Moar Weight Less Dakka

To quote from Wikipedia:

The proposed combat ammunition load for each soldier will be 140 total rounds, distributed across seven 20-round magazines, in total weighing 9.8 lb (4.4 kg). Compared to the M4A1 carbine weighing 6.34 lb (2.88 kg) unsuppressed, with a basic combat load of 210 rounds in seven 30-round magazines, in total weighing 7.4 lb (3.4 kg), the XM7 rifle weighs about 2 lb (0.91 kg) more and each soldier carries roughly a 4 lb (1.8 kg) heavier load with 70 fewer rounds.

We can GURPS the damage too!

The M4A1 does 4d+2 pi damage with M855 ammo.  M855A1 does 4d+2 pi+.

I'm showing M855 because there's a debate about M855A1 not really performing any better...

Per round is 6-26 for M855 and 9-39 for M855A1, averaging 16 and 24 respectively.

Basic load for an M4 is 210 rounds.  Average damage per basic load is 3,360 for M855 and 5,040 for M855A1.

6.8x51mm M1186 should be doing 7d+2 pi.  They're quoting 3,000 fps for the carbine, but I think it should be 2,850 with the short barrel.  3,000 is what the SAW has.  Drop damage to 7d pi if so.

Per round is 9-44 with an average of 26 (26.5 actually).  7-42 and 24.5 if lower velocity.

Basic load for an M7 will be 140 rounds.  Average damage per basic load is 3,710.  3,430 with the lower velocity.  That's not a huge improvement considering the extra weight.

It does get a bit more range, and the optic should mean the troops can take advantage of it.

The rub is...  4 extra pounds is 4 30 round magazines for an M4.  That adds 1,920 points of damage, on average, for a load of M855 and 2,880 for M855A1.

With the proposed loadouts:

3,360 M855 < 3,430 < 3,710 M1186 < 5,040 M855A1

Matching the weight of the new proposal.

3,430 < 3,710 M1186 < 5,280 M855 < 7,920 M855A1

Again, I ask, "What four pounds of gear the soldier is currently carrying will be discarded to carry this new weapon and ammo?"

It's an obvious question because we're at our limit of how much they can carry now.

Update:  It's entirely possible that the M1186 will have a composite structure that's a bit like the M855A1.  That would change to pi+ in GURPS terms; so 7d pi+

3,360 M855 < 5,040 M855A1 < 5,145 M1186  Still not a massive improvement overall.