Question about some failed reloads (.308 win)

[coyote tech 421]

It is possible that the bolt was not fully forward with a M14/M305. The force of the hammer on the firing pin is reduced because it is expended moving the bolt that last few thousandths of an inch. If that is what is happening, a good cleaning and lubing will cure the problem.
Pat

 

[bellracer]

On the other hand, “excessive” headspace could be to blame.
- Remove ejector, firing pin, trigger group, and return/action spring (clean the FP hole).
- Reassemble without those parts.
- Slowly chamber your ammo, and if it chambers and easily locks up, then insufficient headspace and bullet seating is not your problem.
- With a chambered round put your fingers at the rear of the bolt, top and bottom. If you can get lots of “wiggle” up and down, and side to side, there may be too much headspace.
- Try backing off your sizing die till you get only a little up and down rear bolt movement. That is about right for that type of action and it will probably increase your accuracy and improve case life.
- Most Garand and M14 target shooters seat their bullets as far out as possible without touching the rifling, keeping in mind that this “raises” pressures.

 

[cosmic]

Well - OAL may or may not be contributing to your firing issues, however, you should not use "factory ammo" OAL specs for reloads - especially when you start going beyond the cannelure. Different bullets have different ogive profiles, even in the same bullet weights. You can see this just by looking at various bullets Thats why the cannelure is there.
Reloaders striving for accuracy will do a physical survey of the chamber on their rifle to establish an OAL that will put the bullet relatively close to the rifling - say 1/32 of an inch or less. This can be a dangerous game, as firing pressures increase substantially if the bullet gets too close to the rifling.
Take one of your offending reloads, stick the bullet in the muzzle until it hits the rifling, and scribe a line. (Not sure if you can do this on an M305, but any 308 bolt gun will do.) Measure from case base to the line. Compare this dimension to factory ammo, and other reloads, and you'll get an idea of where you stand. In any event, I would bump any remaining ammo down to the cannelure.
Otherwise, I think folks have identified all the possible culprits -- OAL too long, brass too large, or too small, hard primers, weak firing pin.

 

[tree mugger]

The FTF rounds look as though they were struck by the firing pin as the rifle pick the rifle up from the mag and went into battery (M305s have a free float firing pin).

To me it looks as though the rifle never went into battery.

As an aside.....I would suggest that you get some CCI #34 primers. They are in a white box. The difference between them at the WLR is that the CCI #34's are harder. They are specifically made for semi's that have a free float firing pin. This is to help avoid slam-fires.

 

[fogducker]

im a newbie at reloading....but from the pics you show of the miss fired primmers.they look they are inbedded in to far...is this possible all?

 

[island]

Many thanks for all the excellent advice here - the problem appears to have been the seating depth of the bullets after all. I went back and re-seated the ones that did not fire as well as the remainder of the (small) batch, and got to the range a couple of days ago.

Everything fired just fine this time, including the 4 that did not first time around! Had one eject problem, but it was just the brass choking on the scope mount, nothing (I think) to do with the ammo itself.

The empty cases look fine, no sign of problems, and the firing pin indent appears normal now.

Thanks again all!