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Posted: 1/5/2006 4:27:00 PM EDT
Ive got problems shooting ammo through my DCM rifle. Only commercial ammo that goes through it is Federal and Black Hills. I mean this is the ONLY commercial ammo that will continue to feed and function in it. Quality Surplus M855 and M193 will work too.

But nothing else. Ive tried Winchester, Remington, Wolf, S&B, PMP, PMC, Santa Barbara, Olympic, you name it. Everything jams up within a few rounds. Except for PMC that will go about 30 before jamming, and Santa Barbara that gets stuck in the chamber on the first shot. I need to smack out the round with a cleaning rod to get that Santa Barbara.

Anybody else had similar issues with DCM/CMP barrels?
Link Posted: 1/5/2006 5:26:03 PM EDT
It sounds like you may have insufficient headspace. Also, the throat of the chamber may be too short.
You need to check HS with a 'GO' gauge and the bolt stripped. IM if any questions. Charles the Gunsmith.
Link Posted: 1/6/2006 5:51:38 AM EDT

Originally Posted By 1911builder:
It sounds like you may have insufficient headspace. Also, the throat of the chamber may be too short.
You need to check HS with a 'GO' gauge and the bolt stripped. IM if any questions. Charles the Gunsmith.



Sounds right. I did some reading on this. Bushmaster sent me back a response when I asked about their chamber when I considered buying another barrel. The chamber is headspaced on the short side. Not too short, but less clearance than on a standard rifle, and the throat isnt as roomy either.

But are all the DCM chambers like this or just a few? Anybody else have a DCM rifle here?
Link Posted: 1/6/2006 6:19:16 AM EDT
Barrels with the Wylde 223 chamber do not suffer any of those problems. I have had two Wylde chambered Wilson NM barrels and they both have eaten anything and everything I have fed them.

Who made your barrel and what chamber reamer did they use (223 SAAMI, 5.56 NATO, Wylde, CLE, something else)?
Link Posted: 1/6/2006 7:04:59 AM EDT
Aren't DCM barrels supposed to be "accuacy" barrels? That usually means they have exceptionally tight specs, and sometimes even slightly undersized chambers or very short throats. I'd have the barrel checked out by a 'smith that understands accuracy shooters and their needs. You may need to have the chamber and throat reamed or polished a bit to open them up for more common ammunition. Remember, high power competitors often hand make (not just handload) every single round, with sometimes excessive attention to the minutest detail and dimension. They're used to having specific cases that only work in specific rifles, and to using one set of dies for rifle #1 and a different set in the same caliber for rifle #2 because that gets them tighter groups with both.
Link Posted: 1/6/2006 9:58:29 AM EDT

Originally Posted By GHPorter:
Aren't DCM barrels supposed to be "accuacy" barrels? That usually means they have exceptionally tight specs, and sometimes even slightly undersized chambers or very short throats.



"DCM" (National Match is the correct term) barrels ARE accuracy barrels. What they are NOT is BENCHREST barrels.

The minimum dimension, tight neck chambers of which you speak are used by serious benchresters (who do ultra-anal brass prep) and by goobers who do not understand the various precision shooting disciplines and want to call their barrel a "match" barrel.

A typical NRA Highpower match requires the rifle to cycle perfectly through 88 rounds of ammunition, 40 of which are in rapid fire. Chambers used by quality gunsmiths and riflemakers in barrels destined for the National Match ARs are anything but benchrest/"match" tight.

The Wylde chamber (designed by veteran HP shooter/riflebuilder Bill Wylde) is essenatially a 5.56 NATO chamber with a neck shorter than NATO specs but longer than SAAMI specs.

Without knowing what chamber reamer was used in this particular "DCM" barrel, offering a suggestion on what could be wrong is nearmy impossible.
Link Posted: 1/6/2006 11:24:35 AM EDT
The barrel was made by DPMS, which BTW Ive also heard is notorious for tight chambers. According to DPMS it is a 5.56 NATO chamber.
Link Posted: 1/6/2006 12:03:06 PM EDT

Originally Posted By jaymeister99:
The barrel was made by DPMS, which BTW Ive also heard is notorious for tight chambers. According to DPMS it is a 5.56 NATO chamber.


I suggest finding a competent gunsmith with access to the chamber dimensions for 5.56 NATO. Have him do a chamber cast, mic the cast and compare to chamber print for dimensional correctness.

