AR Sponsor
Posted: 2/3/2014 6:51:28 PM EDT
|
Hello to all,
I'm having issues (short stroking/jamming) on my CMMG upper. After about 15 or so rounds it appears to begins to short stroke getting worse every time I pull the trigger. Can't figure it out cuz it's basically a new upper with hardly any rounds put down the throat at all. On my next visit to the range I've now gave the chamber another chamber cleaning so I hope that will make things better but I just had a flash......could the short stroking be caused by bad gas rings????? I checked those too and made sure the gaps on each ring doesn't line up with each other. In addition I'll take another completed BCG "nickle boron" that won't work in my Double Star upper. It kinds appears I may have a gas leak somewhere in the system BUT if it was a gas leak wouldn't it jam on the first round fired instead of happening after 15 rounds???? Assuming the gas tube and it's connection/seal in the front sight post is good could it just be the gas rings causing the issue???? On my next range visit if it short strokes again I'll try and swap bolts again and see what happens. If I get no joy I'll just turn it in to the range in house gunsmith and have him work on it. Any ideas? It doesn't appear the gas key is leakiing cuz I see no odd ball stains near the gap. I don't see any issues up fromt near the front sight either? Impala 
|
|
Quoted: Uh.... more like 3-5k for gas rings on a carbine. Quoted: Quoted: Typically I hear of about 20-30K rounds. Uh.... more like 3-5k for gas rings on a carbine. |
|
Quoted:
Uh.... more like 3-5k for gas rings on a carbine. Quoted:
Quoted:
Typically I hear of about 20-30K rounds. Uh.... more like 3-5k for gas rings on a carbine. On the internet that's what I hear. In the real world not so much. I sold a carbine with around 5K rounds on it and it didn't feel loose nor were the rings showing signs of wear. On top of that, both 1500-2000 round courses I went to, I never saw anyone's weapon have issues with the gas rings (15-20 people each class). Did they always replace them after their last class? Were all of the guns brand new? No, and no. This is an internet problem. Now, if I were using the weapon and depending on it with my life is 3-5K a good replacement interval? Sure. Why not? They are cheap. I personally don't know anyone who wore out any gas rings though. They typically replace the barrel and bolt at the same time and rock on. Check out Filthy 14. They never replaced the gas rings. The bolt broke at 16,400 and of course it got new rings then, otherwise, nada. Did just fine. Unless you have a problem with your carrier or something is out of spec, it'll do just fine without messing with the rings every few thousand rounds. |
|
Hello everyone,
Thank you for your fast replies. Every posting offers possibilities but I admit I'm still perplexed especially the one about the buffer weight. If it was the buffer why would the rifle begin to fail after 15 rounds and progressively get worse after every shot fired??? The other question regarding lube. I feel I apply plenty of lube. I clean and oil the bolt rails and the gear portion of the bolt with allot of oil compared to what is described in the field manuals despite the reasoning to use excessive oil. Every part of the BCG is lubed that would effect performance. On my next outing I'll add more on the rail portions and see what happens including the inside to where the gas rings rides. Based on my assessment and the suggestions to use more oil I see no reason why I can't get past 20 rounds at least! Anyway I still have a couple weeks before I re--oil the rifle before I head out again. I'll keep you folks up dated as time goes on. After all I have another bolt to try and toss in if the original goes sour. Keep your posting coming. I need more thoughts on this. Something is making my rifle short cycle and it usually happens after about 15 rounds fired. Impala |
|
Quoted:
You could have any number of problems at this point. Swapping BCGs to see if the problem moves can’t hurt. If you let the weapon cool down can you fire another 15 rounds or so? PFC, When the issue (jams) began I did put the rifle down to ponder why it was giving me problem after only 15 rounds or so? Since I have another BCG that gave me probelms in another rifle upper before I will give it a try cuz your right....I have nothing to loose at this point. When I operate the bolt by hand I know it can't be the gas rings but as always I can be wrong. These rings will hold. Again after my experiment if things still goes sour for me I'll turn it in to the on-site gunsmith and just have him work on it. I just wish I had enough room and the tools to work on it myself but I admit I don't have the necessary knowledge. I only know the basics of the gas system but that all. The only thought I still have is that my PMC Bronze ammo is bad! Maybe just maybe I bought a bad lot but then again my buddy right next to me was shooting the same ammo in his AR and was working fine. Who knows......bad ammo, too heavy a recoil spring, bad gas system??? Heck I wish CMMG was located in the Los Angeles area then I could turn it in to them and they'll probable fix it in an hour! Impala |
|
Your saying the upper is almost new rings the alarm bells for me .
