Quote:
Originally Posted by CDAT
I guess that I was not clear in what I was trying to say, I was more commenting on how you are the only one that I know of that talks about how a 5.56mm has better penetration than a 7.62mm. Also having looked a bit more into it SAPI plates are not rated by NIJ they are rated by ARMY MIL-STD-662F and STANAG 2920 Ed2, so have different standards (like where you pointed out that they are rated to stop with the vest, are not stand alone). As for the rifle used it was a semi-auto AR with 20 inch barrel, we used green tip, black tip, Mk 262 (I am guessing that is what you are talking about when you said Mk 282?) and a bunch of civilian rounds, we did not use the M855A1 I have heard great things about it, but no first hand experience. Some shots as close as 50ft, an never had a single round penetrate, however they were not SAPI plates, they were level III plates. I have not had the time to watch the videos, but going back over my notes from the training I did have a note how the Polyethylene Plates could have penetrations at some velocities, we did not shoot them we only shot the Ceramic and Steel Plates.
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It has only recently been shown that plates can be penetrated by certain rounds and ALL of those rounds have a similar set of traits. Those traits are a Sectional Density of 0.15 to 2, a small diameter caliber (think about the 5.7 as well here) and a Velocity ABOVE 3000fps for Level 3/SAPI. Velocity it seems is the key to ARMOR PENETRATION (but not necessarily "barrier penetration"). Not just 5.56mmN but several rounds exceeding 3000fps have been found to penetrate armor plates. In soft armor, 1800fps seems to be the "threshold" to penetrate NIJ Level 3A soft armor (check out Tim at The Military Arms Channel's tests on Levels 2 and 3A soft armors) and 1400fps appears to be the "threshold" for penetrating NIJ Level 2 soft armor (check out the tests Tim does with 7.62mm X 25mm T military ball). This is why I'm "espousing" velocity as the primary measure for PEN (the stat) in Twilight2000. Keep in mind that while a 5.56mmN 55grain M193 will penetrate a Level 3 plate at close range (turning the BATF's AP argument against M855 completely on its head); But, once its velocity drops below 3000fps, it will NOT penetrate the plate (which can happen as close as 40 meters out). This is why I figure PEN (the stat) for EACH Range Band based on a round's velocity for that range band (I use the range at the middle of said range band for this). This not only adds variety to the game but also provides certain limitations on some weapons. For instance, just because the 20" barreled M16A2 can penetrate NIJ Level 3 at Short Range doesn't mean that the 14.5" barreled M4 can. It gives a player a choice to make, the lighter, handier, M4 or more effective (with regards to range and PEN) M16A2.
The 7.62mmN will NOT have the PEN (the stat) that 5.56mmN has but DON'T look at 7.62 through the narrow lens of just the PEN stat. In my game, it has 4D10 Damage dice (at Short range) to 5.56mmN's 2D10 Damage. You have to look at DAM and PEN as a unit to really determine what a given round can penetrate. This is why I use a round's Energy to determine the DAM it can do (as per FF&S/Small Arms Guide formulas). I do this by Range Band too. The 5.56mmN may look impressive because it MAY (depending on barrel length) penetrate a Level 3 plate at short range, but look further out in Range Bands and you will see WHY 7.62mm is still used in MGs and Sniper Rifles (5.56mm begins to lose its "shine" starting at Medium Range). My point here is DO NOT look at PEN ALONE, you must assess PEN & DAM TOGETHER for an accurate view of what a round can do.
Thanks for catching that Typo on MK 262. I was talking about the Black Hills 77grn Open-Tipped Match round. The only 5.56mm N round in my game to make the 3D10 threshold (I modified the DAM calculation slightly by rounding up or down in various steps). It won't penetrate a Level 3 plate either (its lowered velocity nets it a PEN of 2).
Quote:
Originally Posted by CDAT
No, I did not see you mistake, as I was also told in my class it was one round for level four plates. This was just more a comment on how tough some of the vests are from actually shooting them not reading reports or watching videos but first hand doing. Kind of saying how just because something is rated for X that does not mean it can not do more, you may not want to count on it to do more but sometimes it can.
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I couldn't agree more. I have sacrificed 2 helmets, 2 soft vests, and a hard trauma plate (NIJ Level 3) to "see for myself" just how effective armor is.