22 WMR v's 22 LR

[Not another shrubbery]

Originally Posted by DouglasCole

The .22WMR at 40gr and 580m/s is 2d+2 pi-. Given soft lead, though, rather than jacketed, it's likely to be worse at armor penetration than usual FMJ type rounds, although less of a spreading bullet than a designed hollow point.

You are a champ, DC! For some reason, I kept coming up with 2d+1 for the .22 WMR, and was convincing myself that that was too high :?

[DouglasCole]

Originally Posted by Not another shrubbery

You are a champ, DC! For some reason, I kept coming up with 2d+1 for the .22 WMR, and was convincing myself that that was too high :?

I'll note that in certain regimes, notably small caliber bullets of poor structural integrity moving VERY fast (5.56x45mm, I'm looking at you!) my system tends to overestimate the penetration by a point. For the M193 round (55gr 5.56x45mm at 990m/s) I get 5d+1; for the M855 (62gr at 945m/s) I get 5d+2. I KNOW the 55gr round is defeated by a 1/4" steel plate about 50% of the time, making the real-world penetration 5d exactly. Not sure about the 62gr green-tip.

So it's possible that I'm overstating the penetration of the .22WMR by a point, and that it IS 2d+1. But I think it's likely that the relatively high energy of this bullet puts it more or less where I left it. Note that the 5.7x28mm round is a bit lower because of the light bullet (31gr) and what seems to be a low-power ammo, relatively speaking. The alternate ammo to which I linked (2d+3 pi, maybe, with a 45gr bullet) would definitely be the "Adventurer's Choice," and if I were issued P90s and Five-seveN's as weapons, would likely be the real-world choice as well.