I have read every bolt jammed forward thread i can find and cant find an answer to my situation.  I ordered a new ranier arms ultramatch 20 inch 308 barrel for my dpms lr308 and got it installed yesterday.  If i load the magazine and pull the charging handle then release it, it loads the first round fine.  If i then pull the charging handle again, it ejects that round and will properly load the next.  Seems fine... but then if I fire a round, the bolt gets stuck forward and I had to beat the charging handle with a mallet to free it (tried everything else, nothing worked).  I tried again, same problem.  I tried a different brand of ammo, same problem.  What I have figured out so far is that the neck of the cartridge expands as the bullet is fired and is getting wedged inside the barrel.  So i only have the problem when a round is actually fired.  The extractor grabs the back of the fired cartridge amd the bolt is effectively stuck forward.  So the problem is that the case is getting stuck in the barrel.

I called ranier and they offered to take the barrel back and reream it.  Before I go to the hassle and expense of mailing it back and waiting on it, is there anything Im missing?  Is there any kind of bolt adjustment or anything that could be the problem?  Ill admit I didnt check headspace, but I dont really see how it would be a headspace problem.  It seems to be that the shoulder of the barrel is too tight?  As you can probably tell, Im still rather new to building and modifying firearms.  Im sure I butchered some terminology, but hopefully you understand what Im saying.

Thanks for the help!
J

It seems odd to me that simple case neck expansion is creating so much resistance to extraction that the bolt stays forward.  I would check the gas system thoroughly and look for leaks or problems.  Are you actually getting pressure to the bolt?  I'm not saying you're not right about the case being the issue, but it seems weird.  
I look forward to others' comments.

Its not gas system related.  Its not a simple failure to cycle.  The case is stuck in the barrel so hard i have to beat the charging handle with a mallet 8 or 9 times to get the bolt to budge.  Once it nudges the case back a half inch or so, then i can manually pull the charging handle and it ejects the fired case.

...edited for clarity....
It's best to check headspace any time a given bolt and barrel are gonna make love for the first time.

Correct.  It was so tight mortaring didnt work.  Took about 10 hits from a mallet.  I stood the gun on the stock, pointing straight up, and beat the hell out of the charging handle.  I then colored the neck of a new round with a sharpie and shot it.  By the time i got it out, there was no sharpie left right where the case begins to taper down.

I tried 3 brands of 308 then tried 7.62 to see if for some reason the barrel liked it better.  Exact same problem, and I would say equally as tight on both.

...edited for clarity....
It's best to check headspace any time a given bolt and barrel are gonna make love for the first time.

Who's ammo are you running? It sounds like the ammo headspace is too tall for this chamber. The round is binding against the bolt face causing everything to lock up. If you are reloading, your sizing die needs to be turned down some more. Trim length on .308 is 2.005". make sure the resized brass isn't any longer than 2.015" or you are over spec.

OP Can speak for himself, but has stated "Brands" twice; Once in the OP, and again in response to my query. I (ass)ume that means factory, not reloads.

Shut up 14'er..... beat ya to it!

Thats something I didnt think about... maybe the bolt is moving and its just slamming the expqnded brass back into the barrel.  Ill check the gas system in the morning and see

I think ill try shooting it without the gas block installed.  That should give me my answer, right?  Without the gas block there wont be any chance of the bolt moving back and pushing the expanded brass back in.  So, if the case still gets stuck than its a barrel problem.  If it doesnt get stuck, its gas system.

Watch out for the blast of really hot, really high pressure gas coming out that exposed hole in the barrel.



Jus' Sayin'





 

I checked the gas block and felt like it might be a little off.  Its also an adjustableso i opened it wide open.  The bolt fully cycled, but it didnt bring the case with it.  So now i have a case jammed in the barrel with one side mangled from the extractor ripping past it.  Still looks like the barreo is too tight?  I yad a 2 piece cleaning rod, so i put it down the barrel and hit it with the mallet, bent the rod.  So im ueaded to lowes to find a solid enough rod to use to try to knock it out

It's best to check headspace any time a given bolt and barrel are gonna make love for the first time.

Check out paragraph 2 here ---> http://www.forsterproducts.com/store.asp?pid=26983

Ill adjust it back down and see how it does.  The bore is spotless.

Just wanted to give an update incase anyone else has a similar problem amd is looking for a solution.  In the end, my gas block was a hair off.  The hole in the gas block overlapped the port in the barrel about 50 percent.  I got it 100 aligned and the gun functions flawlessly.

you did get the rifle to function, but I think there is a flaw in the chamber. when the case expands, the brass flows into or around the flaw and anchors itself. you may have intermittent problems with it, so if Rainier has offered to reream it, maybe it is a good idea. send the bolt along with the barrel so they can do a headspace check.