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Posted: 4/6/2009 6:37:58 PM EDT
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what is the "rated" penetrating power of a M855 round versus per say a steel plate? i got a small handful of M855 and i was testing it up against a 1/4 inch steel plate just for shits and giggles and they punched right thru it like nothing. my first thought was "sweeeet; AP goodness", but than i shot the same plate with a reg. PMC 55gr. FMJ (for comparison to the M855) and it too punched right thru it with ease. .....? ....? im a little confused. ive read in a few places that 1/4 inch steel was the max. a M855 can penetrate.. and yet average joe FMJ rounds punched thru it too, and actually made a cleaner hole and the point of exit was larger than the M855. i was shooting it from 50 yards. the FMJ even had enough power left after it went thru the plate to go thru one side of a cinder block afterward.
any insight would be amazing. as since i am clueless about what to make of this my bud suggests i should try 3/8" plate. i have no idea of the grade and/or hardness of the steel i was shooting. it was really heavy and seemed like a average steel plate... |
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Might want to read the Ammo forum FAQ at the top of the page. This part kind of addresses your question. http://ammo.ar15.com/ammo/project/term_m855pen.html
M855 isn't, and isn't supposed to be, armor piercing. M193's higher velocity allows it to actually penetrate better at shorter ranges. |
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Two problems with your research.
1. You might not know what the hardness of you plates are. M855 won't penetrate 1/4" AR500 plate. So thickness means nothing if you don't know what you're shooting. 2. M855 doesn't penetrate steel better than M193 for shit. I did research on this a while back and the photos were posted here. M855 does not penetrate hardened steel for shit. And M193 actually does MORE damage to hardened steel due to the higher velocity of the projectile. Though neither penetrate anyway so it's irrelevant. The point is the M855 doesn't improve penetration on steel. The bottom line is that M855 doesn't do much of anything very well. What you get when you buy first line M855 is high quality control ammo. |
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I tested M855 a lot at one point. It would go through 3/8 plate steel w/more retained penetration ability than any other round in 5.56 I tested. I have yet to load up some 45gr solid brass monolithics though.
At 150m It would penetrate the 3/8" steel and then through 1.5 2x4's. M193 would not penetrate as well at any range, only knock a scab off the back of the steel plate that would form a nasty dent in the 2x4. No matter how close I got (within reason, I stopped at 25m to not get caught in back-splash) |
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Quoted:
The M855 round was designed to penetrate a steel helment at 500 yards. It will not penetrate kevelar at that range. Quoted:
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A kevlar helmet at 500m IIRC. I thought it was the old M1 steel helmet that was used as the test standard I stand corrected. I knew I was off on at least one dimension. |
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Quoted:
Depends on the type of Steel 
Very true. It ALSO depends on the range. M193 loses velocity FASTER than M855. So there's a window (outside of most civilian engagement ranges) where M855 should penetrate better on hard targets. I've read some accounts where guys have actually had M855 penetrate better on certain steels at certain ranges. For the most part though, M193 is the superior choice for general purpose ammo in the civilian or even L.E. realm. |
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Quoted:
Two problems with your research. 1. You might not know what the hardness of you plates are. M855 won't penetrate 1/4" AR500 plate. So thickness means nothing if you don't know what you're shooting. 2. M855 doesn't penetrate steel better than M193 for shit. I did research on this a while back and the photos were posted here. M855 does not penetrate hardened steel for shit. And M193 actually does MORE damage to hardened steel due to the higher velocity of the projectile. Though neither penetrate anyway so it's irrelevant. The point is the M855 doesn't improve penetration on steel. The bottom line is that M855 doesn't do much of anything very well. What you get when you buy first line M855 is high quality control ammo.  Well say!!! thanks for your explaininations!
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