I got to thinking the other day....
When I reload I usually only neck size my fired brass. I have enough that none of it is past it's second firing yet so no problems there.
I noticed awhile back that in my 700 I could only load 4 rounds in the magazine and still have the top round feed reliably. If I loaded five the bolt would ride over the top round. (this was with the "tabs" on the follower ground off).
Now circumstances have changed and I have started shooting FGMM for department funded training and duty use. With FGMM I can load five and have the top round feed 100% of the time.
This got me to wondering. So I broke out the calipers last night. I found that about 5mm up from the head of the case the fired cases are .005" fatter than the new unfired FGMM. Now I didn't think that much of a variance would cause the failure, but that is about all I can lay it on since the dimensions are otherwise the same between the FGMM and my reloads.
When I install my Williams bottom metal I will most likely shim and bed it to account for the difference and allow my reloads to feed from the magazine.
Now my question is really two-fold. First, are the remington chambers excessively large in diameter? Second, how much clearance is necessary for 100% reliability in field conditions?
Just some things I am trying to wrap my head around while I plan for a future rebarrel.
It's amazing how much of the small stuff just doesn't matter when you are shooting an issued gun with issued ammo. I never sweated any of this stuff with my M40A1 and M852. I just knew I could load five and still close the bolt on an empty chamber. Never bothered to look at the brass after firing unless there was a failure.
When I reload I usually only neck size my fired brass. I have enough that none of it is past it's second firing yet so no problems there.
I noticed awhile back that in my 700 I could only load 4 rounds in the magazine and still have the top round feed reliably. If I loaded five the bolt would ride over the top round. (this was with the "tabs" on the follower ground off).
Now circumstances have changed and I have started shooting FGMM for department funded training and duty use. With FGMM I can load five and have the top round feed 100% of the time.
This got me to wondering. So I broke out the calipers last night. I found that about 5mm up from the head of the case the fired cases are .005" fatter than the new unfired FGMM. Now I didn't think that much of a variance would cause the failure, but that is about all I can lay it on since the dimensions are otherwise the same between the FGMM and my reloads.
When I install my Williams bottom metal I will most likely shim and bed it to account for the difference and allow my reloads to feed from the magazine.
Now my question is really two-fold. First, are the remington chambers excessively large in diameter? Second, how much clearance is necessary for 100% reliability in field conditions?
Just some things I am trying to wrap my head around while I plan for a future rebarrel.
It's amazing how much of the small stuff just doesn't matter when you are shooting an issued gun with issued ammo. I never sweated any of this stuff with my M40A1 and M852. I just knew I could load five and still close the bolt on an empty chamber. Never bothered to look at the brass after firing unless there was a failure.
