Case 40mm M118

Thanks to various sites hosting pdf versions of all manner of ordnance manuals, I know the expected muzzle velocity of many rounds.

I know the total weight of the round.

I know the weight of the propellant used.

I don't know the weight of the projectile, and I need that for the GURPS damage calculations.

But if you subtract the weight of the case and the weight of the propellant...  You are left with the weight of the projectile!

I needed to find the weight of the case for a 40x46mm grenade.

I remembered that FuzzyGeff has such a case that he's had for as long as I've known him.  He can tell us how he came to own it if he'd like to comment.

What he could do was weight it!

1.6 oz. or 48g on his scale.

I can now calculate what a 40mm HE round does to its victim inside the arming distance.

0.503 lb. (3,521gr)  total weight.

0.1 lb. (700gr) is the case.  (Can you believe I actually used a calculator to go from oz to lb?)

330mg (5.1gr) is the powder.

That leaves 2,820.993gr (0.403 lb.) for the projectile!  (I'd guessed about 2,800gr earlier!)

250 fps is the muzzle velocity.

1d+2 using Douglas Cole's interior and terminal ballistics spreadsheet.  Just like it was with 2,800gr...  At least I know for certain now!

I decided to go with crushing damage because of the big frontal area and low velocity.  Other rounds get double knockback, so I did that too.  It seemed wrong for it to do pi++.

1d+2 cr dkb.

That will do an average of 5 rolled and 5 inflicted.

For the record a 90mph fast ball is a 73.66mm, 2,242 gr projectile at 132 fps. 

1d-2 cr dkb.

A 90 mph baseball does an average of 1 rolled and 1 inflicted.