Question about case life with the #4 in 7.62 NATO?

[ireload2]

Anyone have any reloading experience with one of the #4Mk1s that were rebarrelled to 7.62 NATO. I was wondering what case life is like with that conversion.

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Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Edward Horton]

Moderators

Ireload2 is reopening a subject that was already locked down here, he is doing the exact same thing he was doing at Gunboards and is just looking for an argument and to create trouble.

Inherent Weakness ? - Military Surplus Collectors Forums

Are the moderators at this website going to allow the same repeat performance by ireload2 and Alfred that happened at Gunboards to happen here also?

The last four threads I started at Gunboards were locked down because of ireload2 and Alfred arguing and it is starting all over again here.

[villiers]

Under different circumstances, I´d have taken this question seriously.

[Alfred]

Under different circumstances, I´d have taken this question seriously.

Its a simple enough question.

The 7.62 NATO cases are much thicker walled than most .308 cases, so as long as loads are worked up at reasonable pressure levels the cases should last a long time.

Low end 150 grain bulleted loadings of the .308 generate only a few percent more chamber pressure than high end .303 loadings, and there are many .308 handloads that generate pressures equal to the .303 MkVII or even less.

The Winchester semi balloon head match cases were introduced to allow use of the heaviest bullets while maintaining enough powder space to avoid excessive pressures. The same loads considered safe in the larger capacity case loaded in a thick walled 7.62 NATO case could be dangerous in any rifle.

I haven't seen any mention of the headspace specs for the L42 in the articles on this rifle found on this site. As a long range sniper rifle I'd expect it would have tighter headspace than a battle rifle. If so that should allow long case life with loads that don't overly stress the action.

[No4Mk1(T)]

This could be a legitimate question or an attempt to do an end run around a locked thread. (Yes I know what it actually is but I’m offering a second chance here) I will allow this to go forward for now BUT if this thread takes the same course as the last I will be locking it and issuing Infraction Points.
Have a read here BEFORE you post below me:

What is the Infractions system? - Military Surplus Collectors Forums

This is the only warning this time.

[jmoore]

L42's have cases with 3 reloads so far (150 gr 2800 fps matching British ball vel.) Lots of cases so not many cycles.

[Edward Horton]

The .303 British is rated at 45,000 CUP or 49,000 PSI
The 7.62 NATO is rated at 50,000 CUP or 60,000 PSI ( The 118 sniper round is rated at 52,000 CUP which makes the 308 and 7.62 equal in pressure)
The .308 Win is rated at 52,000 CUP or 62,000 PSI

Alfred is incorrect about .303 pressures being close to each other, there is 5,000 to 7,000 CUP difference and 11,000 to 13,000 PSI difference between the .303 and .308/7.62.



The No.4 Enfield is made to withstand the pressures generated by the .308/7.62 in military configuration or civilian form as the Enforcer.

Please read “The truth about the 7.62x51mm NATO and .308 Winchester” in the link below, I was contacted by the author in 2008 thanking me for my efforts in helping fighting the myth about the .308 and 7.62 being different cartridges (read the sixth posting from the top by FALPhil)

I hope this puts the ignorance and lack of knowledge to rest about the .308/7.62 and urban myths, the .308 and 7.62 are one in the same here in the U.S. and by CIP in Europe.

Please click on the link below.

Please Critique This Article: 308 Win vs 7.62 NATO - TheFiringLine Forums

[Alfred]

L42's have cases with 3 reloads so far (150 gr 2800 fps matching British ball vel.) Lots of cases so not many cycles.

Can you give us the estimated chamber pressure for these loads?

Found this on the Sierra site

Civilian offspring of
NATO’s 7.62 x 51mm
service cartridge, the
243 Winchester, the
wildcat 6.5mm-08, 7mm-
08, 308 Winchester and
the 358 Winchester.

They also list these bullets for the .308

#2165 .308" 200 gr. SBT
C.O.A.L. 2.800"
#2230 .308" 200 gr. HPBT
MatchKing
C.O.A.L. 2.800"

So they list the .308 as one of the "offspring" of the 7.62X51, not as the same cartridge, and produce bullets for the .308 that are far heavier than those used for 7.62X51 Ball ammunition for use in infantry rifles.

US Bolt action Sniper Rifles of today are militarized versions of Civilian .308 rifles, not converted WW2 rifles, so they would be proof tested to the same standards as the SAAMI requirements for the .308 rather than the less stringent requirements of the NATO cartridge.

As I said earlier

Low end 150 grain bulleted loadings of the .308 generate only a few percent more chamber pressure than high end .303 loadings, and there are many .308 handloads that generate pressures equal to the .303 MkVII or even less.

Thats "Low End" loadings, you can check the handloading data manuals and find many "low end" .308 loads that generate pressures far below the average pressures of either the top end .308 or 7.62 NATO pressures, just as you can find lower pressure loadings for practically any cartridge.

