I recently purchased an unfired Colt A2 that’s been sitting in a closet for 25 years. Included in the deal was 200rds of UMC 55gr that appears to have been sitting in the same closet all that time. On my first 2 range outings I shot 190rds of the UMC with no problems. I then bought some Privi M855, 150 rounds later and again no problems. Last range outing I still had 10rds of the UMC left. Earlier in the day I shot about 100rds of the Privi, I then loaded a mag with my remaining 10 of UMC and topped off the mag with the privi. The privi shot fine, but as soon as I hit the UMC I was getting fail to fires on each of the remaining 10 rounds. Switched back to privi and everything was fine again. I checked the casings and the privi had deep indentations but all 10 of the UMC’s were light strikes. The rifle had a full cleaning after each range outing.
Can’t say I’m worried about anything just curious for some speculation. The main reason I ask is because I know you’re not supposed to follow steel case with brass, wondering if the same holds true with 55gr vs. M855. I’m a long time AK/M1A shooter and I’m a little pissed with myself that I didn’t think to tap the forward assist but it’s just not part of my muscle reflex yet.