A correctly machined 5.56 NATO chamber should spit everything you feed it, if the rest of the rifle is working correctly.
Link Posted: 1/6/2006 6:01:21 PM EDT

Originally Posted By SWO_daddy:

Originally Posted By jaymeister99:
The barrel was made by DPMS, which BTW Ive also heard is notorious for tight chambers. According to DPMS it is a 5.56 NATO chamber.


I suggest finding a competent gunsmith with access to the chamber dimensions for 5.56 NATO. Have him do a chamber cast, mic the cast and compare to chamber print for dimensional correctness.

A correctly machined 5.56 NATO chamber should spit everything you feed it, if the rest of the rifle is working correctly.



Can most good gunsmiths do this or do I need to go to a guru? Any idea on the costs for this?
Link Posted: 1/6/2006 6:43:49 PM EDT

Originally Posted By jaymeister99:

Originally Posted By SWO_daddy:

Originally Posted By jaymeister99:
The barrel was made by DPMS, which BTW Ive also heard is notorious for tight chambers. According to DPMS it is a 5.56 NATO chamber.


I suggest finding a competent gunsmith with access to the chamber dimensions for 5.56 NATO. Have him do a chamber cast, mic the cast and compare to chamber print for dimensional correctness.

A correctly machined 5.56 NATO chamber should spit everything you feed it, if the rest of the rifle is working correctly.



Can most good gunsmiths do this or do I need to go to a guru? Any idea on the costs for this?


Any gunsmith worth his name should know how to make a chamber cast and should be able to find a copy of the 5.56 NATO chamber dimensions.

Cost? I've never had it done, but I can't imagine it being much more than $50. Small price to pay for peace of mind.
Link Posted: 1/6/2006 8:31:04 PM EDT

Originally Posted By SWO_daddy:

Originally Posted By jaymeister99:

Originally Posted By SWO_daddy:

Originally Posted By jaymeister99:
The barrel was made by DPMS, which BTW Ive also heard is notorious for tight chambers. According to DPMS it is a 5.56 NATO chamber.


I suggest finding a competent gunsmith with access to the chamber dimensions for 5.56 NATO. Have him do a chamber cast, mic the cast and compare to chamber print for dimensional correctness.

A correctly machined 5.56 NATO chamber should spit everything you feed it, if the rest of the rifle is working correctly.



Can most good gunsmiths do this or do I need to go to a guru? Any idea on the costs for this?


Any gunsmith worth his name should know how to make a chamber cast and should be able to find a copy of the 5.56 NATO chamber dimensions.

Cost? I've never had it done, but I can't imagine it being much more than $50. Small price to pay for peace of mind.



Thanks for all the help. Can they usually do the reaming too? Again (sorry) any idea on cost to ream it out to expand the dimensions?
Link Posted: 1/7/2006 11:16:24 AM EDT
Hopw handy are you? If it were my barrel I would just buy a Wylde finishing reamer and touch up the chamber. I understand some folk might be nervous about doing that though.
Link Posted: 1/7/2006 11:21:21 AM EDT

Originally Posted By jaymeister99:

Originally Posted By SWO_daddy:

Originally Posted By jaymeister99:

Originally Posted By SWO_daddy:

Originally Posted By jaymeister99:
The barrel was made by DPMS, which BTW Ive also heard is notorious for tight chambers. According to DPMS it is a 5.56 NATO chamber.


I suggest finding a competent gunsmith with access to the chamber dimensions for 5.56 NATO. Have him do a chamber cast, mic the cast and compare to chamber print for dimensional correctness.

A correctly machined 5.56 NATO chamber should spit everything you feed it, if the rest of the rifle is working correctly.



Can most good gunsmiths do this or do I need to go to a guru? Any idea on the costs for this?


Any gunsmith worth his name should know how to make a chamber cast and should be able to find a copy of the 5.56 NATO chamber dimensions.

Cost? I've never had it done, but I can't imagine it being much more than $50. Small price to pay for peace of mind.



Thanks for all the help. Can they usually do the reaming too? Again (sorry) any idea on cost to ream it out to expand the dimensions?


Yep, a good gunsmith can ream your rifle's chamber to something a bit looser. Cost will depend on whether or not he already has the reamer on hand.
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