Lids

I did a post about the US' issue helmets back here.

I mentioned that the M1 steel pot had different liners and that those liners gave improved performance.

I was unaware that a kevlar liner had been produced in the early '80's pretty much as the PASGT kevlar helmet started issue.

I've made some changes to the GURPS stats since those posts, there's more public domain information on the PASGT for one...

The steel part of the M1 is DR 3.  It weighs 2.6 lb. and would ride far too low on the head for use or comfort.

The liner includes a suspension system that keeps the helmet positioned correctly on the head and a chin-strap.  Try as I might, I can't find a confirmed report of the strap causing decapitation.

The 1941 fiberglass liner gets DR 1, 0.3 lb.  DR 4 and 2.9  lb. total.
The 1965 ballistic nylon liner gets DR 2, 0.8 lb.  DR 5 and 3.4 lb. total.
The 1983 kevlar liner gets DR 4.  <-- this is speculation, I've no hard data, not even weight.  It stands to reason that it will either be lighter than the '65 model for the same protection or more protection for the same weight.  DR 7 and 3.4 lb. total (for now).

Wikipedia gave me the weights for the 1941 model.
GURPS: SEALs in Vietnam gives the weights of the 1965 model.

GURPS Basic Set gives the kevlar DR 5.

I've read reports that says that this is way too low, even if the desired specifications called for it to be about this level.

For my Twilight: 2000 conversion, I gave it DR 10 and 3.6 lb.  The improved version from 1993 scored DR 12 and 3.4 lb.

It gets frustrating because the ACH is supposed to be much better than the PASGT, but it's DR 12, 3.3 lb.  I think that when this was set in the Basic Set they didn't have much information about it, and 12 is significantly better than 5 for protection, but isn't much better than the 10 I think the PASGT rates.

The ACH is NIJ rated as IIIA.  That stops .44 Magnum.  The specified test round is a 240gr semi-jacketed hollow-point at 1,400 fps.  That is GURPS 4d(0.5) pi++.  Average raw damage is 14, max 24.

Because DR is doubled against hollow points, average drops to 7 and max to 12 effectively.

DR 12 is correct for the ACH!  Who knew?  It is lighter and more comfortable than the PASGT, even if offering no more ballistic protection for GURPS.