At the range this morning working on the new 1100 yard steel and had problem. I have been shooting the same handload for 400 rounds. There is some primer cratering, no ejector marks. Ran 57 rounds today in total. Last two rounds I ran in rapid succession and the bolt was stuck closed, casein the chamber. Was easy to remove, but looks like it wend off slightly out of battery. It didn’t go shoot until I pulled the trigger, not a slam fire. Thoughts?
AR10 Out of Battery?
- Thread starter Silverjay
- Start date
An AR firing pin cannot reach the primer if the gun is out of battery.
Where the brass is expanded is as far as it goes into the chamber, drop a sized piece of brass in the chamber and look.
You have an overpressure situation that could be caused by several things, (listed in probable most likely order):
Powder Overcharge
Insufficient case neck tension allowed bullet to be pushed into case during firing sequence
Oil/water in chamber
Bore obstruction (did the cartridge immediately preceding have a light powder charge? I've also seen bullets have the center lead blown out and leave a jacket in the bore...look at your bore carefully, run tight patch on a cleaning rod and check for loose spot in bore... would be past gas port since gun cycled)
Accidental heavier bullet substituted
Bad/soft piece of brass
Probably a few more I can't think of right now.
WEAR SAFETY GLASSES!!!
Where the brass is expanded is as far as it goes into the chamber, drop a sized piece of brass in the chamber and look.
You have an overpressure situation that could be caused by several things, (listed in probable most likely order):
Powder Overcharge
Insufficient case neck tension allowed bullet to be pushed into case during firing sequence
Oil/water in chamber
Bore obstruction (did the cartridge immediately preceding have a light powder charge? I've also seen bullets have the center lead blown out and leave a jacket in the bore...look at your bore carefully, run tight patch on a cleaning rod and check for loose spot in bore... would be past gas port since gun cycled)
Accidental heavier bullet substituted
Bad/soft piece of brass
Probably a few more I can't think of right now.
WEAR SAFETY GLASSES!!!
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Check your loaded rounds by trying to push the bullet into the case. Push the bullet hard against a piece of wood.
If the cases have been loaded a few times and necks not annealed, it could be a problem.
You could have even had a case neck split and not noticed it, but it would be visible on the fired brass.
If the cases have been loaded a few times and necks not annealed, it could be a problem.
You could have even had a case neck split and not noticed it, but it would be visible on the fired brass.
Could be powder related, but I don’t know how. Every charge is done on an auto trickler, and checked for fill height. I have seen the trickler over run bu 0.06 grains, but not more. Might be neck tension, these are 1x fired to be annealed next run. If I put my body weight on the I get 0.002” change in length. Chamber is dry, bore looks good. Preceding round impacted on steel at 1100 so I doubt the charge was off or the bullet came apart. No evidence of necks splitting.
What load are you running? I can check it on QuickLoad, you may be running on the edge of over pressure. I'll need ALL the specs, including water capacity of case (weigh once fired case before filling with water, then after, subtract, need water weight in grains).
Does all the other fired brass look normal? Measure case head expansion (directly above the extractor groove) compared to new brass and if you have ANY, it's too hot for an AR (or brass is bad, not common, but possible).
Bores change after 5-6k rounds on a bbl. and what was safe earlier may not be good now. Have any of your dope comeups changed? (indicative of bore wear/velocity change).
At least you have an unusual cartridge for your bullet board.....a .308 Belted Magnum!
Does all the other fired brass look normal? Measure case head expansion (directly above the extractor groove) compared to new brass and if you have ANY, it's too hot for an AR (or brass is bad, not common, but possible).
Bores change after 5-6k rounds on a bbl. and what was safe earlier may not be good now. Have any of your dope comeups changed? (indicative of bore wear/velocity change).
At least you have an unusual cartridge for your bullet board.....a .308 Belted Magnum!
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I get 59,329, but left default of 2.800 on OAL (you're probably a little longer).
It's warm enough that you have to be careful with an AR, any small mess up would get you what happened.
I charge 50 at a time in my loading block, then angle the cases slightly so the fill level is just visible and check every case.... under a good light!
Check for case head expansion, ANY AT ALL and you need to back off a few tenths. Some brass is softer (Hornady, Rem., and Nosler) and won't take close pressure after a loading or two.
The 8208 is pretty slow and you are a little high on port pressure, (I'm assuming a rifle length gas system, an adjustable gas block would be good, if you don't have one, if carbine length...you need one badly!)
Looks like you're doing all the right stuff...probably just a somehow slightly overcharged case or maybe they dropped a 185 in the box by mistake.
