[currancchs]

243winxb:
Thank you for the link, but it is inoperative for me...


Jimro:
First off, thank you for your detailed response. I'm currently in the process of moving, so it might be a while until I get a chance to section the case (tools are packed), but I will do as you suggest and section a case as soon as I am able and upload pictures when available.

Regarding the XM80, I know from the headstamp that it was LC brass, had no idea about the powder/temperature sensitivity, but will keep that in mind in the future.

On the occasions that I've had the rifle out, its been very hot, mid-90's or so (Southern NH). The XM80 and other brass ammo was shot from a wide open field with no shade on sunny days, the steel ammo was shot on similarly hot days, the first time in direct sunlight, the second time from a covered range.

The XM80 was probably left out for ~20 minutes prior to shooting, in the box, but in pretty direct sunlight... In the future I will be looking for shade, at least for the ammo.

At the time the rifle was piercing the XM80 primers, I was loading it with between 2-5 rounds at a time (working on gas block adjustment for proper cycling) and taking my time between shots. I only shot about 12-15 shots total that day, as the two pierced primers caused me concern and I wanted to inspect the rifle prior to continuing use.

On a further range outing, where I was shooting from a covered/shaded location, but in equally hot weather, I shot ~70 rounds of mixed Federal Gold Medal Match 175gr. SMK and Perfecta 147gr. ammo without any failures, again loading about 5 shots at a time with maybe 15 seconds between shots, taking my time to reload magazines and check targets, probably took a bit over an hour to shoot the 60 rounds.

My last two outings, using the steel cased ammo were on equally hot days (why has it been so hot lately???). On the first outing I was shooting in direct sunlight in an open field with the ammo also in direct sunlight, but only for ~10-15 minutes. I only shot about 15 rounds that day before getting a round stuck in the chamber, which I had to return home to fix as I had not brought a cleaning rod/dowel or hammer... On the second outing, I shot from a covered range and shot ~25 rounds, during which time no malfunctions occurred, until the last round stuck in the chamber, ending my day. The second stuck casing (the one in the original post pictures) came out a bit easier than the first.

Firing pin protrusion is 0.0485'', but take this with a grain of salt;I used a Harbor Freight caliper to measure the protrusion

When I started test-firing the rifle, I was using the PSA-reccomended H buffer, since then, I swapped in an H2 and currently have an H3 installed. The H2 didn't seem to make much difference, but the H3 brought ejection from around 1:30-2 to ~3-4 o'clock. Not sure how informative that is...

I have attached pictures of the cratered/pierced XM80CL and of the OK Perfecta and Federal in case helpful. Some of the cases have significant ejector-swipe on them, this was from me playing with gas settings. Normal bolt holdback/cycling without ejector swipes was eventually obtained with the proper gas setting.

Thanks again to all who have read/responded!