Part II of "Requirements for replacements of currently issued 5.56 M-855 and 7.62 M-8

[stanc]

Here's a rough draft of a lethality description. I felt guilty about arguing about testing without moving forward.

Yeah, well...I really should have taken my posts about 6.5G testing to a different thread. It's just too eeeeeasy to reply to someone off topic in the same thread. :o

So, I banged this next one out and am putting it on the wire early so folks can through some stones:

Requirement 3: Lethality

Threshold: Bare Gelatin

[INDENT]Penetrate at least 30 cm into bare gelatin conforming to the FBI Test 1 description with the average width of the permanent cavity at least 2. cm over at least 10 cm using a bullet design conforming to the NATO interpretation of Hague and Geneva conventions.[/INDENT]

Rationale: This threshold requirement makes the bullet lethality at least equivalent to the 7.62X51 M80 round in the first 30 cm of penetration.

For equivalent performance, shouldn't the wording be something like "...the average width of the permanent cavity at least 2.0 cm, over a distance of 20-35 cm into the gel block..." ?

Objective 2: Robust wound channel

Penetrate at least 40 cm into bare gelatin with the damage channel being greater than 2.0 cm in maximum dimension within 10 cm of the entry.

Rationale: Specifing the width of the damage channel at 10 cm means that the channel will almost certainly be starting to open at about 5 cm into the gelatin block.

This seems like an unrealistic expectation to me. The fastest yawing FMJBT bullet appears to be the 5.45x39 M74, which has onset of yaw at ~7cm. IIRC one of Fackler's articles, the reason that happens is imbalance caused when the lead plug in front of the steel core flows assymetrically upon impact. Since lead is verboten for the next generation military bullets, it's questionable if yaw can be made to happen at 7cm, let alone 5cm.

Judging by Fackler's wound profile drawings, it looks as if the best that might be achieved -- with FMJ bullets having lightweight material (such as aluminum) in the nose, to shift CG rearward -- is onset of yaw at ~10cm, as with the .303 MkVII round.

FWIW, non-fragmenting FMJ rifle bullets typically penetrate about 60cm into gelatin, so specifying 30-40cm is hardly a challenge.