tcoz
Member
So, here's my issue. I'll give as much info as possible..
--Brand new 300 BLK upper, 16" MAS Defense barrel & gas tube, carbine gas
--Standard spring, standard carbine buffer
--YHM low pro gas block
--Existing 5.56 lower, standard PSA BCG and BCM Mod4 charging handle, approx. 500 .223/5.56 rounds through it--no malfunctions ever
--Brand new ALG ACT trigger, but 70 rounds of 5.56 fired flawlessly
Took it to the range for the first time and only had time to fire 30 rounds--15 from each of two Lancer 20rd mags using Fiocchi 150gr FMJBT ammo. Had four FTF's, click but no bang, always on rounds 2-15, never first round in mag. Bolt didn't lock back on either mag. After each FTF, charging handle pulled back easily and unfired cartridge was sitting on top of the mag. Seems like it might not be fully going into battery but that wouldn't explain the bolt not locking back.
Here's what I've done so far...
--Removed the extended bolt release/catch
--Checked trigger for correct installation but it worked fine with the 5.56 upper
--Purchased, lubed and installed PSA Premium BCG for use in 300 BLK upper
--Purchased, but haven't installed H buffer
--Purchased but haven't installed BCM extractor upgrade kit (actually for the 5.56 bolt since I doubt this has anything to do with my problem)
I think that's all of the pertinent background info. What does everyone suggest? Unfortunately, I live 45 minutes from the range and can only get there once every three weeks or so, therefore it isn't practical to make one change then test, then another change then test etc. I do plan on going this Wednesday though and will first try my Pmags and different ammo.
Thanks in advance guys.
--Brand new 300 BLK upper, 16" MAS Defense barrel & gas tube, carbine gas
--Standard spring, standard carbine buffer
--YHM low pro gas block
--Existing 5.56 lower, standard PSA BCG and BCM Mod4 charging handle, approx. 500 .223/5.56 rounds through it--no malfunctions ever
--Brand new ALG ACT trigger, but 70 rounds of 5.56 fired flawlessly
Took it to the range for the first time and only had time to fire 30 rounds--15 from each of two Lancer 20rd mags using Fiocchi 150gr FMJBT ammo. Had four FTF's, click but no bang, always on rounds 2-15, never first round in mag. Bolt didn't lock back on either mag. After each FTF, charging handle pulled back easily and unfired cartridge was sitting on top of the mag. Seems like it might not be fully going into battery but that wouldn't explain the bolt not locking back.
Here's what I've done so far...
--Removed the extended bolt release/catch
--Checked trigger for correct installation but it worked fine with the 5.56 upper
--Purchased, lubed and installed PSA Premium BCG for use in 300 BLK upper
--Purchased, but haven't installed H buffer
--Purchased but haven't installed BCM extractor upgrade kit (actually for the 5.56 bolt since I doubt this has anything to do with my problem)
I think that's all of the pertinent background info. What does everyone suggest? Unfortunately, I live 45 minutes from the range and can only get there once every three weeks or so, therefore it isn't practical to make one change then test, then another change then test etc. I do plan on going this Wednesday though and will first try my Pmags and different ammo.
Thanks in advance guys.
