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Best surplus ammo for nato 7.62x51 Enfield Pt 2

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Goosic View Drop Down
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    Posted: April 07 2020 at 1:23pm
To the Original Poster of this. You had asked a question about the best surplus ammunition for,what I am to assume is an Ishapore 2A1 rifle chambered for the 7.62×51mm NATO cartridge?  I understand your worry about using normal 308 Winchester ammunition.  Let me help alleviate some issues you may have. The Ishapore 2A1 was not made using recycled No1Mk111 receivers.  They were made with all new steel at the time and were proofed to 19 tons of pressure, unlike the normal 18.5 tons of the 303 cartridge. That being said. The 303 has a maximum Copper Units of Pressure(CUP) of 45,000 whereas the NATO cartridge has a maximum (CUP) of 62,000 but rarely meets the maximum unless it is used in Long Range shooting competitions/benches by handloaders. The average LR military cartridge  used by the U.S. is a 175grn Sierra MK .308,primed with CCI #34 NATO spec magnum primers and loaded with 41.7grns of IMR4064 powder all packed inside Federal Cartridge cases. It has a CUP of a mere 46,800. Federal commercial ammunition  offers the .308 Winchester in 150 grain that typically do not exceed 42,100 CUP. Their 180grn does not exceed 44,700 CUP.  Both functionally safe to use in your Ishapore.  I have a No4Mk2 that I converted to 7.62x51mm as well as a No5Mk1. Both rifles have had commercial, military, and handloads through them and to date have had no issues.  Take from this what you will. Commercially loaded 308 ammunition is not loaded to any maximum pressures and will not act adversely in a military chamber.
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britrifles View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: April 07 2020 at 2:23pm
The .308 Winchester commercial spec ammo will not exceed SAAMI specs for that cartridge. 

 So, anything up to 62,000 psi Maximum Average Pressure (Piezo Pressure method), or 52,000 CUP Maximum Average Pressure (copper crusher method).   I would not be comfortable shooting .308 commercial ammunition in my No. 4 7.62 NATO conversion unless I knew the MAP for that specific load.  And, it may be subject to change.  

I don’t particularly like shooting 7.62 NATO ball ammunition either, although I’m probably erring on the side of caution here, I want to minimize wear on the action.  I prefer handloading to .303 velocities for the same bullet weight.  




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Post Options Post Options   Thanks (0) Thanks(0)   Quote Goosic Quote  Post ReplyReply Direct Link To This Post Posted: April 07 2020 at 3:14pm
Lyman has a perfect handload for .308/7.62×51 that gives you a 35,500 Copper Units of Pressure, per the Lyman reloading manual using exactly 40.0grns of IMR 4064 with a 168grn BTHP and primed with Remington 9 1/2 primers.  That is almost 10,000 CUP under the 303B of 45,000 CUP
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: April 07 2020 at 3:45pm
That’s one of the advantages of handloads.  Total control of pressure and velocity.  

I use 40.0 grains of Varget in both .303 and 7.62 reloads using a 174 gr and 168 gr boat tailed bullet respectively.  Both loads are well under the SAAMI maximum MAP for .303 and very accurate.  40.0 gr of IMR 4064 would be very similar.  










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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: April 07 2020 at 7:21pm
how come the OP is not here anymore ? 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shamu Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 6:46am
Not a clue, sorry. Usually if the OP in a thread is deleted the whole chain goes away?
Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote The Armourer Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 9:00am
Originally posted by Goosic Goosic wrote:

I understand your worry about using normal 308 Winchester ammunition.  Let me help alleviate some issues you may have. The Ishapore 2A1 was not made using recycled No1Mk111 receivers.  They were made with all new steel at the time and were proofed to 19 tons of pressure, unlike the normal 18.5 tons of the 303 cartridge. .


It is important to remember that SOME of the "A2's WERE manufactured using scrubbed re-cycled 303 bodies.

The 303 bodies were manufactured in an EN steel, which, believing it would offer better performance Ishapore changed the steel for the 7.62 to a 'better' SWES steel.
On proof testing the bodies twisted and the bolts jammed with both the 'oiled round' and 'dry round' tests.

Ishapore then reverted back to the EN (original) steel which when proof tested with the standard (at the time) 144 grain 7.62 it still failed the 'oiled round' test, but did pass the 'dry-round' test.

Even tho' the specification called for both oiled and dry round testing every subsequent rifle was only proofed using the dry round test.

Source :

"Gun Proof in India - An Historical Account." It was written by Mr. A. G. Harrison the former Proof Master at the Rifle Factory Proof House, Ishapore, India and was published in "The Gun Digest, 33rd Edition, 1979."

