Almost put this in ammo and reloading but it’s really a technical question, not a reloading question.
I’m wondering what factors could be involved with causing the deflection strike higher on the case towards the shoulder rather than mid case as is usual.
Reloads: 1x fired LC 11 brass, 64 gr Gold Dot pulls from RMR, TAC powder running the hotter 5.56 data from Ramshot,
CCI #41 primers. Loading and shooting temps were above 80º from a few weeks ago. Loads were worked up,
these are just starting to flatten the primers. Next hottest load was a bit too much for my liking, settled on these.
Rifle: BCM BFH 14.5" Mid Length Barrel, VLTOR Low Profile Gas Block GB-2S, Battle Comp 1.5, BCM Bolt Carrier Group Auto (with BCM Extractor Spring Upgrade Kit ),
Colt H2 buffer, Tubb Flat Wire Buffer Spring. All riding on a Mega Upper/Lower billet set and a DD LITE 12.
The deflector on the Mega upper receiver is at a different angle than my BCM BFH 14.5" Mid Length Upper receiver but the Mega deflector is also shorter.
Not sure if that’s the only cause behind the different strike mark or not, so thought I’d ask if anyone has some ideas.
Not sure what the gas port size is on the BCM BFH midlength barrels.
I’ll have to take a different BCM upper (built by BCM) to the range as well, test them both and go from there.
Run some factory ammo first, then the reloads and see if that changes anything. Gotta start somewhere.
This is the cause of your issue. Too much weight and spring tension. Your rifle is more than likely properly gassed with a correct sized gas port. Spent cases are being ejected earlier than normal during the cycle due to the slowed rate of the carrier. Use a standard buffer.
Get rid of theTubbs spring and get a blue Springco spring, and use an H buffer. The port size of that midlength is around. 074-.076 off the top of my head.
