05-16-2011, 12:05 PM
osage Wrote:LR1955, yes. I went and pulled the target down too. I had loaded 3 rounds in the mag, there are 2 holes in the target. I had assumed it was the 2nd round that blew up but being as I could find all the pieces of the follower but not the loaded third round I am pretty sure the third round blew up while being chambered. Its the only thing I can come up with that makes sense.
Osage:
Yes, you had an out of battery firing.
I note you were using the 120 grain Hornady AMAX and the Federal Gold Medal Match primer.
I have never had a out of battery firing with the Federal GM primers in any rifle and I have shot many thousands of rounds of hand loaded ammo out of bolt and gas guns using Federal GM primers without any problems what so ever so I discount the primer itself.
When I seat primers, either using a progressive press or using a hand seater, I visually inspect the case to ensure the primer is seated just below the rim. A primer that protrudes from the brass is prone to going off when a bolt hits it on closure. If you do not have a procedure in place where you visually inspect every cartridge you load to ensure the primer is seated below the base of the rim, you should initiate one.
Finally, the 120 Amax bullet we have noted not to be ideal for the Grendel due to the ogive design. The ogive design is tangent and guys have said they had to seat the bullet so deeply into a Grendel case that the neck sometimes protrudes past where the shank and ogive meet. This is way deep but they had to because the Grendel chamber is cut very short. The 120 Amax is not a good choice for the Grendel as they end up having to jam it into the lands or seat it so deeply that it eats up powder space. Either way you are talking huge pressure spikes.
If you seated your 120 Amax bullets without paying attention to how close they were to the lands, after ten or fifteen firings enough crud will have built up in the chamber to give the conditions where the cartridge isn't going into battery enough to be safe.
Combine this poorly designed bullet for the Grendel plus the potential that you had a primer which wasn't seated deeply enough and add the intertial firing pin of the AR series of weapons and you have the ingredients for an out of battery firing.
Case closed.
LR1955