12 July 2021

Damage Mass Equation

 

Building on our post here, how does a shorter barreled 5.56 gun and a 16" .300 Blackout fare?

Loaded 14.5" M4 with optics and light is 8.4 lb.

Loaded 16" 5.56 M4gery with optics and light is 8.8 lb.

Loaded 16" .300 Blk M4gery with optics is 8.7 lb.

Even though the magazines are the same, .300 Blackout is heavier per round so a loaded mag is 1.2 instead of 1.1 lb.

Basic loads are 15 lb., 15.4 lb., and 15.9 lb. respectively.

You will notice that you take a range penalty with a shorter barrel and 5.56 and that .300 Blackout doesn't reach out as far either.

5.56x45mm from a 14.5" or 16" barrel will do 4d+2 pi doing 1,260 to 5,460 points of damage with an average of 3,360.  That gives 224 points per pound for the 14.5" and 218.2 points per pound for the 16".

.300 Blackout will do 1,260 to 6,510 points of damage with an average of 3,885 for 244.3 points per pound on average.

Summing up, per pound from best to worst...

16" .300 Blackout = 244.3 but you slam into 1/2D range 250 yards sooner than even a 14.5" 5.56 gun.

16" 6.8x43mm = 224.2

14.5" 5.56x45mm = 224

16" 5.56x45mm = 218.2

20" 5.56x45mm = 212.4

But this is a bit unfair...  The heavy ARs have fixed rifle stocks, and that's 0.3 lb. heavier right there.

That'd drop the damage per pound of the .300 to 239.8.

Putting a carbine lower on the 6.8 would increase it to 228.1.

The configuration matters and this ends up being an oranges to grapefruit comparison.  You can shave mass from any of these guns to the tune of half a pound just changing furniture.  Magpul stuff is heavy compared to USGI.  KAC's RAS is very heavy.

For example an M16A1 and aluminum USGI 30-rounders is 7.8 for the rifle and 14.8 for the basic load.  Damage is 1,050 to 6,300 with an average of 3,675 for 248.3 points per pound.  But no optics and range of just 500/3,200.

Just in case you're curious...

A 6.5 Grendel M4gery does 6d-1 pi out to 730/4,000.  Weight is 7.5/1.3 with 24 round PRI magazines.  Add 1.4 for a 5x prism and X300 for 8.9 lb. for the gun and 16.7 lb. for the loaded gun and 6 spare mags.

168 rounds down range will do 840 to 5,880 points of damage with an average of 3,360 which gives 201.2 per pound.  GURPS doesn't like Bill Alexander's furry nation either.

1 comment:

  1. I like .300 Blackout, but I don't actually intend to rely on it for home defense. It is however, currently at the top of my list for hogs. I don't plan to take shots beyond 75 yards for them, so the range doesn't matter. I don't have a 6.8, or it would be considered. I'm not comfortable using 5.56 for hogs. It would probably work, but the fat and heavy .308" bullet gives more margin for error. Actually I'm kind of torn about using my M1A or my MAS 49/56... No question .308 Win (commercial hunting loads) or 7.5x54 French MAS will git-r-done. But the M1A is long and heavy and the MAS 49/56 has no good scope options at the moment. I've got numerous bolt action options, but hogs are often found in large groups and there is no bag limit... sooo... Anyway the latter options would make more sense if I planned on long shots, but the terrain where I would be likely to find myself is too hilly and full of scrub brush and trees like Mesquite and Juniper Cedar to allow for visibility past 50-75 yards.

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