Ok, close inspection with bolt components looks ok. All clean, ejector moves freely, extractor, no chips, spring with insert/o-ring ok. Chamber is clean, no burrs, etc. Carrier key/screws tight/staked properly entire system cleaned/lubed. As a note, I have alot of time on the AR platform, never seen this with 5.56 based guns.
Rifle-used, 200 rounds fired, previous owner stated no issues with gun at all. No modifications to gun, no odd marking on brass ejected. Same occurance with either factory or tested reloaded rounds. Components were properly sized LC and Hornady 150 FMJBT/165 SST H4895 and IMR4064. Charge weights adjusted for Mil brass, no over pressure rounds. Factory was FGMM/175, Blackhills Match 175, XM80(149 ball) Federal Fusion 150 and Federal 165 Deer Thugs. On the factory FGMM/Fusion, I could tell by recoil and fired casing, that they slightly over pressure.
Magazines were both generations of Magpul's and one each 10 and 20 round ASC, all experienced same issue. Multiple loaded mags, had no issues with function, always last round. I started thinking that maybe the follower was interferring with the bolt in some manner, so I would chamber a round, remove the magazine and fired round would be caught in port by bolt, always neck out first. This is maybe a 1-2 in 10 occurance(mag in/out). I tested bolt lock with one in the mag(all mags) and had no issues on first test rounds.
The only thing I can think is happening is maybe shooter related. I may be relaxing my position knowing it's the last round and not giving a solid platform for the gun to operate?. It is a light .308 and depending, some light guns, including pistols can experience this issue.
In the grand scheme of things, if it's always the last round, I would be dropping the mag and the case falls out with it, not the end of the world.
On a good note, 3/4" with a certain charge weight of the 165 SST, 4x scope.
Appreciate any feedback
Mark
Rifle-used, 200 rounds fired, previous owner stated no issues with gun at all. No modifications to gun, no odd marking on brass ejected. Same occurance with either factory or tested reloaded rounds. Components were properly sized LC and Hornady 150 FMJBT/165 SST H4895 and IMR4064. Charge weights adjusted for Mil brass, no over pressure rounds. Factory was FGMM/175, Blackhills Match 175, XM80(149 ball) Federal Fusion 150 and Federal 165 Deer Thugs. On the factory FGMM/Fusion, I could tell by recoil and fired casing, that they slightly over pressure.
Magazines were both generations of Magpul's and one each 10 and 20 round ASC, all experienced same issue. Multiple loaded mags, had no issues with function, always last round. I started thinking that maybe the follower was interferring with the bolt in some manner, so I would chamber a round, remove the magazine and fired round would be caught in port by bolt, always neck out first. This is maybe a 1-2 in 10 occurance(mag in/out). I tested bolt lock with one in the mag(all mags) and had no issues on first test rounds.
The only thing I can think is happening is maybe shooter related. I may be relaxing my position knowing it's the last round and not giving a solid platform for the gun to operate?. It is a light .308 and depending, some light guns, including pistols can experience this issue.
In the grand scheme of things, if it's always the last round, I would be dropping the mag and the case falls out with it, not the end of the world.
On a good note, 3/4" with a certain charge weight of the 165 SST, 4x scope.
Appreciate any feedback
Mark