If the M118 Special Ball generates 62,000 PSI then it would not meet NATO maximum chamber pressure specs for Great Britian. M118 Special Ball would not be aproved for use in 7.62 rifles proof tested according to British regulations.
It may be aproved for use in their most modern Sniper Rifles, but nothing indicates that it is acceptable for use in the L42 or any Converted WW2 era action.

7.62 mm (7.62x51mm NATO) Designed to chamber NATO ammunition 415.0 / (60,190) 519.0 / (75,275) Pressure recorded in NATO design EPVAT Barrel with Kistler 6215 Transducer or by equipment to C.I.P. requirements

The same information is available from the British MOD, pressures there are expressed in "Bar" each Bar=14.5 PSI.

[Alan de Enfield]

Can you give us the estimated chamber pressure for these loads?

Found this on the Sierra site

They also list these bullets for the .308


So they list the .308 as one of the "offspring" of the 7.62X51, not as the same cartridge, and produce bullets for the .308 that are far heavier than those used for 7.62X51 Ball ammunition for use in infantry rifles.

US Bolt action Sniper Rifles of today are militarized versions of Civilian .308 rifles, not converted WW2 rifles, so they would be proof tested to the same standards as the SAAMI requirements for the .308 rather than the less stringent requirements of the NATO cartridge.

As I said earlier

Thats "Low End" loadings, you can check the handloading data manuals and find many "low end" .308 loads that generate pressures far below the average pressures of either the top end .308 or 7.62 NATO pressures, just as you can find lower pressure loadings for practically any cartridge.

If the M118 Special Ball generates 62,000 PSI then it would not meet NATO maximum chamber pressure specs for Great Britian. M118 Special Ball would not be aproved for use in 7.62 rifles proof tested according to British regulations.
It may be aproved for use in their most modern Sniper Rifles, but nothing indicates that it is acceptable for use in the L42 or any Converted WW2 era action.


The same information is available from the British MOD, pressures there are expressed in "Bar" each Bar=14.5 PSI.

To me this looks to be going the same way as several of the other threads by Alfred & Ireload2 - starts with a simple (innocent ?) question and then starts to post all sorts of answers to a question that hasn't been posted.

1) I see this as going towards the same argument 7.62 Vs 308 - the original questions was case life in a No4 7.62

2) What has pressure differences between a 303 and a 7.62 got to do with it ? The original question was case life in a No4 7.62

[Alfred]

This document gives the acceptable Chamber Pressure of a number of US Military 7.62X51 cartridges, some are listed in both CUP and EVPAT PSI measurements.
http://www.everyspec.com/MIL-SPECS/M...T3).008538.PDF

Many of these are listed as generating 48,000 CUP and 51,000 PSI, only the M118 Long Range Special Ball is listed at 52,000 CUP.

51,000 PSI is only 3,000 PSI above the maximum SAAMI pressures for the .303, so its likely catridges loaded to pressures no higher than 51,000 PSI would be safe enough for the L42 rifles that passed proof were marked on the Bolthead with the 19 Ton markings. If the .303 rifles bear an 18.5 Proof Mark then the one half ton marking should translate to the rifle being safe with cartridges loaded to 48,000 CUP (about that of MkVIIIZ MG ammunition) or 51,000 PSI, which is far below the maximum pressures now allowed by the MOD for 7.62 NATO ammunition.

The L42 went out of service around the time that the much hotter M118 Special Ball came into use. Its highly unlikely that the L42 was ever authorized to use ammunition loaded to chamber pressures this high.

Also since the rest of the US Mil Spec ball ammunition suitable for regular combat use in battle rifles is listed at pressures of 48,000 CUP its likely that M118 Long Range Special Ball is not considered suitable for all NATO rifles, and it does not meet EVPAT standards.

Conclusion would be that the L42 is not suited to higher pressure 7.62X51 loadings and not suited to the highest pressure .308 Winchester ammunition.

2) What has pressure differences between a 303 and a 7.62 got to do with it ? The original question was case life in a No4 7.62

The No.4 rifle was designed to handle WW2 era .303 ammunition with a decent margin of safety.
Chamber pressures a rifle was designed to handle safely are very important to handloading for the individual rifle.
A .308 load that is safe enough for a modern Long Range Sniper Rifle that is manufactured to SAAMI standards may not be safe for a converted WW2 era sniper rifle when chamber pressures as high as 62,000 PSI were not envisioned for the 7.62X51 NATO cartridge when that conversion was aproved. The rifle was never proofed for cartridges producing 62,000 PSI and if it were built today it would still not be required to be proofed for use with cartridges of that pressure range by MOD standards.
Pressures of 62,000 PSI would be excessive for the L42, its not proofed for this pressure level and never would be.