PMAG-25 LR/SR W (Black)

 For gaming purposes, I obtained a Magpul MAG292-BLK PMAG-25 LR/SR W.

That's a 25 round magazine for your "AR-10" with the SR-25 or DPMS magazine well.  The standard magwell now that the AWB is dead.

It sticks out a bit more than the 20 rounder.

The extra five rounds comes with a weight penalty; 1 lb. 12 oz. loaded compared to 1 lb. 6.8 oz. of the PMAG-20 LR/SR.  1.8 lb. vs 1.4 lb. in GURPS terms.  That changes the weight of the M1956A2, pictured above, from 11.7 lb. to 12.1 lb. as shown.  That also changes a load of 6 spare magazines from 8.4 lb. to 10.8 lb.  The more traditional 4 spares for a battle rifle goes from 5.6 to 7.2 lb.  You do go from 120 spare rounds to 150 (or 80 to 100 with the traditional loadout).

The cute little window is rendered a little useless by not including any numbers, but you can still check to see if there's any ammo in there with it.

Magpul no longer includes a dust cover.  C'est la guerre.