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Posted: 1/4/2006 2:41:21 PM EDT
I just built another rifle. Its a brand new CMT limited edtion upper, with M4 Feedramps, 14.5" chrome-lined barrel, 1/7 twist. I used a RRA lower and a CMT LPK. My problem is it won't feed Wolf Ammo. I know its just Wolf and all but im still curious and I would like it to work. It works fine with every other type of ammo I put though it S&B, Remington, XM855PD and Q3131. The problem occurred with Wolf 55 gr. FMJ, polymer coated new ammo, about 40 degrees F. The same Wolf functioned perfectly in my Bushmaster and J&T build.

It will load when I hit the bolt-release, but when I fire the rifle, it extracts properly but does not feed another round, the bolt just closes. I pulled the charging handle back and let go, it fed another round but didn't feed upon firing it. Sometimes it just doesn't feed and the bolt will close, sometimes it will jam. The rifle was very clean when the problem occurred. I used brand new USGI mags that I know work.

I know its not the bolt/carrier becuase I put my Bushy b/c in the rifle to see and it still malfunctioned. Could it be the M4 ramps? That is the only thing that my CMT upper has that my other two rifles don't.

What do you guys think is the problem? Sorry I wrote so much I tried to describe the problem as best I could.

Thanks,

Nic
Link Posted: 1/4/2006 4:10:38 PM EDT
put one round in the mag.
fire weapon
if bolt is not held open you have a gas problem. Check Gas port, Gas key on carrier.

If bolt is help open it "may" be that you have weak mag springs.

beyond that I don't know. Tweak may have a answer
Link Posted: 1/4/2006 4:38:00 PM EDT
Link Posted: 1/4/2006 5:34:39 PM EDT
I just saw the checklist not before I went to shoot the rifle though. I don't think its a gas problem cause it only does it with Wolf ammo, and I don't think its a mag problem cause they are new mags that work fine in my other rifles with wolf. I'll try the one round in the mag the next time I go shooting though.

Nic
Link Posted: 1/4/2006 6:50:56 PM EDT
Sure does sound like short stroking caused by Wolfs weak powder charge... Definitely do the single feed, empty mag test to see... You could very well have a gas leak, possibly caused by the carrier key or gas block...
Link Posted: 1/5/2006 7:35:25 AM EDT
I'm working on the same issue with my 16" bushy. When you do your shortstroke test, make sure that if you see it locking back that it is not catching on the bolt carrier instead of where it is supposed to..(bolt face.) Mine holds on the carrier consistently. I have yet to check mine for function after changing out the buffer and spring with the new one that came with my VLTOR.
Link Posted: 1/8/2006 2:30:20 PM EDT
I just shot it again today. I noticed that two of the gas rings were lined up, and the buttstock was a little loose. I fixed those problems and it shot much better. But still not perfect. It will fail to feed on the first couple rounds, the bolt will close without feeding another round. Sometimes it will get stuck on a round that it started to feed. I did the short stroke test and it passed, the bolt locked back after firing one round, except for one mag that it just doesn't like or something.
Link Posted: 1/8/2006 2:45:57 PM EDT
[Last Edit: 1/8/2006 2:46:23 PM EDT by Triple_D]

Originally Posted By Nic4433:
Its a brand new CMT limited edtion upper, with M4 Feedramps, 14.5" chrome-lined barrel, 1/7 twist.

Could it be the M4 ramps?




Does the barrel extension have M4 cuts also, or is it only the upper that has them?
Link Posted: 1/8/2006 5:49:40 PM EDT
The upper and the extension have the M4 cuts, here is a pic

I was just wondering if anyone had problems with wolf in a rifle with M4 cuts.
Link Posted: 1/8/2006 9:18:48 PM EDT
Chamber conditions, upper bearing surface roughness, and the amount of gas actual making it back to the gas chamber during pressurization all will play a role if the rifle will cycle case coated ammo or not.

Best to just break the rifle in use brass cased ammo, and then see if the poly coated ammo will function in the rifle at a latter date.
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