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Posted: 6/13/2003 7:13:13 PM EDT
First off, my apologies for coming onto the board with a problem right off, it's been a while since I've been an AR owner and I didn't own my first one long enough to really get into the community. Guess this one decided to give me a jump start into it B-)

Anyway, when I was zeroing her Tuesday, I got done doing it, then let a friend shoot it. Being cursed by fate, about every time he shot a string of ten or so, a spent case would hang up in the chamber. The bolt would cycle fine, ripping the extractor right off the rim and tearing it up enough that trying to get it out by snapping the bolt back over it was futile. Pushing it out with a rod, though, easily got it out, with no extraneous effort at all, matter of fact the weight of the rod was usually sufficient. It didn't seem to happen in rapid fire. And although it happened quite often when my friend fired it, it took me ninety rounds of shooting from the bench to induce it. Never happened when I shot standing.
The rifle is a PWA lower with a DPMS A3 upper, 14.5" bbl, A2 flash suppressor, and collapsible stock. Ammo was PMP 55 grain FMJ, which clocked out that 2950 give or take over my chrony. Tight chamber maybe? Needs a bit of polish? The barrel is chrome lined, as far as I can tell. The chamber throat is silver and the muzzle has the silver starburst that I was told back in the day indicated chrome. Chamber's 5.56 according to the markings on the barrel.

I appreciate any advice anyone might give. Hopefully I'll be less of a leech in the future and actually be able to contribute something around here B-)

