
Very interesting and informative video. Thanks! 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote W.R.Buchanan Quote  Post ReplyReply Direct Link To This Post Posted: June 19 2023 at 12:15pm
OK just a few thoughts here.  Saami Max PSI for .300 Win Mag with 180 gr bullets is 64,000 psi.

I thought they said  they were shooting 125g r bullets which would be considerably lower???.

Also I don't get the oiled round test. There is no way to quantify what the increase in Bolt Trust will be. If you are trying to blow the action up you won't know how much it took to do it.

One last question since I don't speak the Queens English very well. I didn't get that the barrel was a .308 barrel or a .313 barrel?  Obviously the pressure would be way lower if the barrel was .313 and it had .308 bullets going thru it, and it would hardly be a "Target Rifle," sights or not.. 

If it was a .313 barrel Then .312 bullets could be loaded into the .300 WM cases as reloads. However there ain't gonna be any factory ammo loaded like that.

My estimation of the action strength of these is around 55K psi Max.  I personally am not going to load either of mine past about 45,000 psi, just because I don't feel comfortable shooting anything more than that and there is nothing to be gained Ballisticly from a few thousand more PSI's. I also don't shoot my .308's or .30-06's much past about 53,000 psi and I don't shoot .300 Win Mags at all because I don't like getting the snot kicked out of me !

It has been my Experience that virtually all cartridges benefit "accuracy wise" from being reduced slightly from Max Loads. I don't have any MAX Loads in my inventory. It is a very rare thing that accuracy becomes better going past stated Max loads..

IMHO I think it is pointless to shoot anything less than 180 gr bullets at 2900fps in the .300WM or .300 H&H, since you are essentially shooting a more expensive .30-06 below those levels. It was designed to shoot heavier Bullets.(180,200,220gr) I have a friend who shoots his loaded with 240 gr bullets out to a mile and he is launching those 240 gr bullets at over 3000 fps. But he is very accustomed to the Recoil so it's all good..

I don't see any reason not to include this video as a Sticky as it is "Information," but I really don't see any Empirical Information as to what the yield strength of the action actually is?

It would be up to the viewer to decide what he has learned from it.

Randy
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: June 19 2023 at 1:39pm
Randy,

I didn’t catch what bullet weight they were shooting, 125 gr seems low for a .300 Win Mag, defeats the purpose of that cartridge.

The rifle is a 7.62 NATO conversion used in the Bisley “Target Rifle” (TR) class that was popular back in the late 1960’s and 1970’s.  It has a .300 bore and likely .308 groove diameter. 

The oiled cartridge is used in the British system of measuring breach pressures of ammunition. An axial piston is fitted into the breach of the test equipment that replaces the bolt.  A oiled cartridge is also used in proofing each action during production.  And yes, it significantly increases the bolt thrust loads, which is why the bolt lug failed on this rifle fairly quickly.  It would have survived many more rounds if they were fired dry. 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Long branch Quote  Post ReplyReply Direct Link To This Post Posted: June 19 2023 at 2:37pm
First, no, a 125 gr bullet would not produce significantly less pressure. It will simply move faster for the same pressure.

Second, while it may not be empirical, it shows that the action is not weak like many modern shooters believe. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: June 19 2023 at 3:45pm
^^^ This is correct.  

But, the No. 4 Lee Enfield action does not have the large strength margins that its contemporaries have like the Mauser and M1 actions.  I’d characterize the action strength as “adequate” and “fit for purpose”.  Part of this is due to the position of the locking lugs.  

For various reasons, I like to keep my handloads to within Mk 7 service cartridge pressures and velocities.  It’s difficult to know exactly what pressures the Mk 7 cartridge was loaded to because of the different pressure measuring systems used, but I expect they were loaded to under 45,000 CUP (US Radial Copper Crush method).  For the amount of shooting I do 41,000 CUP is a good practical limit to prolong the life of the action, so I select published mid range loads.  

It’s also a good idea to make sure the chamber is free of powder solvent and oil before firing.  This will help reduce bolt thrust and reduce case stretching. 




