FWIW, my first experiences with 855A1 were in 2012 on deployment. I PCSed after that deployment to a new unit, and we shot A1 exclusively there. I never had, nor witnessed, any malfunctions relating to magazines or anything else. Accuracy was good as well.
I think it was a dumb move considering some of the COTS options available, and I think that the services should all consolidate into one proven round, (I'll defer to Doc Roberts), but my personal experience, albeit anecdotal, didn't show any issues with the A1 at least.
It is my opinion that the case I got was a bad lot. How, I don't know, because the ES on the velocity was the lowest I've ever clocked, and the tips didn't "spin" on 90% of the rounds I had, and they looked GOOD. I don't have a machine to balance the projectiles though, so they could have had a lot of "wobble". Some of my groups were 2MOA for 10 shots, and some were terrible. Average was 4.55. Velocity for a 10shot string from a 16.1" CHF DDM4 is as follows. All accuracy and velocity testing I did was used with this gun. It has proven to shoot damn near ANYTHING into 2.5MOA at the very worst, including XM556FBIT3, and any TSX bullet. Gold Dot from this gun hovers around 1 MOA. 10-shot groups, 100 yards, using a 4X Nightforce. For the record, it shoots MK318MOD0SOST into about 2-2.5MOA, across multiple lots of ammo.
*Fired through SF 556-212 Suppressor. I have NOT found this suppressor to alter velocity or SD in any meaningful way with other ammo.
**I found the round to contain 25.7gr of SMP-842 powder.