XH1927
Link Posted: 6/13/2003 9:06:52 PM EDT
The chamber needs to be fully cleaned, then maybe polished if cleaning does not solve the problem. The best way to final chamber clean is to spin a 30 Cal mop in the chamber that has been soaked with CLP. This will clean out any fouling that may have been collected (not been cleaned) at the neck to case mouth edge cut. If the fouling at this area is not cleaned, it will make the standard ammo show signs of over pressure, and could be the problem your having with the rifle. As for the extractor, if it's ripping the rim on the case, it's fine. Also, PMP ammo is under loaded, and the barrel is a DPMS so the problem lies in the chamber. Also, Your downfall to chamber polishing by hand is that the chrome lining is a bitch to polish (it can be down, but after you have some experience doing so). Lets just start with a good cleaning and see if that resolves the problem.
Link Posted: 6/14/2003 4:44:50 AM EDT
What Dano says is all true. I would try polishing the chamber. Something to consider... The collapsable stocks use a lighter buffer which causes the bolt to recoil faster. If you have one of those plastic bb filled buffers throw it out and get a metal one. The H marked buffers (recomended) weigh 3.8oz compared to 2.9oz for the standard buffer and 1.8oz for the plastic one. A fixed stock buffer is 5.3oz and a bolt and carrier weigh 11.4oz.
Link Posted: 6/14/2003 5:05:54 AM EDT
Dano's right on the money, as always. Try cleaning the chamber and see if it helps. I'm concerned that it's more than that tho. If you're running a 14.5" barrel with a tight chamber then the problem MAY be too much gas. Basis of concern; Generally, rough chambers (like ringed or gouged ones) will still try to hang onto the brass when you knock it out with a rod. Guns suffering from over function don't, many times the brass will drop out if you hold the bolt to the rear and give the piece a firm shake. Solution, Could be much more complex, esp with the chromed chamber limiting you rechambering options.Just FYI, so you won't be shocked. Try cleaning it per the book then get back to us.
Link Posted: 6/20/2003 9:58:13 PM EDT
Thanks for the help, everyone, I appreciate it. I tried thoroughly cleaning the chamber just as recommended, and got the malfunction again on my 32nd round the next time I was at the range. It was somewhat harder to get the case out this time. One thing I forgot to mention before is the bolt unlocks and retracts with almost no drag when no round is present, but with a fresh, right-from-the-box round in the chamber, it takes more effort (nothing strenuous, but perceptible) to draw back after the bolt unlocks and I actually start pulling the round out of the chamber, another reason I suspected a tight chamber to be the culprit originally. I also checked my buffer per oldguy's advice. It is in fact, metal. However, I can find no evidence of an H, and it feels very light (subjective measurement, unfortunately... I don't have a scale that'll measure in ounces). Would you recommend that I obtain an H Buffer before taking any further action? XH
Link Posted: 6/21/2003 7:32:31 AM EDT
[Last Edit: 6/21/2003 7:33:38 AM EDT by Tweak]
XH Do you have .223 headspace gages? Your best bet may be to return the rifle, or upper, to DPMS for warranty repair.
Link Posted: 6/21/2003 9:34:50 AM EDT
Ditto with tweak!!!!! Get DPMS on the phone and have them resolve the chamber problem. Note: On a few recent DPMS barrels, I have had to polish the chambers to get the barrel running. Seems that even though DPMS chamber 5.56, they are on the tight side in regards to the chamber sidewall dimensions. Since your chamber is chromed plated, reaming is out of the question because you would remove the chrome plating in areas, and polishing out the chamber would leave the chrome too thin and may flake.
Link Posted: 6/21/2003 10:07:08 AM EDT
I have to agree with the others. Probably should contact DPMS and possibly send it back. A heavier buffer is just something to try.
Link Posted: 6/25/2003 3:13:49 PM EDT
[Last Edit: 6/29/2003 11:58:15 AM EDT by WFO]
After about a year i broke out a new 16" upper i got from DPMS that i had stashed back .. Had several failure's to extract in about 400 rds . I went through all the motions of cleaning , Checking head space , ect ect When i got down to the nitty gritty seams the chamber was reamed by a bad reamer , Chamber is full of ridges the entire length . I Contacted DPMS about this but of course i waited to long .. Warranty wont cover it But im gonna send it back to them to be re-barreled anyway [img]http://www.gunsnet.net/album/data/500/3911DPMS_Chamber_Ridges.jpg[/img]
Link Posted: 7/4/2003 5:39:08 PM EDT
Holy cow, that is bad, never seen a chamber like that, seems they should have caught that at the factory. I am not the sort to complain, but WFO, if you haven't talked to them about it already, I would call them and politely tell them about your problem and see if they will fix it for free.
Link Posted: 7/5/2003 3:39:42 AM EDT
WFO, i'd say a picture is definately worth a thousand words in your case. That is obviously a problem at their end. Have you posted over at the industry board? I think you should email them that picture.
Link Posted: 7/5/2003 3:52:13 PM EDT
I have contacted DPMS about this problem .... I got three different answers on their warranty from three years all the way down to thirty days ? Last person I talked with wuz Dave in returns ..he says thirty days ... sent it back and he will look at it and see what he can do with it I tell him the chamber looks like its been reamed out with a masonry bit ! ( Not much you can do with that HUH ! ) if we have to re-barrel , its gonna run around $175 .( No doubt ! ) I sent it back over nite .. with original box and invoice ,, hadn't been outta the box thirty days ! We will see what happens with it .. But one thing is guaranteed .... if the do charge me for their screw up ... they will never get another penny from me and I will bash them every chance I get ! the more i think about this the madder i get
Link Posted: 7/5/2003 3:57:58 PM EDT
Originally Posted By curt: WFO, i'd say a picture is definately worth a thousand words in your case. That is obviously a problem at their end.
View Quote
Might use that pic as my Avatar ! [:D]
Link Posted: 7/6/2003 12:07:31 PM EDT
WFO, DPMS should stand behind their product. A 30 day warranty is Bull! I'm going to get a 20" preban upper for my bushmaster. I was thinking about a DPMS one from CMMG. But, if they don't correct your problem, I'll go with a Bushmaster instead.
Link Posted: 7/6/2003 2:16:48 PM EDT
Originally Posted By bnz42: WFO, DPMS should stand behind their product. A 30 day warranty is Bull!
View Quote
That's kinda what i thought .. But like i stated before i talked to three different people and got three different answers ! ? Kinda make's ya wonder bout them . But i will give them the benifit of doubt till i call them and check on the status of my upper .If they have any common sense about them , when they look at the chamber they will know they Bucked Up ..
Link Posted: 7/7/2003 9:55:19 PM EDT
WFO, Keep us updated, I doubt that a chamber reamer would be able to clean that up unless the chamber is considerably undersized. It may be worth a try if you get no satisfaction from DPMS and the bore isn't chromed tho.
Link Posted: 7/9/2003 3:50:53 PM EDT
Update ! .. I go into work today and low and behold the up's man is waiting at the gate for me .. Im like , wtf im not expecting anything ? Package from DPMS he says ! I sign off, rip the box open ,, My upper has been re-barreled Good Deal , Quick turn around time too (8 days) Total on invioce $0.00 I will continue to do business with them Thank You DPMS . J Stewart ...
Link Posted: 7/10/2003 4:12:23 PM EDT
Update #2 300 rds LC burnt up 200 rds misc. crap IMI Win SA No Errors ... Runs Great and just 3 clicks on the reflex to get it back in
Link Posted: 7/10/2003 5:22:05 PM EDT
Ah, nothing like a happy ending to a story. Er wait, did the original poster ever solve his problem? Well here's hoping things turned out for him as well, heh.
Link Posted: 7/13/2003 6:13:01 AM EDT
Are any of these trouble DPMS uppers of the CMMG variety? I've only heard good things about the CMMG/DPMS...so far.
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