Posted: 12/23/2011 3:04:03 PM EDT
|
Finally had some time today to go shoot my new M4 .22LR for the first time since getting it a couple of months ago, and have to say it was the most fun I've ever had shooting .22LR. I've had a few conversions before, both for my 1911s and ARs, but the reliability was so terrible with all of them that it took all the fun out of using them and really turned me off from any rimfire guns. Since the new range I shoot at most often doesn't allow centerfire rifle rounds, I decided to give the .22LR another shot, and so far I'm glad I did. However, it wasn't without some problems, which unfortunately I almost expected to have. I fired around 800 rounds through it today, and while I didn't have any failures to feed or eject (aside from what appears to be a bad magazine), I did have a very high number of misfires due to light strikes. I'd say I had about 15%-20% failure rate, but it was very inconsistent, meaning sometimes I could get through the entire magazine without a single misfire, but on the next magazine I could have 3 back to back, or have half of the magazine misfire at random. I don't think it was the ammo issue, either, because it was consistently happening to all 3 brands I had with me today - CCI Mini Mags, Federal bulk and Winchester bulk (from WalMart value packs). I picked up and inspected many of those rounds, and they all seem to have a fairly decent indentation on the rim, so I know they were struck by the firing pin, but I guess not hard enough. Do I need a heavier hammer spring, or lighter firing pin spring? I was running it on RRA lower with 2-stage NM trigger (with notched hammer), if it makes any difference. Or is there anything else I could do to fix this issue (polish the firing pin maybe?).
|
|
Quoted:
Finally had some time today to go shoot my new M4 .22LR for the first time since getting it a couple of months ago, and have to say it was the most fun I've ever had shooting .22LR. I've had a few conversions before, both for my 1911s and ARs, but the reliability was so terrible with all of them that it took all the fun out of using them and really turned me off from any rimfire guns. Since the new range I shoot at most often doesn't allow centerfire rifle rounds, I decided to give the .22LR another shot, and so far I'm glad I did. However, it wasn't without some problems, which unfortunately I almost expected to have. I fired around 800 rounds through it today, and while I didn't have any failures to feed or eject (aside from what appears to be a bad magazine), I did have a very high number of misfires due to light strikes. I'd say I had about 15%-20% failure rate, but it was very inconsistent, meaning sometimes I could get through the entire magazine without a single misfire, but on the next magazine I could have 3 back to back, or have half of the magazine misfire at random. I don't think it was the ammo issue, either, because it was consistently happening to all 3 brands I had with me today - CCI Mini Mags, Federal bulk and Winchester bulk (from WalMart value packs). I picked up and inspected many of those rounds, and they all seem to have a fairly decent indentation on the rim, so I know they were struck by the firing pin, but I guess not hard enough. Do I need a heavier hammer spring, or lighter firing pin spring? I was running it on RRA lower with 2-stage NM trigger (with notched hammer), if it makes any difference. Or is there anything else I could do to fix this issue (polish the firing pin maybe?). Do you have a force gage? Measure the force of the cocked hammer where it strikes the firing pin, just where the sear breaks. Lets see which hammer spring you are running. I realize everyone doesn't have a gage, but maybe you already know if your hammer spring is the stronger one? Maybe you can just do a comparison sanity check on one of your other hammer springs to verify you are running the stronger spring? If this lower had problem setting off Russian surplus for example, you may need to change the hammer spring. |
|
Quoted:
Quoted:
Finally had some time today to go shoot my new M4 .22LR for the first time since getting it a couple of months ago, and have to say it was the most fun I've ever had shooting .22LR. I've had a few conversions before, both for my 1911s and ARs, but the reliability was so terrible with all of them that it took all the fun out of using them and really turned me off from any rimfire guns. Since the new range I shoot at most often doesn't allow centerfire rifle rounds, I decided to give the .22LR another shot, and so far I'm glad I did. However, it wasn't without some problems, which unfortunately I almost expected to have. I fired around 800 rounds through it today, and while I didn't have any failures to feed or eject (aside from what appears to be a bad magazine), I did have a very high number of misfires due to light strikes. I'd say I had about 15%-20% failure rate, but it was very inconsistent, meaning sometimes I could get through the entire magazine without a single misfire, but on the next magazine I could have 3 back to back, or have half of the magazine misfire at random. I don't think it was the ammo issue, either, because it was consistently happening to all 3 brands I had with me today - CCI Mini Mags, Federal bulk and Winchester bulk (from WalMart value packs). I picked up and inspected many of those rounds, and they all seem to have a fairly decent indentation on the rim, so I know they were struck by the firing pin, but I guess not hard enough. Do I need a heavier hammer spring, or lighter firing pin spring? I was running it on RRA lower with 2-stage NM trigger (with notched hammer), if it makes any difference. Or is there anything else I could do to fix this issue (polish the firing pin maybe?). Do you have a force gage? Measure the force of the cocked hammer where it strikes the firing pin, just where the sear breaks. Lets see which hammer spring you are running. I realize everyone doesn't have a gage, but maybe you already know if your hammer spring is the stronger one? Maybe you can just do a comparison sanity check on one of your other hammer springs to verify you are running the stronger spring? If this lower had problem setting off Russian surplus for example, you may need to change the hammer spring. Thanks for the suggestion, but unfortunately, I don't have the force gauge to measure it. It's a factory RRA lower with their 2-stage trigger, that's about all I know about it. I've never shot the Russian stuff with this lower, either, so I don't know how it would work on that. I guess I could try running this upper on my LMT lower with LMT 2-stage trigger next time I go and see if it makes any difference... |
|
Quoted:
Quoted:
Notched. Oh........might try a lower with a rounded DPMS style hammer. Do you have one you can pop in? Also, the spring on the hammer matter too. Too soft is not good. I have DPMS trigger in my 9mm SBR lower, so I guess I could take the mag block out and try it as well. But to be honest, I hate that trigger - it's heavy and gritty - so I wouldn't want a trigger like that in my .22 AR. The only reason I have it in my 9mm AR is because it required a rounded hammer to work with 9mm ramped bolt, and back when I built it several years ago, there were no 2-stage triggers available with rounded hammers. As a matter of fact, now that most manufacturers switched from notched to rounded triggers, I've been thinking about replacing that DPMS trigger with a new 2-stage trigger. |
|
Quoted:
i run a notched hammer and 4.5 lb spring and mine runs fine. i might just be lucky though. pull you your firing pin out and make sure it is not broke. mine was and it acted like you describe. I'm not sure what the firing pin should look like, but here's a couple of pictures of mine. It doesn't appear to be broken... EDIT: I also found this thread last night, and I'm seriously thinking about trying that modification and see if it helps with my issues. I may just order a spare firing pin from CMMG (if they sell them individually) and take my Dremel tool to it. Link 
|
|
The hammer spring is installed correctly.
I cleaned the gun last week and went back to the range to see if it made any difference (thinking maybe it could be attributed to "break in"), but absolutely nothing had changed and it behaved exactly the same way the second time out. The strangest part was that it was very inconsistent - I could go through the whole magazine without a single failure, reload it, and have 3 "duds" in a row on the second magazine, then fine for the rest of the magazine, reload again, and have every 5th round fail, etc. I'm building a new lower thins weekend with a Geiselle trigger and see if it works any better than my RRA notched hammer. I also bought a spare firing pin from Dave and just received it yesterday, so if the Geiselle hammer doesn't cure the issue, I will try modifying the firing pin to reduce the striking area and see if that help. Hopefully, one (or both) of those two things will cure this problem for good, because I really enjoy shooting this upper and would hate to give it up because of these random issues. |
| I built a new "dedicated" lower for my CMMG M4 .22LR upper using Geiselle SD3G trigger and took it to the range for another test. It worked much better today, and I only had about half a dozen misfires out of about 250 rounds I shot today (didn't have much time to shoot more). While it's a great improvement over my previous two trips, it's still not good enough by my standards, so my next step will be notching the firing pin tip a little to reduce the impact area and see if it improves the function even further. I really hope it does, too, because I'm starting to really enjoy shooting this gun, and it's quickly becoming my favorite. It's been a long time since I could go to the range and just blast away 600-700 rounds in one outing without seeing $$$ flying out of my wallet... :) |
|
Still not sure why you are having issues but of the many CMMG uppers I have and have tested, I have never had one that I couldn't shoot 600-700 rounds through without a problem. I use G.I. FCG's and one Kies MKl trigger.
If I had issues, I would send it to CMMG to get it running. There are no tweaks, cutting firing pins ect expected or needed. For those that insist on using after market springs, fcg's, you are on your own if I was CMMG. Dave N |
| We run just a cheap DPMS parts kit in the Aero Precision lower for our CMMG upper and never have failures of any kind..It will run 50 round drums mag after mag......Do get a rare occasional dud round but they are so far between I do not even know the last time we had one...I think when you start running two stage triggers and other mods to the lowers that is where you start creating problems that are not neccesary....They are alot of fun to shoot,thats for sure... |
|
I've fired maybe 600-800 rounds with no light strikes, then all of a sudden my wife gets 4 or 5 in as many magazines yesterday. Is there some way that the shooter can cause this, similar to limp-wristing a pistol? This is on an LMT lower with stock spring. Hammer is not notched. |
|
While still determined to make this upper work with my Spikes lower with Geissele SD-3G trigger, I decided to give a GI trigger a shot and see if it really solves all my problems like everyone keeps saying it would. The only lower I have with stock GI trigger is my 9mm SBR, so I pulled the mag block out of it to make it work with BDM magazines.
