The "Enhanced Performance Magazine"

[lysander]

They fixed the overpressure issue, mostly

Various youtube gel tests have displayed impressive results

The M855A1 has a maximum average chamber pressure of 62,000 psi with a plus three sigma maximum of 66,000 psi.

The pressures generated by M855A1 series ammunition is 3300 psi higher than the M855, 7000 psi higher that the M193, and 12,000 psi higher than the original pressure limit of the cartridge design.

Also, because of the extremely high average pressure and the physical limits of what the rifle locking lugs can take, the standard deviation (sigma) of the ammunition's pressure levels are now 40% tighter than all previous ammunition, tighter than even match ammunition*, making the ammunition even more expensive to produce, beyond the higher cost of the bullet.

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* Note, just because the pressure variation from round to round is held to a tighter standards, it does not automatically follow that the accuracy will be better.

[mack7.62]

Yeah my understanding is there is really no way to get the performance improvements that round was sold on without higher velocity which means higher pressure. Without that it is no better than M855, just a more expensive lead free bullet.

[dpast32]

Morning Guys, I just came across a news item concerning the US Army's latest version of the M4 magazine. Perhaps I've been out of touch lately, but I was under the assumption that the M4 magazine had been updated just a few years ago . In addition to that project, I thought that the Magpul P Mags had also solved some of the feeding issues, what gives ? BTW, the report I refer to was posted via "Kit-Up", & was dated July 2016. THANK YOU

Best, dpast32

[RichFitz]

Guess I never gave it much thought, but do PMags reliably feed M855A1?

The M3 PMag (GEN M3 PMAG BLK NSN: 1005-01-628-5106) has always run the Army's new Enhanced Penetrator Round (M855A1), flawlessly without accelerated damage to the feed ramps of the M4/M16/HK416.

The new USGI uses feeding geometry "strikingly" similar to that introduced with the original PMag M3 8 years ago but it still suffers from reliability and durability issues inherent with the ALU body. Not to mention the PMag offers round remaining feature and has a US Govt cost substantially lower than the new magazine proposed here.

Bullet-Sticker-270.jpg

[Straight Shooter]

As for follower color- somewhere I cant remember, it said they were using BLUE followers.
Don't quote me on this.

[WS6]

I can see where PMAG's mitigate feed-ramp damage, but what about chamber-gouging from the round settling/levering into the chamber? is this or has this been an issue?

[C1-2DG]

The EPM (with blueish followers) is a mess. They have a propensity to fall out of M16A4 magazine wells if loaded above 25 rounds. They also still result in extensive chamber face (forcing cone) damage with M855A1.

The M3 PMags (black, sand, etc) pass all tests to include cold weather drop tests. They have proven to be far and above more reliable and long-lasting than any other mag tested (M4/M4A1, M16A4, and M27) with any ammunition fed.

M855A1 for the Corps is probably happening. While the formulation has changed, chamber pressures dropped to 54,206 PSI and the M4 gas port pressures dropped to 16,709 PSI. Although it has lower terminal effectiveness than the original M855A1 lots, it is a superior bullet to the SS109/M855. So at this point, while Army mismanagement and overspending is through the roof, adopting M855A1 will no longer be a problem - IF it is fed from M3 PMags.

S/F

[WS6]

The EPM (with blueish followers) is a mess. They have a propensity to fall out of M16A4 magazine wells if loaded above 25 rounds. They also still result in extensive chamber face (forcing cone) damage with M855A1.

The M3 PMags (black, sand, etc) pass all tests to include cold weather drop tests. They have proven to be far and above more reliable and long-lasting than any other mag tested (M4/M4A1, M16A4, and M27) with any ammunition fed.

M855A1 for the Corps is probably happening. While the formulation has changed, chamber pressures dropped to 54,206 PSI and the M4 gas port pressures dropped to 16,709 PSI. Although it has lower terminal effectiveness than the original M855A1 lots, it is a superior bullet to the SS109/M855. So at this point, while Army mismanagement and overspending is through the roof, adopting M855A1 will no longer be a problem - IF it is fed from M3 PMags.

S/F

Are you saying current ammo is this lower pressure, or it WILL be lowered?

What about chamber wall damage between the forcing cone opening area and the shoulder, from the tip levering in, mid chamber?

[C1-2DG]

The current ammo is the lowered (54,206 @ neck/16,709 port) figures I posted above.

Between the forcing cone and the shoulder, I personally haven't noted any wear patterns there.

S/F

[Clint]

The current ammo is the lowered (54,206 @ neck/16,709 port) figures I posted above.

Between the forcing cone and the shoulder, I personally haven't noted any wear patterns there.

S/F

For comparison, what are the chamber and port pressures for M193 and M855?