Suggestions for mis-feeding CMMG MKG 45acp?

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  • Karl-just-Karl

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    I went into my photo archive and found this picture. I circled the weird notch on the back of the extractor.

    Does this misfeed look familiar?
    MKG Cartridge Misfeed2.jpg
     

    JP Gringo

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    Pretty much identical looking misfeeds.... I am pondering taking apart the MKG and taking down the burr below the feed ramp. I saved the last three rounds that were the misfeed rounds. All had fresh scrape marks along the nose of the round and into the casing. I am just baffled by the order of the misfeeds. Expected it to be a random event but there appears to be a pattern of sorts. 2nd or 10th round in mags one and two. Will let y'all know what happens next once I decide where to go with this.
     

    Karl-just-Karl

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    Pretty much identical looking misfeeds.... I am pondering taking apart the MKG and taking down the burr below the feed ramp. I saved the last three rounds that were the misfeed rounds. All had fresh scrape marks along the nose of the round and into the casing. I am just baffled by the order of the misfeeds. Expected it to be a random event but there appears to be a pattern of sorts. 2nd or 10th round in mags one and two. Will let y'all know what happens next once I decide where to go with this.
    Mine is always third to the last round in the magazine. Nowhere else. My guess is that it is a timing of physics in a tolerance stack-up that is impossible to predict and characteristic to each individual firearm.

    Buffer weight and spring should be consistent. Cartridge weight should be consistent. Magazine spring tension is the only thing that should change shot to shot except for the overall firearm weight.

    I messed around with heavier/lighter charges in my loads. It didn't seem to make much difference.

    I won't ever depend on this firearm to protect my life and I wouldn't sell it without full disclosure of it's history, but I am glad that the beveling of the barrel extension allows me to enjoy some steel-slamming at the range with this oddity of the universe. Who would have thought CMMG might not be perfect? Not CMMG!
     

    SSE

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    I have a Wolfpack Armory AR45 that was giving me some strange feeding problems. I was thinking springs, buffers, ect. but cleaning up the feed ramp seemed to help it a little. So I did it again and it got a little better. After the third time on the lathe with a file and polishing ,it is running very well.
    It looked very good to start with but thats what it needed.
     

    JP Gringo

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    Jul 3, 2022
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    Ok, new up date and its looking good. Under the current set up, zero feeding failures after approximately 115 rounds through the three Glock 21 mags and the one SGM 24 rd mag. My current set up is I took all the weights out of the buffer to increase the bolt speed.

    I purchased the CMMG tuning kit and was playing around with that for 50 or 60 rounds. As the weights increased the nose up misfeed increased, so I began going opposite and removed the tuning weights. Back to square one. Of the three Glock 21 mags, One mag would run flawless the other two nose up misdeeds on the 11th rd, consistently. The only other place to lose weight was in the buffer. SO I took out the buffer and removed the internal weights. The OEM buffer that came in my MKG weighed 3.3 oz. Running empty, not sure yet what the buffer alone weighs since I don’t have my scale with me…. But that appears to have done the trick. Since removing the buffer weights I have had NO nose up misfeeds or any other issues with the weapon. I will update in another day or two once I resupply on the ammo.
     

    Karl-just-Karl

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    Ok, new up date and its looking good. Under the current set up, zero feeding failures after approximately 115 rounds through the three Glock 21 mags and the one SGM 24 rd mag. My current set up is I took all the weights out of the buffer to increase the bolt speed.

    I purchased the CMMG tuning kit and was playing around with that for 50 or 60 rounds. As the weights increased the nose up misfeed increased, so I began going opposite and removed the tuning weights. Back to square one. Of the three Glock 21 mags, One mag would run flawless the other two nose up misdeeds on the 11th rd, consistently. The only other place to lose weight was in the buffer. SO I took out the buffer and removed the internal weights. The OEM buffer that came in my MKG weighed 3.3 oz. Running empty, not sure yet what the buffer alone weighs since I don’t have my scale with me…. But that appears to have done the trick. Since removing the buffer weights I have had NO nose up misfeeds or any other issues with the weapon. I will update in another day or two once I resupply on the ammo.
    Very interesting. Looking forward to your update!
     

