Do you mean a cartridge got jammed in the chamber?
What happens when it jams? Is it failing to extract, or eject?
Around got stuck in the chamber?Did you use a chamber brush before attempting to fire the weapon?
Stuck in the barrel? Is it a chrome lined barrel?
There are some sites with good technical information - I might suggest www.ar15.com for a look at their technical forums. However, if you are not comfortable fixing it yourself any competent gunsmith can probably diagnose and fix the problem fairly quickly.
Get your micrometer and measure the ammo. Check it against specs.
How old is the ammo and who manufactured it?
Is the chamber bright and shiny clean?
I just got a DPMS that works well. Admittedly, there are some questions about the efficacy of their quality control. Might want to make sure the gas tube is in there properly and there are no obstructions in the gas hole on top the barrel or in the gas block. Sounds to me more like the thing isn’t cycling.
Also, if the round only goes part-way down the barrel, that indicates the problem is possibly the ammo. My favorite ammo is the PMC stuff, but also CBC/Magtech is good.
A picture of the brass that got stuck will tells us a lot. As it is, it could be any number of things.
Stuck/broken extractor. Spring missing from under extractor. Bad ejector or ejector spring. Gas system not fully cycling. Improper buffer or buffer spring installed causing a short stroke condition. Cracked gas tube.
Need more info.
I don’t care for DPMS for many of the same problems.
I have a DPMS, Sig, and a Windham CDI. In order of quality, it’s Windham, Sig, then FAR, FAR below DPMS.
I was having failure-to-feed on the DPMS, and realized it’s very finicky about mags. The metal one that came with it just didn’t work, and I switched to one of my Magpul, which decreased the issue markedly, but it still happens.
Plan on unloading it.
Look on the lower and barrel and see if it is rated for. 223 only or 5.56. Shooting the former in the latter can cause problems. (The reverse is fine though.)
Inspect the extractor and spring for damage and serviceability.
I was told DPMS stood for Didn’t Pass Military Specs
Usually when I’ve encountered this type of complaint, it was caused by firing a NATO 5.56 round in a .223 barrel. The leade is much less in the .223 barrel. If you fire a 5.56 NATO round in a .223 barrel, the pressures caused by the projectile encountering the rifling so “soon” cause the pressures to spike. A lot of times, the primer will pop out and jam the gun. DO NOT assume the jockey at the gun store will know this or that the barrel or ammo are marked correctly.
What weight bullet are you using. I once had a DTMS that wasn’t happy with 55 gr. . I would give it a good cleaning including the gas tube. If it has an obstuction not enough gas will go though it to operate the action.
Sounds horribly flippant, and not meant with any hostility whatsoever, but not to worry. NJSP may be stopping by in the next couple of months and relieving all folk of their functioning/non-functioning “evil” rifles.
On the advice side, find someone face to face, who knows what they are doing, and get that rifle into service! If it is sitting in a dealer’s shop when the hammer comes down, that will be the last time it sees the light of day.
Round gets stuck midway down the barrel (before reaching the gas port?), sounds like the bolt is not locking up entirely. Could be head-space issue, roughness in the bolt carrier cam path, get a head-space gauge and verify chamber dimensions (Brownells).
Fire a buddy’s AR with similar ammo. If yours felt markedly different (presuming a round goes downrange), down-check the rifle and turn-to with the troubleshooting.
Before “the craziness of 2013” there were more options. Now, hold what you have, make it work, stock up on ammo.
Good luck!
5.56mm or .223 chamber?
5.56mm or .223 ammo?
Brass or steel ammo? Some chambers are too tight for steel, which is not as soft as brass. Some rifles shoot steel or brass shells all day, some hate steel and digest only brass.
I had a Bushmaster that would get steel cased cartridges stuck every time. Solution: no more steel cased ammo! (Wolf, etc.)
Check the bolt carrier key (the hollow, forward-facing horn on the top of the bolt carrier) for ANY sign of movement or looseness. A loose key is the main reason a new gun will fail to cycle. If it is loose, get an allen wrench, tighten it up (a good “hmph!” tighter than snug but don’t go crazy and wring off the heads) and stake both screws tight with a punch. They will have been staked at the factory, but in my experience this operation is not always successful. If they aren’t staked rigt, they will come loose again right away, often on the first shot.
More about the ammo, please. The possibility of your DPMS being out of spec is not the cause of a stuck projectile in the bore. That's a squib load, sir.
Many lots of Federal XM193 and pretty much all Federal AE223BP is absolute rubbish. I know that ammunition is hard to come by right now, but you need to find quality 5.56mm ammo like Hornady GMX Superformance or Hornady TAP, Black Hills, Silver State, or premium Winchester Q3131 and use that at the range before you blame DPMS.
You didn't specify what barrel twist rate you have, but I'd expect that it's going to be 1x9 or 1x7. In either case, use ammunition with 62gr projectiles and report back to us.
You need to examine your ammo, magazine, and then the rifle in that order.
Your fired casings from your last range trip would probably tell a lot more of your story. I have great suspicions about this Federal '223' ammunition you have. If you bought it in loose bulk pack of 1000 rounds, come back and tell me what the carton says. If its XM193, you will see the lot number printed on the face of the individual 20-round boxes.