It is important to remember that bullet weight is important, and that the rifle was built to fire 144g bullets, so only 144g - 150g bullets should be used.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Goosic Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 10:08am
You forgot to mention that they exceeded 20 plus tonnes of pressure to get the receivers to twist...
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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: April 08 2020 at 10:13am
interesting information , valuable to those that load for and shoot these old rifles [interesting i think of them as old and they are actually some of the newer made] ive always thought of the shotguns as being the less dangerous with no good logic behind the thought other than shotgun pressures ,
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Goosic Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 10:24am
...as a sidenote,and this is just for the IMR4064 powder only. When used in the 7.62x51mm NATO cartridge in conjunction with bullets from 125grn through to the 200grn bullet and loading to just the suggested starting grain, you never exceed the PSI reading of 47,000 which is 3000 PSI below that of the 50262 PSI of the 303B.
The equation is supplied in another thread of mine fyi...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 2:50pm
It never made much sense to me that bullet were limited to a specific weight in a given rifle.   People have sworn that the gas system (Op rod) can be damaged in the M1 if you load anything above 150 gr bullets.  But they forget the M1 when approved for the US military the M1 .30-06 cartridge which used a 173 gr bullet was in use at the time, the M2 cartridge had not been developed yet. 

I can’t see how shooting 168 or 175 gr bullets, if properly loaded to not exceed published data, could damage the rifle.  But as I’ve said, I personally stay well below the published maximums for .308 in my No. 4 conversion.  It shoots the 168 gr SMK very well out to 600 yards.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Goosic Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 3:10pm
The convertion  from PSI to CUP is PSI x 1.21 - 15817 =CUP
168grn .308 BTHP
40.0 IMR4064 has a PSI of 36882 and converts to a CUP of 28737.62
41.0 Varget  has a PSI of 42200 and converts to a CUP of 35425

174grn .311 BTHP 
40.0 IMR4064 has a PSI of 38700 and converts to a CUP of 31010
40.0 Varget has a PSI of 43900 and converts to a CUP of 37302

The interesting point here is that the published data has the .308 operating well below that of the 303 British 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WilliamS Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 3:12pm
Originally posted by britrifles britrifles wrote:

It never made much sense to me that bullet were limited to a specific weight in a given rifle.   People have sworn that the gas system (Op rod) can be damaged in the M1 if you load anything above 150 gr bullets.  But they forget the M1 when approved for the US military the M1 .30-06 cartridge which used a 173 gr bullet was in use at the time, the M2 cartridge had not been developed yet. 

I can’t see how shooting 168 or 175 gr bullets, if properly loaded to not exceed published data, could damage the rifle.  But as I’ve said, I personally stay well below the published maximums for .308 in my No. 4 conversion.  It shoots the 168 gr SMK very well out to 600 yards.  

Personally I think bullet weight matters more for matching trajectory to the sights in milsurps than it does for safety.  For semiautomatic rifle function I think the pressure curve is more important (bullet weight plays a part but only a part).  Of course, when the M1 was adopted with M1 ball, it was with the gas trap system.  I think M2 ball (M1906 spec) was adopted before the change in gas systems, so I wouldn't be surprised if M1 ball in any non gas trap rifle could potentially have the wrong pressure curve.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Shamu Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 3:23pm
Unfortunately those are approximate calculated conversions. Useful for "checking it out" but not really accurate over the entire range.
On of the biggest things in reloading is CUP, Vs PSI.
the two do not change the same way over a range.
Don't shoot till you see the whites of their thighs. (Unofficial motto of the Royal Air Force)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote britrifles Quote  Post ReplyReply Direct Link To This Post Posted: April 08 2020 at 3:45pm
Both gas trap and gas port systems were in service when the M2 ball was developed, so it had to work in both.   Although, most of the Pre-1939 gas port M1s ended up being modified to the gas port configuration.   They were more concerned about exceeding the range safety zones with the M1 ball, so went to the lighter flat based M2 bullet to limit range.  I don’t think it had anything to do with concerns that the 173 grain bullet was damaging the Op Rod. 

I don’t recall if the elevation marks on the range drum were changed when M2 ball was introduced, out to 1200 yards, the trajectories are very close out to 800 yards.  

My only other comment in handloading is to be cautious when attempting to do light loads.  Some powders do not behave well with air space.  Not usually a problem in loading .308 to .303 pressures and velocities.  But with .30-06, where there is a lot of airspace with modern smokeless powders, this can be dangerous.  





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Post Options Post Options   Thanks (0) Thanks(0)   Quote The Armourer Quote  Post ReplyReply Direct Link To This Post Posted: April 09 2020 at 11:09am
Originally posted by Goosic Goosic wrote:

You forgot to mention that they exceeded 20 plus tonnes of pressure to get the receivers to twist...


They used the standard proof round for 7.62 NATO.

But as a comparison the 308 SAAMI proof round is 35+ tonnes.





Interesting that 308 has higher pressures than 7.62 NATO

Comparisons :


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