It's warm enough that you have to be careful with an AR, any small mess up would get you what happened.
I charge 50 at a time in my loading block, then angle the cases slightly so the fill level is just visible and check every case.... under a good light!
Check for case head expansion, ANY AT ALL and you need to back off a few tenths. Some brass is softer (Hornady, Rem., and Nosler) and won't take close pressure after a loading or two.
The 8208 is pretty slow and you are a little high on port pressure, (I'm assuming a rifle length gas system, an adjustable gas block would be good, if you don't have one, if carbine length...you need one badly!)
Looks like you're doing all the right stuff...probably just a somehow slightly overcharged case or maybe they dropped a 185 in the box by mistake.
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Is that a 308 case? Damn. If so, that's some serious pressure. I'd guess a heavier bullet made it into the box too. Or accidental overcharge by a few grains.
Glad you made it through that one unscathed!
Glad you made it through that one unscathed!
That looks like the new 308 belted magnum.
Weird, it just seems almost impossible to have enough pressure to expand the head yet the primer did not blow out.
Is it possible the reloading die did that when you resized the case and you missed it.
Weird, it just seems almost impossible to have enough pressure to expand the head yet the primer did not blow out.
Is it possible the reloading die did that when you resized the case and you missed it.
Is the case body all gouged up or is that reflections?
If it didn't FIRE out of battery, it unlocked and the case was stuck.
That is almost a head separation.
Could the bolt have opened then slammed back on the case?
If it didn't FIRE out of battery, it unlocked and the case was stuck.
That is almost a head separation.
Could the bolt have opened then slammed back on the case?
No matter what the pressure is if that that round burned its powder while still in the chamber you would not get case expansion like that. Especially since that low on the case the expansion is happening in the web. The reason I say if if was in the chamber went the round reached max pressure the chamber would not have allowed expansion with that sharp of a step in it especially in the web.
Maybe the firing pin on AR's won't allow an out of battery ignition, I am not qualified to argue that point, but I will sk is this true with all flavors of the 308-sized rifles since there are so many different proprietary designs.
I don't see this due to case head separation as it is too far down on the brass and it does not cause the case to expand in diameter, and is more often a result of pushing the shoulder back ttoo far when resizing than pressure.
Maybe the firing pin on AR's won't allow an out of battery ignition, I am not qualified to argue that point, but I will sk is this true with all flavors of the 308-sized rifles since there are so many different proprietary designs.
I don't see this due to case head separation as it is too far down on the brass and it does not cause the case to expand in diameter, and is more often a result of pushing the shoulder back ttoo far when resizing than pressure.
The over pressure caused the brass to expand past it's elastic limit to the unsupported head of the case, it was jammed tight enough to not allow the bolt locking lugs to disengage when the gas from the gas tube tried to start extraction.
Kinda like a bolt gun gets an over pressure load and you have to beat the handle up with a stick...same thing here, there is only so much power available in the pressurized gas tube to unlock the bolt.
Pull out your BCG and play with it a little and you will see it is not possible for an AR firing pin to protrude enough to hit the primer unless the bolt is fully turned and in battery....and yes, this pertains to all flavors of rifle caliber AR's with rotating bolts, big and small. Of course, pistol calibers are different, and also the CMMG Guard.
While it's out, drop a round in the chamber and see how much case head sticks out unsupported, it's exactly where his head is expanded in the pic above. I've seen dozens of these, usually with a hole blown out the side of the case head. He was lucky, if it was a few PSI hotter, he may have had a mess, i.e. blown out magwell, ruined magazine, possibly ruined bolt and barrel extension....maybe injuries.
WEAR SAFETY GLASSES!!
Kinda like a bolt gun gets an over pressure load and you have to beat the handle up with a stick...same thing here, there is only so much power available in the pressurized gas tube to unlock the bolt.
Pull out your BCG and play with it a little and you will see it is not possible for an AR firing pin to protrude enough to hit the primer unless the bolt is fully turned and in battery....and yes, this pertains to all flavors of rifle caliber AR's with rotating bolts, big and small. Of course, pistol calibers are different, and also the CMMG Guard.
While it's out, drop a round in the chamber and see how much case head sticks out unsupported, it's exactly where his head is expanded in the pic above. I've seen dozens of these, usually with a hole blown out the side of the case head. He was lucky, if it was a few PSI hotter, he may have had a mess, i.e. blown out magwell, ruined magazine, possibly ruined bolt and barrel extension....maybe injuries.
WEAR SAFETY GLASSES!!
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PS...Also check your bolt rings and gas tube for damage or looseness at the gas block. Also your extractor (may be bent) and spring.
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