Terminal ballistics-wise: Mk318 or M855A1?

**ABNAK** · 05-01-19, 18:35

In keeping with the theme of this forum, I ask that question. When it hits a two-legged critter, which performs better and more consistently? Let's say for a military force, not Joe Civvie.

Sure, M855A1 has some pressure issues which could make one default to Mk318, but if by some miracle increased wear on the weapon wasn't an issue, which one? Not talking barrier penetration, but I guess that should be included in the discussion.

**vicious_cb** · 05-01-19, 18:44

Originally Posted by ABNAK

In keeping with the theme of this forum, I ask that question. When it hits a two-legged critter, which performs better and more consistently? Let's say for a military force, not Joe Civvie.

Sure, M855A1 has some pressure issues which could make one default to Mk318, but if by some miracle increased wear on the weapon wasn't an issue, which one? Not talking barrier penetration, but I guess that should be included in the discussion.

1st of all M855A1 doesnt have increased wear anymore since they dropped the pressures. Both anecdotally and looking at ballistics gel, M855A1 seems to be the superior bullet. They are very close in performance but when the distances increase and velocity falls off, M855A1 looks to have a lower velocity threshold for fragmentation.

**Wake27** · 05-01-19, 19:26

Originally Posted by vicious_cb

1st of all M855A1 doesnt have increased wear anymore since they dropped the pressures. Both anecdotally and looking at ballistics gel, M855A1 seems to be the superior bullet. They are very close in performance but when the distances increase and velocity falls off, M855A1 looks to have a lower velocity threshold for fragmentation.

I didn’t know that they did drop the pressure. I assume 855A1 is better at penetrating armor, I know it performed well there but I don’t know about 318 in that regard.

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**WS6** · 05-01-19, 19:50

A1 is running functionally the same as legacy 855 pressure wise.
A1 has a lower threshold of fragmentation
A1 penetrates hard homogeneous targets much better
I have personally found mk318 to be much more accurate. YMMV by lot number and barrel.

**ABNAK** · 05-02-19, 05:07

Originally Posted by WS6

A1 is running functionally the same as legacy 855 pressure wise.
A1 has a lower threshold of fragmentation
A1 penetrates hard homogeneous targets much better
I have personally found mk318 to be much more accurate. YMMV by lot number and barrel.

Any idea when this pressure reduction from the original loading took place? I have heard about it but never saw something specific like "After 20XX M855A1 underwent a change where the pressure was decreased slightly".

**WS6** · 05-02-19, 17:58

Originally Posted by ABNAK

Any idea when this pressure reduction from the original loading took place? I have heard about it but never saw something specific like "After 20XX M855A1 underwent a change where the pressure was decreased slightly".

M855A1 was getting tweaked so often it's hard to say, but at least 2 years ago.

**davidjinks** · 05-09-19, 22:06

Pressures have been dropped but there are still issues with the M855A1 damaging weapons.

In regards to terminal ballistics, M855A1 is superior to the MK318. Better penetration, and fragmentation.

Originally Posted by vicious_cb

1st of all M855A1 doesnt have increased wear anymore since they dropped the pressures. Both anecdotally and looking at ballistics gel, M855A1 seems to be the superior bullet. They are very close in performance but when the distances increase and velocity falls off, M855A1 looks to have a lower velocity threshold for fragmentation.

**ABNAK** · 05-10-19, 04:40

Originally Posted by davidjinks

Pressures have been dropped but there are still issues with the M855A1 damaging weapons.

In regards to terminal ballistics, M855A1 is superior to the MK318. Better penetration, and fragmentation.

I'm just recalling this off the top of my head but the originals exceeded 60,000 PSI and now they're down to like 56,000, correct? Don't recall where I read it. So less than the original but still higher than NATO specs.

**WS6** · 05-10-19, 04:41

Originally Posted by ABNAK

I'm just recalling this off the top of my head but the originals exceeded 60,000 PSI and now they're down to like 56,000, correct? Don't recall where I read it. So less than the original but still higher than NATO specs.

They're a few hundred PSI lower than greentip, I believe.