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Post Options Post Options   Thanks (0) Thanks(0)   Quote Long branch Quote  Post ReplyReply Direct Link To This Post Posted: June 19 2023 at 4:42pm
This reminds me of the myth that Damascus shotgun barrels are for black powder only.  In reality, many Damascus guns were nitro proofed later.

I forget the gentleman's name, but someone tested a number of Damascus guns to see what it would take to blow them up. What he found was that a homogenous steel barrel would withstand 3x the normal operating pressure of the round, while a Damascus gun would withstand 2x the normal pressure.  Yes, the Damascus barrel is weaker, but it still withstood double the pressure of any round you would put in it. He also found that they tended to "unwind" as opposed to bursting.

Yes, Enfield actions are weaker than Mausers. So are a lot of modern sporting actions. That doesn't mean they'll explode into 1,000 pieces if you hold them wrong, and all those .308 conversions aren't timebombs.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: June 19 2023 at 5:46pm
Originally posted by Long branch Long branch wrote:


That doesn't mean they'll explode into 1,000 pieces if you hold them wrong, and all those .308 conversions aren't timebombs.

Yup, I’ve got two of them.  But I load them to similar pressure levels as the .303 Mk 7 cartridge, otherwise brass life is short if you load to .308 Win (or 7.62 NATO) pressures.  

I’ve not come across any data that actually quantifies the ultimate strength of the No. 4 action (pressure that causes it to fail a one time application of load).   It’s likely north of 65,000 psi peak pressure.

The .300 Win Mag cartridge is about 10% larger in diameter at the base than the .308 and the .303, so would give 10%  higher bolt thrust loads at the same chamber pressure. 

Certainly, having healthy strength margin is a good thing as it mitigates risk with various screw ups that invariably occur during mass manufacture of rifle and ammunition, not to mention our own reloading errors that can and do happen.  The long successful history of the No. 4 has proven the design is sound. 
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Originally posted by Long branch Long branch wrote:

First, no, a 125 gr bullet would not produce significantly less pressure. It will simply move faster for the same pressure.

Second, while it may not be empirical, it shows that the action is not weak like many modern shooters believe. 

LB: I beg to differ with your assertion that a 125 gr bullet won't produce less pressure but more Velocity at the same pressure.

The 125 gr bullet has less Mass and less Bearing Surface therefore it requires less pressure to get it moving than a 150 or 180 gr bullet. 

Pressure can only build to a Specific Amount if there is Sufficient Resistance to build to that pressure. Peak Pressure for a given amount of Resistance is achieved a few Milliseconds after the charge is ignited and lasts for an amount of time relative to the Burn Rate of the Powder.. 

As the bullet accelerates the volume behind it increases  and as soon as the charge is consumed Pressure is Decreasing.

As soon as the bullet leaves the Muzzle it is decelerating, and headed down to the ground under Gravitational Pull.

In my Quest for loading data for my New 35-303 I found looking at Lyman 49 that Pressures for .358 Win. with 200 gr jacketed bullets and IMR 4895 powder,,, 49 gr.  produced  41,800 cup. Whereas with a 250 gr Jacketed bullet,,, 43 gr Produced  49,300 cup !  IE:  heavier bullet = more resistance and slower speed with more pressure.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Goosic Quote  Post ReplyReply Direct Link To This Post Posted: June 20 2023 at 2:56pm
W.R. Buchanan: I reload .308W  and .243W.  The 308 uses a 168grn BTHP and the 243 uses a 90grn BTHP. Using 35.5grns of VihtaVuori N540 for the 243 gives me a SAAMI PSI of 48,200 and pushes that 90grn projectile to 3200 fps.
Using 37.7grains of the VVN540 in the 308 gives me a PSI of 45,900 and it pushes that 168grn projectile to an averaged fps of  2455. The cases for both are identical until you get to the necks. The 90grn BTHP projectile uses 2.2grns less than that of the 168grn BTHP yet generates 2300 pounds per square inch more than the 308 while also moving 745 fps faster. IE: Heavier bullet = lower pressure and reduced speeds.  (You cannot overfill a 303 British case using black powder!)
For sh*ts and giggles i will fill 303 cases to the top with FFFG gun powder and then seat a 215grn RN on top of all that. Those bumble bee looking bullets will go no faster than 1875 fps and I had a pressure test done and the results averaged a SAAMI PSI of 35,750. Stuff a 174grn bullet on top of all that FFFG powder and the pressures can get right to the 45,000 PSI mark extremely fast...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: June 20 2023 at 3:47pm
Randy is correct in that with all other variables being equal, the heavier bullet will result in higher peak pressures.  The key, of course, is that ALL other parameters of the load must be identical except the bullet weight.  That includes case volume behind the bullet.  Many other factors can result in pressure differences. 