    A63buggy

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    Jul 27, 2022
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    Jumping in to add my build and issue. CMMG Radial Delayed. I am not getting the nose high feeding jam as you are experiencing but a fails to go into fully into battery. It appears that after contacting round and begins to chamber round the force begins to shove bolt face back just slightly beginning bolts rotation enough the bolts lugs jam into face of chamber extension. When you give slight rearward pull to unweight bolt and carrier group you can see lugs pop into place. With just pressure released you can let bolt go and goes into full battery easily.

    I am running the 16" barrel with 45acp radial delayed bolt and carrier group as delivered stock with no tuning weights in carrier group. Started with stock ar15 carbine spring and buffer. At this buffer weight with and with out empty magazine releasing bolt lets it ride fully home. No issues with lrbho catching.

    Dummy rounds and live rounds cause the same slight rotation of bolt face.

    I did try H2 and H3 buffers same result. Pulled out my 9mm blow backs 7.7oz. Buffer and tried it with dummy rounds. Thats seems to get bolt into the barrel extensions lugs before rotating and goes into full battery. Won't fire that with live rounds the 7.7oz buffer is longer than standard AR buffers. Buffer bottoms out before you can get bolt back far enough to lock bolt to rear.

    I'm waiting for a tunable ar buffer and the bolt carrier weights to add up to 7.7 and go to the range.

    Will pictures pics after I see mt first ever long winded write up posts!
     

    JP Gringo

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    Jul 3, 2022
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    Update on my MkG… It’s better. So I began yesterdays session with a cleaned weapon and 300 rounds of 230 gr, FMJ. Buffer had no weights in it and buffer spring is OEM. Through the first 260 rds only Mag2 had nose up misfeeds regardless of order fired. Misfeed was always on 11th rnd. When mis feed occured I would load 2 more rds for a total of 5 rds in mag and finish the cycle. Mag2 would finish cycle with out misfeed. So I figure that Mag2 will be removed from use after this evolution. Then came the last cycle with all three Mags. All had nose up mis feeds on 11th rnd and I was finished with my 300 rds.

    The last cycle I am going to attribute to dirty weapon with some reservations. It was only 300 rnds fired from a clean MkG. The ammo used was a mix 200 Sellier&Bellot and 100 Blazer. The Blazer ammo had some soot like residue that was on my bench and pant leg. I used the Blazer in the last 100 rds.

    So Iam leaning towards the Blazer ammo as part of the issue with the odd soot residue on my bench. The soot was a black, flakey material that came out of the ejection port when casing was ejected.

    My other “issue” is that after 260 rnds all mags had mis feeds. If this is a thing with this CMMG MkG, then it is the only weapon I have that needs a cleaning after every 260 rnds fired.

    I will be scratching my head another week and still no response from CMMG.

    So in another week or so after I run the experience through the gray matter and some after action analysis I will try again with a clean weapon and single brand of ammo.
     

    Karl-just-Karl

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    Update on my MkG… It’s better. So I began yesterdays session with a cleaned weapon and 300 rounds of 230 gr, FMJ. Buffer had no weights in it and buffer spring is OEM. Through the first 260 rds only Mag2 had nose up misfeeds regardless of order fired. Misfeed was always on 11th rnd. When mis feed occured I would load 2 more rds for a total of 5 rds in mag and finish the cycle. Mag2 would finish cycle with out misfeed. So I figure that Mag2 will be removed from use after this evolution. Then came the last cycle with all three Mags. All had nose up mis feeds on 11th rnd and I was finished with my 300 rds.

    The last cycle I am going to attribute to dirty weapon with some reservations. It was only 300 rnds fired from a clean MkG. The ammo used was a mix 200 Sellier&Bellot and 100 Blazer. The Blazer ammo had some soot like residue that was on my bench and pant leg. I used the Blazer in the last 100 rds.

    So Iam leaning towards the Blazer ammo as part of the issue with the odd soot residue on my bench. The soot was a black, flakey material that came out of the ejection port when casing was ejected.