I thoroughly cleaned my upper again last night and went to the range this morning with both lowers. I started with the Spike’s lower first to see how it did today, and there were no surprises there – light strikes once or twice per magazine. After 3 or 4 magazines, I decide it’s time to try the GI trigger setup, so I swap the lowers, insert a fresh magazine, and slowly run through the whole magazine without a hitch… Now I’m getting all giggly and excited, slap a new magazine in there, and that’s when the fun starts. I fire a few rounds and then “click”. I’m thinking another light strike, go to clear, and then realize it’s FTE this time (failure to eject). OK, I’ve never had an FTE before, so it must something random. I clear it, insert another magazine, and a few rounds later – another “click”. FTE again. At this point, I start getting FTEs 2-3 times per magazine, some of which were pretty bad and required the empty to be pried out with a screwdriver. Below a is short video that shows some of them (not the best quality, since it was shot with my phone, and it’s a little difficult clearing malfunctions with one hand while trying to film it with another). http://youtu.be/fN5dfV7eE10 After about 5 or 6 magazines of this “fun”, I decide that I’d rather deal with light strikes than these FTEs, so I switch back to my Spikes lower. This is where things get completely weird. A couple of magazines later, I can feel that my bolt locked back. That’s weird, because I’m not running the BHOA… but the bolt is “locked back”. The video below shows the details of what’s going on. I write it off as a freak occurrence, and after getting it un-stuck and putting everything back together, I go back to practicing my malfunction drills. Then a couple of minutes later, it locks back again… Now I’m starting to get a little worried about it, but decide to just remove the forward assist thing (since it looked like it was locking the bolt up) and keep going and see what happens. And what happens next is this: http://youtu.be/fokF1G7SxL0 The guide rod is completely stuck all the way inside the tube. I tried tapping it lightly on the steel bench to see if it pops out, but it seems to be stuck for good. I didn’t have any pliers with me to try pulling it out, so I had to pack up and leave. Now, I have no idea if all these problems I’ve been having are somehow related and could be caused by a bad bolt, but it looks like a trip back to the factory is in order anyways, so hopefully they will be able to figure something out. I’ll try calling CMMG later on today when I have time and see what they say. In conclusion, while today's range trip sucked big time, I was able to at least further "document" my issues. Here's a quick summary: - With 2 different lowers with "aftermarket" triggers (one with RRA 2-stage trigger and another one with Geissele SD-3G trigger), I was having misfires/light strikes every 5-10 rounds (or in some cases more often). I've never experienced any other malfunctions with these lowers in over 1000 rounds fired. - With a lower with stock GI trigger, I was having FTEs (failures to eject) at least once or twice per magazine. Running this setup almost completely "cured" the misfires, but I still had one or two of them with this setup. |
|
Its a machine and anything can and will eventually happen. That is life. The good thing is that CMMG will take care of it for you. Sorry to hear of your problems. Wish you lived closer we could meet at the range and swap out some parts. I have several CMMG bolt assemblies and its easy for me to just change a part and zero in on the trouble spot.
Again, CMMG will take good care of you. OH, and a personal comment. (I don't work for CMMG, BTW) From your video it appears the problem is indeed just in the recoil spring and guide rod. I had this same thing happen once some time back on a "high mileage" rifle. All I did was to go to CMMG's site, fill out the form for a defective part, and they got right back to me. Sent me a new spring and guide rod PRONTO at no cost and I was back in business. CMMG is a great company. If you were to just get in touch with them and explain what was going on, they would take care of you. Its a LOT less time and trouble than what you put into all those posts and videos and it gets you fixed and running again faster. I know when I had a problem I went right back to them and it was solved in no time. They sell thousands of these things and statistically there will be a few that sneak by with a small issue. Its the nature of any machine. Go straight to CMMG and get your problem solved. |
|
Quoted:
Its a machine and anything can and will eventually happen. That is life. The good thing is that CMMG will take care of it for you. Sorry to hear of your problems. Wish you lived closer we could meet at the range and swap out some parts. I have several CMMG bolt assemblies and its easy for me to just change a part and zero in on the trouble spot. Again, CMMG will take good care of you. OH, and a personal comment. (I don't work for CMMG, BTW) From your video it appears the problem is indeed just in the recoil spring and guide rod. I had this same thing happen once some time back on a "high mileage" rifle. All I did was to go to CMMG's site, fill out the form for a defective part, and they got right back to me. Sent me a new spring and guide rod PRONTO at no cost and I was back in business. CMMG is a great company. If you were to just get in touch with them and explain what was going on, they would take care of you. Its a LOT less time and trouble than what you put into all those posts and videos and it gets you fixed and running again faster. I know when I had a problem I went right back to them and it was solved in no time. They sell thousands of these things and statistically there will be a few that sneak by with a small issue. Its the nature of any machine. Go straight to CMMG and get your problem solved. Thanks for your reply. I realize it's just a machine, and I know they fail from time to time. I did not post all of the above to just bitch at CMMG or to make them look bad. Maybe it seems that way, but it wasn't my intent. Yes, I'm a little frustrated with trying to get it to run 100% and the fact that my range trip was cut short because of this last issue, but that's about the extent of it. Well, that, and the fact that I probably won't be able to shoot the 3-gun match I was planning to and have to wait another 2 months for the next one... 
