Foxtrot Mike Buffer/Spring Question

[weirdharold]

I recently bought a FM 9.25" upper with a FM pistol lower. I removed the pistol buffer tube and replaced it with a mil-spec carbine tube(i.e. a SBR). I used the buffer and spring that came with the pistol in the carbine tube. The rifle has run perfectly with approx 1000 rounds of many types of ammo. The problem is the firing pin is dimpling the primers when the action is closed. Same problem with many brands of ammo and reloads. I'm worried about a slam fire. I have tried new factory firing pin and firing pin spring with same results. My question is: Do think that using the pistol buffer and spring as supplied by FM in the pistol in the carbine tube is causing the bolt to slam shut with too much force and causing the firing pin to dimple the primer? Anyone else have similar problems or any ideas? Thanks

 

Rich

[BelRiose]

It shouldn't matter as long as the tubes are the same length.

 

Since it's a full FM weapon, I'd recommend getting in touch with them and asking for advice. I've contacted them a few times, and they are super responsive and very helpful.

[Boxerglocker]

I run a FM-9 bolt in my AR9 build. When I originally first got it running with a standard 9mm buffer and spring combo. I noticed very slight dimple marks on the primers of ejected rounds. made sense to me as though the firing pin has a spring is is essentially free floating. I was just very careful to make sure the gun was always pointed in a safe direction when closing the bolt, etc. NEVER had a issue. Since replacing the buffer system with the Taccom 3 stage buffer system. I haven't noticed any dimples.