It is indeed possible to overload a cartridge with light bullets.  If you look at reloading tables, you will see that max charges increase as the bullet weight decreases.  This is because of the reasons Randy explained.  Some calibers may not have the case volume needed to contain sufficient powder to produce maximum rated pressures for very light bullets with some powders.  .30-06 is not one of those.  You can indeed overload a .30-06 case with typical rifle powders with a 125 grain bullet (i.e. exceed the max safe pressure for that cartridge). 

My .30-06 short range match load uses a 125 grain flat based bullet.  I use this bullet for two reasons: it is very accurate and the recoil is very mild so it will not knock you out of position when shooting the rapid stages.  That little bullet can be loaded to very high velocity within safe chamber pressures.  But, I load it to only 2800 fps for the reasons explained above with 44.5 gr H4895.  That’s actually classed as a “reduced load”, as it is below the published starting load for H4895 powder.  Hodgdon website gives a max charge of 53.7 gr at a pressure of 49,300 CUP, so right about at max pressure for the .30-06.  So, don’t be fooled into thinking you can’t exceed cartridge max pressures if you use light bullets. 

We have wandered off topic here, but interesting discussion nevertheless. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote A square 10 Quote  Post ReplyReply Direct Link To This Post Posted: June 20 2023 at 4:10pm
back on to the original post - does any data exist for the pakistani no4 rifles in 762x51 ? those would more relate to the topic but then im not the guy in this conversation obviously , i love all the discussions and appreciate all the info [most of which ill never apply but i love learning new things] it seems to me that the canadians should have data as well as they produced a lot of 762 conversions - the chanwood i had jumps to mind - i loved the rifle but it hated 308 - the 762 worked fine in it so there may well have been a very tight tolerance for the cartridge pressures , 

ill bow out now as i have nothing of value to contribute to this discussion beyond that , i do enjoy reading these posts tho , i like learning something every day ...."adds to my storing up smarts so festus said once in an episode to gunsmoke  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: June 20 2023 at 4:31pm
ASquare, I’ve not come across any data that quantifies the ultimate strength of the No. 4 action, or the No. 1 Ishapore action used for the 2A 7.62 for that matter.  This thread attempts to qualitatively show that the No. 4 action it is indeed strong enough (at least for a limited number of rounds) to sustain the loads from a significantly more powerful cartridge (.300 Win Mag) that also has a larger case head diameter than the .308, and with the cases oiled, produce much higher bolt thrust loads than dry .303 ammunition would ever produce. 

We really don’t know how many 7.62 NATO rounds have been safely fired in converted No. 4 actions, but I suspect it is in the millions. These rifles that were officially converted went thru proof testing to show they met the strength requirements in place at the time the conversions were done.  These rifles were used extensively in Britain and Canada (and in other commonwealth nations) in service rifle matches for many years.  I have shot several hundred rounds of Canadian 7.62 ball service cartridges thru my conversion with no concerns at all.  But, in the interests of being a good steward of an increasingly rare rifle, I choose to handload to mild pressure levels, a bit less than .303 Mk 7 pressures. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote A square 10 Quote  Post ReplyReply Direct Link To This Post Posted: June 20 2023 at 5:25pm
indians [dots not feathers] used the no1 in the conversion , the pakis had the no4 equipment thanks to the brits i might add , i know of no published data either , just thought maybe someone else might be better edumacated than i am , 
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