    My other “issue” is that after 260 rnds all mags had mis feeds. If this is a thing with this CMMG MkG, then it is the only weapon I have that needs a cleaning after every 260 rnds fired.

    I will be scratching my head another week and still no response from CMMG.

    So in another week or so after I run the experience through the gray matter and some after action analysis I will try again with a clean weapon and single brand of ammo.
    I've been down that road too. I was cleaning after every test session even if it was only 100 rounds. I was cleaning the magazines too. I even tried lubricating the internals of the mags with graphite.

    Since the rework of the barrel extension my misfeeds have dropped dramatically. They have been non-existent with factory ammo, but I have only put a few hundred down range since the mod. My MKG became a project gun so it isn't at the forefront of choices when I get range time.

    When you finally get fed up and disgusted with the thing, get out the Dremel.
     

    JP Gringo

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    So, here is what I have decided to do for next step now that CMMG is radio silent on the two emails and one phone call.... I am going to swap out the short 6" buffer tube and install a standard carbine buffer tube and guts. I picked up a standard length RipStock Brace with 7" buffer tube. The new carbine length buffer weighs 3.0 oz. I have no idea what to expect other than the continued nose up misfeeds..... but you never know..... might get lucky. Figure the extra inch may some how change something in the timing or the spring force on the bolt. Will update y'all in a couple of days.

    Jack P.
     

    JP Gringo

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    SIZE DOES MATTER.... Good news with swapping out the OEM RipBrace for the CMMG Standard Length Carbine RipBrace. For my MkG, this went well, really well!!! Short story is that I shot approximately 360 rounds and used two different buffer springs and buffers. The buffer spring and buffer that came with the new CMMG RipBrace pretty much ran flawless through all five, Glock 21, 13rd magazines. I say pretty much since the last evolutions 5 and 6, no misfeeds but the bolt did not lock back after last round. I can live with that.

    I shot the MkG through six evolutions. Five evolutions(1-5) with all five magazines and one evolution (evolution 6) with Magazines 1(13 rounds) and 2 (7 rounds), ran out of ammo.

    The Geissele Super42 wire buffer spring and H1buffer had nose up misfeeds in all three evolutions 2,3, and4, with my Magazines 1 and 2 on the 11th round. The Geissele Super42 wire buffer spring and H1buffer were used in evolutions 2,3, and 4. Geissele buffer weighs 3.7 ounces.

    The CMMG standard carbine buffer spring and buffer were used in evolution 1,5, and 6. CMMG buffer weighs 3.0 ounces. Again, there were no mis feeds with this setup.

    The buffer tube that came with the CMMG RipBrace is 7" deep, 1" longer than the RipBrace that originally came with the MkG from the factory.

    So for my MkG, today, the fix appears to be the Standard length CMMG Carbine RipBrace with standard length buffer spring and 3.0 oz. buffer.

    Will try this set up again in a couple of weeks when I can get back to the range and do some more plinking.

    May consider making the Geissele buffer lighter to 3.0 oz and see if that fixes the nose up misfeeds. But that will be after I am satisfied with this new RipBrace and buffer system.


    Well, I hope this helps. Happy Shooting....

    Jack P.
     

    A63buggy

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    Jul 27, 2022
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    Gringo, Karl,

    when did you guys receive your CMMG 45 barrel and bolts?

    I only just recently received mine after a long period of no one having them in stock. Perhaps they tweaked something when they made the recent production run. After next weeks range day I’ll be tearing it down for some cosmetic things and handguard swapping. I’ll have barrel off to take clear pictures of ramp to try and compare with what Karl dremmeled.

    side note thought I’d looked thru those other boards for similar threads. Off to look again. Also same problem. Totally ignored by CMMG non existent customer service. Not a peep.

    Rick
     

    Karl-just-Karl

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    Gringo, Karl,

    when did you guys receive your CMMG 45 barrel and bolts?

