Short Stroking with the can in place. Any help appreciated

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nhgunnut
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Short Stroking with the can in place. Any help appreciated

Post by nhgunnut »

First let me say I am a rookie in this area and thank you in advance for anyone sharing their experience with me.
My upper using 16" CMMG barrel is short stroking with with the a YHM Phantom in place .
The gas system is Carbine length, the load is the Remington 220 grain
The components are as follows.
CMMG 16 inch Barrel w/Carbine length gas system. (gun show grab)
YHM M4 upper (new)
YHM Gas Block/filp sight (re-purposed)
YHM BCM + Bolt (new and appears properly staked)
YHM 7.62 QD Pantom Suppressor
Oly Multi Cal Lower (new)
DPMS LPK (new)
Military Buffer tube
Buffer (used 3 throughout the testing)
After initial assembly ran the gun on three different lower assemblies
First it would eject but not load the next round. After lightening the buffer by one weight and adjusting the gas block it will for the most part load and fire the next round. but still will not lock the bolt back.
My purpose fort his rifle is to run primarily suppressed ( I have a YHM 7.62x39 carbine that runs like a top, so supersonic is a niche I have filled)
Options I am considering after reading other thread and would appreciate your thoughts on
Bob/lighten a spare hammer
Reduced power Spring set (300 fireball kit form Model 1 jumps to mind)
Last before trying a different barrel, cap the existing gas port, then turn the barrel to except a clamp on Micro Gas block at point midway between pistol and carbine length.
nhgunnut
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Joined: Sat Feb 25, 2012 7:18 am

SOLVED SOLVED

Post by nhgunnut »

Ok thanks folks for taking the time to read this.I am Embarrassed by how easy a fix it was/ I was down at a local fun shop When Andrew the rep from Samson walked in. I discussed it with him took it out of the truck, he looked it over. Grabbed a wrench adjusted the alignment on the gas block again, went out back and tested it and it ran like a top.
Like I said at the top of my post, I am a rookie and I made a rookie mistake.
TuscoTodd
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Re: Short Stroking with the can in place. Any help appreciat

Post by TuscoTodd »

Always nice when it is an easy/inexpensive fix!
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TuscoTodd
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Downrange
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Re: Short Stroking with the can in place. Any help appreciat

Post by Downrange »

I've got the same exact problem of FTF, short stroking, with subsonic rounds only in my new CMMG. Can you elaborate on the "adjustments" made, how done, etc?
I wasn't aware this had different gas settings, etc.

Seems a shame in a new upper made for 300 blk to have these issues.
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nhgunnut
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Joined: Sat Feb 25, 2012 7:18 am

Re: Short Stroking with the can in place. Any help appreciat

Post by nhgunnut »

Downrange wrote:I've got the same exact problem of FTF, short stroking, with subsonic rounds only in my new CMMG. Can you elaborate on the "adjustments" made, how done, etc?
I wasn't aware this had different gas settings, etc.

Seems a shame in a new upper made for 300 blk to have these issues.
In My Case the Yankee Hill Gas Block was slightly out of alignment and it required loosening the gas block and tapping is slightly foraward/
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Downrange
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Re: Short Stroking with the can in place. Any help appreciat

Post by Downrange »

Thanks, I'm not sure this applies to the CMMG M-4 styled upper (has the standard M-4 gas arrangement, not a flat=top or compact model. It's either on there right or not, not adjustable, at least that's what CMMG said when I called today.
I'm trying a heavier buffer, that and see if the action "shoots in" a bit...

Edit: FWIW, the 220 gr PNW sub stuff cycles just fine - a bit hotter load perhaps?

The CMMG rep says the Remmie 220 stuff doesn 't function in many actions - something about the powder burn rate maybe.
The world is made up of two kinds of people: the kind who believe that everything not specifically prohibited is legal, and those who are always looking for more things to prohibit.
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Legionaire
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Location: Hamilton, MT.

Re: Short Stroking with the can in place. Any help appreciat

Post by Legionaire »

Is youre fsb pinned or attached with set screws? If it has set screws then you loosen them and move the fsb to correct alignment and re tighten.
nhgunnut
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Re: Short Stroking with the can in place. Any help appreciat

Post by nhgunnut »

Legionaire wrote:Is youre fsb pinned or attached with set screws? If it has set screws then you loosen them and move the fsb to correct alignment and re tighten.
I resolved this problem with a new barrel
Legionaire
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Location: Hamilton, MT.

Re: Short Stroking with the can in place. Any help appreciat

Post by Legionaire »

What barrel did you replace it with? Did you ever find out if the problem was gas port size or misalignment?
nhgunnut
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Re: Short Stroking with the can in place. Any help appreciat

Post by nhgunnut »

Legionaire wrote:What barrel did you replace it with? Did you ever find out if the problem was gas port size or misalignment?
The issue with the CMMG barrel was the misalignment of the Yankee Hill machine gasblock once it was aligned properly it would run subs witht he can in place. Since I built the rifle with the goal of it being primarily a suppressed rifle . I chose to replace the barrel with a GRT stainless 16inch with a pistol length gas system. The local guy that bought the CMMG barrel from me loves it
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