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(First post) Ejection problems on MK-3


CaveMan

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They come with an o-ring on the extractor spring.  I tried mine both ways (at the factory's suggestion) I don't think it is an extractor issue.  The spring is strong and it is getting a good bite.  There is no sign on the rim of the extractor pulling off.  They are finally admitting they drilled too big a hole for the gas port.  With the A2 stock, buffer and spring there are no stovepipes but all the brass still ejects to 1:30.  When I manually eject a loaded round it pops right out at 5:00 like it is supposed to.  (Different forces acting on it I know.)  Evidently the size and location of the gas port worked fine on their 16" barrels but when the extra 2 inches is added there is just too much gas for the system.

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I agree , heavy buffer , I like the Superior (Tubbs ) spring , but a adj. gas block my be the thing , if what they say is true about the port size .

With an adj . gas block , you could go back to a collapsible stock .

I would not worry too much where the brass is landing , as long as it gets out of the way & it may change when the round count goes up .

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The reason that where the brass matters is that it's trajectory is caused by it hitting the inside of the ejection port on the way out.  That was what was initially causing all the stovepipes.  The heavier buffer and spring has slowed it up just enough to get the brass out but the fact that it is still hitting makes me think that eventually I'll get stovepipes again, probably at the worst possible moment.  The working of the action is so violent that I'm afraid the rifle is just going tear itself up.  (One of the other posters had his bolt stop break in two.)  I'm going to try to take some high speed video of it to observe what is happening in slow motion.

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Sounds to me like Brent and Co. up there in Mo. are 'Franken-gunning it' like there's no tomorrow. They sent me a UPS return label and I thought 'No thanks.' This will be a never-ending friggin' saga.

I started my own thread today detailing the EXACT same problems as you. I sold it off and bought a DPMS. I figured, stick with the company that has the most experience with the SR25 'pattern' rifle;  DPMS

I .. am ....a ... happy camper.  <thumbsup>

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  • 2 weeks later...

I would never do that to a customer.

Exactly - makes no sense.  If it functions - now - in rifle-stock config, then it should have functioned fine in collapsible-stock config.  If it DOES function now, way better than the way it was, then the parts they ship for the collapsible-stock config are radically **wrong**    <<<  I have much better words for it than that... 

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They finally admitted the gas port was too big for an 18 inch barrel.  They told me they didn't have any barrels so they were putting the A2 stock on.  (Heavier buffer without paying the price of an H3 buffer.)  The rifle ejects everything to 1:00 so the brass is obviously still hitting something on the way out.  They are using band-aids instead of fixing the problem.  Just because I am in so deep now and I still like the way the rifle looks and feels I've ordered an adjustable gas block.  (That was the first advice we got about these rifles but I was hoping the fix would come at CMMG's expense rather than mine.)  I'll report back on the results.

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A quick-fix for this thing, permanently, would be a barrel replacement from someone that's making 18"-ish barrels...  I'd suggest Fulton Armory, without hesitation.  If you buy the barrel from them, I'd do your barrel install for free, if you shipped me the upper.  <thumbsup>

****  Disclaimer - I'm not a business, and don't make money from firearms...  just someone that wants to see it "right."  I wouldn't even think about receiving money for something like this. 

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You would not believe how violent the action is when this rifle goes off.  It feels like it is literally trying to shoot itself apart.  (I think it may have already done in the cheap scope I was using to experiment.)  My AR's go all the way to 450 Bushmaster and they all run smooth as butter.  My bolt guns go all the way to .458 Winchester Mag. so recoil alone isn't what I am feeling.  If the adj. gas block can't tame it down then it goes back to CMMG for good.  Thanks for the install offer 98; I thought about telling the factory to send me a barrel with the proper gas port when they get some in.  I don't have AR 308 specific tools yet but since I like to tinker I'll probably get them to go along with my AR-15 tools.

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It seems to be working better now. I only had time to put about 9 rounds through it yesterday, but it's working pretty good. It ejects to between 1 and 2 o'clock position now.

It seems a lot less "handy" though. I never weighed it with carbine buffer tube and six-position stock, but now it seems almost a pound heavier with A2 stock. I was hoping for a quick and light field rifle in .308 (which may be a pipe dream), but now it seems like it's more of a designated marksman rifle.

Eh. At least it's working!

3xt4al.jpg

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If the gas port on the bbl. is too big , you will definitely have more of a violent action response . The adj. gas block should be able to address that .

I would not worry about what the brass is hitting as long as it gets out of the way of the next round to be fed or on what the brass is doing or what it may be hitting on the way out .

This rifle needs a higher round count before you start diagnosing for some thing that may or may not be a problem . With the adj. gas block , you will be able to tune the rifle to the ammo or a range of ammo types ,or for a collapsible stock configuration .

I don't think I have ever  weighed the difference between the two stock configurations , any one know ?

Now this is what I would do & its just me , that I'm talking about , I would get another barrel , install it , send them there's back , for a refund for the price of the barrel . They did say the screwed up & if you have it in writing ( or not ), well , they have little to say because they admitted they screwed up .

Money back ( no matter what they give up )would go toward the price of any barrel you get & you will probably have a better barrel ,too boot . The adj. gas block will help also , maybe with less fuss & $$$$.

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The obvious answer was the adjustable gas block; I was just hoping to get the problem solved on CMMG's nickel rather than mine.  Being that I am rather stubborn and since I really do like the rifle I went ahead with a PRI block.  3 and 1/4 turns out and all the brass from 5 different loads ejects briskly and lands in a pile about 6 feet away at 4 o'clock.  (I'll disagree about what the brass is doing not being important; it's a symptom of a problem.  Kind of like having a good pulse and heart rate so don't worry about the persistent cough.)  The recoil impulse seems to be softer as well.  Early on I had put a 50 round dose of Tubbs Final Finish through the barrel and even while I was half watching with one eye to see if it was going to stovepipe I got a few 1 inch groups with Federal Gold Medal Match so I think the barrel has real potential for accuracy.  Now to start playing with all these boxes of long skinny bullets to see what my old eyes can do with the best handloads.  I'll keep reporting and also see what CMMG has to say about my expenses.

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Just ordered a JP Cooley compensator.  Even though it is just a 308 the comp should take enough of the recoil out to make it possible to keep the scope on target between shots.  The A2 stock actually seems more appropriate for this rifle.  It really isn't a carbine and since I am almost 6' 5" I still added a Sims pad to it for length.  I don't particularly care for the standard carbine stocks anyway.  If I go back to a collapsible it will probably be a Magpul or and Ace.  All my rifles are set up for hunting rather than zombie control so I may just stick with the A2.

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Just ordered a JP Cooley compensator.  Even though it is just a 308 the comp should take enough of the recoil out to make it possible to keep the scope on target between shots.  The A2 stock actually seems more appropriate for this rifle.  It really isn't a carbine and since I am almost 6' 5" I still added a Sims pad to it for length.  I don't particularly care for the standard carbine stocks anyway.  If I go back to a collapsible it will probably be a Magpul or and Ace.  All my rifles are set up for hunting rather than zombie control so I may just stick with the A2.

your prolly right then...the a2 will work for ya....im just glad you got it shootin!  I promise you this....the more lead you get down the pipe the better she will work <thumbsup> Wash

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