    I only just recently received mine after a long period of no one having them in stock. Perhaps they tweaked something when they made the recent production run. After next weeks range day I’ll be tearing it down for some cosmetic things and handguard swapping. I’ll have barrel off to take clear pictures of ramp to try and compare with what Karl dremmeled.

    side note thought I’d looked thru those other boards for similar threads. Off to look again. Also same problem. Totally ignored by CMMG non existent customer service. Not a peep.

    Rick
    My CMMG was originally marketed as a "Guard". At some point it was also an MKG. The Banshee name came later. I originally purchased mine as a complete firearm in mid to late 2018 if I remember correctly.

    It had problems and disappointed from the outset.

    As far as the Dremeling...all I tried to do was round over the edge from the flat part of the barrel extension to the feed ramp. I didn't attempt to recontour or re-angle the feed ramp or anything else. The barrel extension is pretty hard and I used a grinding stone at medium low speed. It still slipped a couple times and it ran away from me. I finished the modification by polishing the new radiused edge with some rubberized abrasives.

    With normal eyes and lighting it looks pretty good. With direct sunlight and magnification it looks like I finished a case of beer before getting started.

    I have to be pretty disappointed with a firearm to get out the Dremel.
     

    Karl-just-Karl

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    For CMMG, this thread is over 10K views now. Lots of folks must need some suggestions for their misfeeding MKG45s.

    Now you're not answering your phones or e-mails?

    That's sad.
     

    JP Gringo

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    Gringo, Karl,

    when did you guys receive your CMMG 45 barrel and bolts?

    I only just recently received mine after a long period of no one having them in stock. Perhaps they tweaked something when they made the recent production run. After next weeks range day I’ll be tearing it down for some cosmetic things and handguard swapping. I’ll have barrel off to take clear pictures of ramp to try and compare with what Karl dremmeled.

    side note thought I’d looked thru those other boards for similar threads. Off to look again. Also same problem. Totally ignored by CMMG non existent customer service. Not a peep.

    Rick
    I thought I posted a reply last week.... ok

    I put in my order in Dec of 2020 and received the MkG in late Aug 2021. It was listed as a Pistol, Banshee™ 300, MkG, 45 ACP. It has a 5 inch barrel.

    Jack P.
     

    JP Gringo

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    Another update:

    For me, replacing the original RipBrace (6") with a carbine length RipBrace(7") appears to be the fix.

    This weekend I fired 390 rounds, 230 grain FMJ through the MkG. PMC Bronze was the ammo used.

    Only used the five Glock 21 mags.

    RipBrace buffer weighed 2.5 oz. Original weight was 3.0 oz.

    Geissele42 buffer weighed 3.0 oz. Original weight was 3.7 oz.

    Only feeding issues or issues of any kind was with my number 2 Glock 21 mag. Nose up misfeed, 11th round. Rounds 12 and 13 cycled with out misfeed. The misfeeds occurred in 4 out of the 6 evolutions completed.

    Glock 21 mags 1,3,4,5 all performed with no misfeeds or cycling issues. All mags locked back on last round through entire session.

    My fix appears to be to use a standard length carbine buffer tube and buffer weight should be 3.0 oz. or lighter.
    I plan on using the 2.5 oz buffer and buffer spring that came with the 7" Ripbrace.
    I plan on holding the Geissele42 as a backup for now.
    I plan on removing my number 2 mag out of rotation. Maybe swap out or replace the mag spring to see if that fixes Mag 2.

    Well, that about does it for this session. Fingers crossed that this is the "fix". Will keep y'all updated how future sessions go.

    Jack P.

    I wonder if CMMG at a minimum would reimburse me for the ammo used to find this "fix" since they have been radio silent and email silent through this whole process? Pipe dream right.....
     
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    Karl-just-Karl

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    I wonder if CMMG at a minimum would reimburse me for the ammo used to find this "fix" since they have been radio silent and email silent through this whole process? Pipe dream right.....
    I asked them a similar question since I was doing a lot of troubleshooting for them. The answer was "No".

    Glad to read you got something working for you.

    I'm just really soured on CMMG because they refuse to acknowledge that every now and then they produce a lemon.
     

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