This should be a sticky, I think. I'm tired of hearing how weak the enfield action is. Here's a stress test on a No.4 enfield chambered in 300 Win Mag.

What says the Hive mind? Sticky or not?

My take away is that it lasted many decades firing 303 with that flaw. Then, it lasted a while in 7.62, which is a higher pressure cartridge. Then, it took 16 rounds of .300 win mag, 6 of them slathered in oil, to finally cause the already flawed bolt lug to break. Even then, that's not an action failure. The headspace did not shift throughout the test, which means that the receiver held up spectacularly. I wonder if it would have broken at all had the bolt not already been cracked.

 

Doesn't worry me though, shows that the action design is fail-safe with the long continuous locking lug. 

 

Goes to show that the No. 4 is perfectly safe to shoot 7.62 despite "warnings" that are out there.  

 

Bottom line:  Keep the chambers free of oil and keep the cartridges dry and bolt thrust loads are greatly reduced giving longer life.

Testing to destruction is just that.

I can't believe thats a £50 rifle!

ARGHHHHHH!

I know!

At those prices I'd empty Fultons & start parting them or something!

I have checked the headspace, bolts, boltheads and the receivers after every 150 rounds. Nothing abnormal, no cracks,and headspace still within specs of a NoGo gauge. The rear locking lug setup of these rifles do exactly what they are intended to do,period...

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.

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

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

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. 

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

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.  

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.

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. 

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.

Randy

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...

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. 

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  

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. 

My mistake, I was thinking of the Ishapore 7.62.  Did Pakistan make No. 4 7.62 rifles? 

I would think the Pakistani No. 4 would have the same strength as the British and North American rifles had, if they were made from the same materials and same heat treatment. But, as in all metal structures, there are small variations in strength properties. 

https://calculator.academy/cup-to-psi-calculator/" rel="nofollow - https://calculator.academy/cup-to-psi-calculator/

Wonder if anyone actually knows what the #4 actions were Proofed to?

"Strong Enough,"  is not an answer? It is more of a Question?

Randy

But, the "tons per square inch" units of pressure measurement does not correlate to CUP or PSI standards used in the US and Europe, but refers to the unique British system of measuring chamber pressure (axial copper crusher method).  Somewhere on this forum is a post I wrote that describes it; extracted from a NRA American Rifleman magazine article in the 1960's.   The British system of Axial Pressure measurement typically gives a lower value than CUP (at the same actual peak pressure); IIRR, in the range of 80 to 90% of CUP.

A dry proof round was used to proof the barrel, and an oiled proof round was used to proof each action.  

The 18.5 TSI markings on the LE's released from service refer to the typical pressure of the MK 7 service cartridge, not the proof pressure.  If you convert that to a pressure measurement in lbs/in^2 gives 41,440 psi (2240 lbs in a British long ton); which you can see, is less than the usually accepted 45,000 CUP (US system of radial copper crusher method) as a safe maximum load for use.