That’s a classic sign of over-gassing and/or a rough or dirty chamber. Cheaper AR-style rifles like the DPMS Oracle often come from the factory with fouling left over from the manufacturing process, and that fouling can make it into the chamber. If you didn’t clean the chamber with a chamber brush before you shot the rifle, that could be part of the problem. You might need to polish the chamber also, but making sure it’s clean is the first step.It was a stuck case. Part of the rim was torn off.
Beating on the charging handle will break it. If the case doesn't extract using the pogo maneuver, pogo harder until either the extractor jumps the rim (which usually means the extractor spring is weak) or the extractor tears the rim off. Once that happens, insert an empty mag, lock the BCG back and drive out the stuck case with a long one piece rod, preferably one made of brass. Don't use a hammer. Simply toss the rod down the bore repeatedly until it knocks the case out.I had a similar issue with my AR-15 a short while ago and the gun was endlessly mortared by myself as well as several range officers (and I don't disagree with the method generally). However the bolt never moved more than a quarter inch and I ended up having to case the gun and take it home with a live round in it. A friend and I wound up using a mallet to drive the charging handle to the rear. No damage noted and it only took one or two whacks to get it open. Just something to think about for those who haven't tried it.
That’s a classic sign of over-gassing and/or a rough or dirty chamber. Cheaper AR-style rifles like the DPMS Oracle often come from the factory with fouling left over from the manufacturing process, and that fouling can make it into the chamber. If you didn’t clean the chamber with a chamber brush before you shot the rifle, that could be part of the problem. You might need to polish the chamber also, but making sure it’s clean is the first step.
Also, cheaper AR-style rifles almost always come from the factory with lightweight buffers since steel is a lot cheaper than tungsten. And that means they are often over-gassed for the buffer weight. This causes the bolt to unlock early, which means the extractor is trying to pull the empty brass from the chamber when the gas pressure is still high and the brass is still expanded against the chamber walls. This can cause the empty brass to get left in the chamber, and a rough or dirty chamber makes this even more likely to happen. The torn case rim from the extractor is a dead giveaway. Now, usually when this happens the bolt doesn’t get stuck shut like yours did, so I’m guessing you’ve got a chamber that’s rougher or dirtier than normal.
To address the over-gassing problem, switching to a heavier buffer will slow the unlocking process down and will make extraction smoother. Installing an adjustable gas block would be an even better fix, but changing to a heavier buffer is a lot easier so I recommend doing that as a test before you decide to get an adjustable gas block.
GottchaIt jams the case in harder.
Well, not really; in the op's case it just doesn't do anything. FA is used to close the bolt on a recalcitrant round, but in the case of a double feed or some other malfunctions use of it will make a inconvenient jam turn into a truly nasty one.
Agreed. It's just that I've seen more issues with the lower-end ARs when it comes to debris in the chamber. I'm not referring to the sticky preservatives you get in rifles like a Colt, I'm referring to metal shavings left over from the manufacturing process. For example, I've seen more than one M&P Sport with aluminum shavings all over inside the rifle. And that's fine with me: If that's part of the cost savings of an otherwise good rifle, then that's a small price to pay. But a new owner should make sure to clean it out first.I have always found it a good idea to clean all new guns --- even high end ones. Finding residue in chambers and barrels isn't limited to cheap ARs. Even better rifles I have have had residue .... a lot of times it's preservative if the rifle was made oversees.
I disassemble all new or new to me firearms ,clean ,lube and reassemble before first range sessionAgreed. It's just that I've seen more issues with the lower-end ARs when it comes to debris in the chamber. I'm not referring to the sticky preservatives you get in rifles like a Colt, I'm referring to metal shavings left over from the manufacturing process. For example, I've seen more than one M&P Sport with aluminum shavings all over inside the rifle. And that's fine with me: If that's part of the cost savings of an otherwise good rifle, then that's a small price to pay. But a new owner should make sure to clean it out first.
I've seen lots of issues with customers at the ranges where I've worked who had new, lower-end ARs that didn't function because they weren't cleaned and lubed first, but maybe that was simply because new AR owners who don't know they should clean their rifle first are more likely to be buying lower-end ARs as their first rifle? Either way, I agree that it's generally a good idea to clean a new firearm before you shoot it, especially an AR. And I'll admit that I've seen higher-end rifles like Colt and Daniel Defense not work properly if not cleaned and lubed first before firing.