I posted it mostly to have all my issues documented in one place, for my own reference, as well as for others who may have the same or similar issues now or in the future, and the time I put into compiling all the data I have is worth it to me. I did just speak with CMMG a few minutes ago, and they asked me to send the bolt back to them to have it fixed or most likely replaced, so you're right, they are taking care of me, which I never doubted. I'll make sure to post an update once I get the bolt back and have the time to run more tests with it. |
|
I have experience mostly with Ceiners but your CMMG is mostly a copy most of my info carries over.
In my experience here are a couple things to look at. May or may not be your issue On some units the finish on the fireing pin "drags" on the spring that the fireing pin passes through. Polish the surface of the fireing pin (I use 0000 steel wool) A dirty or rough chamber will stop the cartridge just ever so slightly from being fully chambered and when the fireing pin strikes the cartridge the cartridge slides forward a bit and that movement somewhat lightens the strike Polish the chamber and eyeball it with a strong lens and a good light. Watch for the burr that gets raised on the rim when dry fireing and remove that burr if present. I do not use oil lube on a Ceiner as it seems to just gum things up with the crud from the 22. I clean the unit then hose it down with spray silicone spray lube. Just the normal cheap stuff you can get a home stores and big auto parts stores for $3 or $4 a can. Good luck! |
|
Somethimes it just seems that one set up won't work well with a lower. One of my customers got a complete upper. One fte after another. The BCG was replaced. Same issue. I sent him one of my personal BCG's and it worked great. Here is the kicker. The one he couldn't get to work was shipped back to me. I installed it in an upper and it ran 100%. I have no answer.
Dave N |
|
Quoted:
Somethimes it just seems that one set up won't work well with a lower. One of my customers got a complete upper. One fte after another. The BCG was replaced. Same issue. I sent him one of my personal BCG's and it worked great. Here is the kicker. The one he couldn't get to work was shipped back to me. I installed it in an upper and it ran 100%. I have no answer. Dave N Dave, you make a good point. Sometimes some things just don't make any sense. If we had lots of times and could just spend hours looking at each and every thing we might find the answers, but they are buried deep sometimes. I spent my career teaching others how to find root problems and fix them. Logic tells us that part "X" is bad and if we replace it or adjust it, all will be well. Problem is, in real life, sometimes finding the root cause turns out to be far more work than just popping in new part and moving on. Firearms seem so simple on the surface but once you start getting into some of the little details things get complex. I have hit walls before where I finally gave up and replace whole assemblies to solve a problem. I hated doing that but in the end its what you have to do at times. Life will go on. You will get this rifle fixed and you will soon have it off your mind and hopefully you can just forget it and move on. Live and learn. |
| Just a quick update. I mailed my bolt back to CMMG on Tuesday, they received it on Thursday morning and on Thursday afternoon I received a tracking number from them for the return. Not sure what's been done, but so far I'm pretty impressed with the turnaround. I should have the package in my hands on Monday. |
| Got my bolt back from CMMG yesterday and took it to the range this morning. It was the best range trip I've had so far with this upper, and while it still wasn't 100% reliable, it was a huge improvement over what it used to be. I shot exactly 750 rounds today and had 11 light strikes, 4 FTEs (failure to eject) and 1 FTF (could have been a bad round, it was crushed on the way into the chamber with the bullet side pressed against the feedramp). Not really sure what to try next to make it 100% reliable, but I may still try notching the spare firing pin I have and see if it helps any. I may also try a different lube as was suggested earlier and see if the dry silicone lube makes it run a little smoother. |