The only thing changing much in 15 shots is lube getting slung off the parts. Could be the gun is just tight , with lots of extra oil it starts out ok but after 15 shots some gets slung off and things start dragging . With a new gun lots of the moving parts are tight and have a few rough spots on them . Some new guns work fine from the get go and some are fussy as anything for a while. With a new gun start with a known good used magazine , full power ammo like Federal XM193 and of course start with it clean and a bit heavy on the lube. Shoot 200 or 300 rounds adding a bit more oil if it starts to hang up . You might have a few failures and hang ups but don't worry much until you get some rounds through it. Once a AR gets broke in you should be able to take a clean lubed rifle and shoot up several hundred rounds without thinking of adding lube but a new tight gun can sometimes needs a bit of help until the parts wear in some Gas rings are some of the key parts but don't get all anal about lining up gaps and replacing rings . I have seen rifles with truly messed up rings that still worked just fine . Gas tube or loose carrier is a more likely problem area . Short version: With a new gun clean , lube , shoot good full power ammo and good mags and get 2 or 3 hundred rounds downrange |
|
Quoted:
Your saying the upper is almost new rings the alarm bells for me . The only thing changing much in 15 shots is lube getting slung off the parts. Could be the gun is just tight , with lots of extra oil it starts out ok but after 15 shots some gets slung off and things start dragging . With a new gun lots of the moving parts are tight and have a few rough spots on them . Some new guns work fine from the get go and some are fussy as anything for a while. With a new gun start with a known good used magazine , full power ammo like Federal XM193 and of course start with it clean and a bit heavy on the lube. Shoot 200 or 300 rounds adding a bit more oil if it starts to hang up . You might have a few failures and hang ups but don't worry much until you get some rounds through it. Once a AR gets broke in you should be able to take a clean lubed rifle and shoot up several hundred rounds without thinking of adding lube but a new tight gun can sometimes needs a bit of help until the parts wear in some Gas rings are some of the key parts but don't get all anal about lining up gaps and replacing rings . I have seen rifles with truly messed up rings that still worked just fine . Gas tube or loose carrier is a more likely problem area . Short version: With a new gun clean , lube , shoot good full power ammo and good mags and get 2 or 3 hundred rounds downrange nhsport, yeah what you say is true but in my opinion I'm drowning my bolt in oil and do allot of hand cycleing to make sure things work smoothly. As for the ammo that's what I had thought of all this time before that the PMC Bronze is weak cuz when I change to PMC Target ammo the rifle perked up and began to cycle properly instead of short stroking. In addition I had a box of old Winchester white box and to my surprise it malfunctioned on that too! Just in case I'll take another BCG with me and see what happens. No use trying to sweat over it cuz I can't bust any caps until the end of the month anyway. When the time comes around I'll re-lube the bolt again to make fully sure to cover that area. Again if nothing goes right for me then it's off to the gunsmith for me. Impala |
|
Quoted:
What buffer & spring combo are you using? Seriously, start with the obvious!!! Tell us about your lower. NoVaRight, I have a LMT lower and to tell you the truth I can't say what buffer/spring combo I have. When I first took it out to the range I must admit it seemed heavy but so far I've taken it out twice so far and with the limited amount of rounds put down range it appears to have lighten up to the point that it seems no heavier than my other AR's. If you thinking that I have a heavy recoil spring and buffer then perhaps your right BUT if that's the case then why would it begin to hang up on me after 15 sucessful firings??? I admit I'm no expert cuz you could be right. Keep your postings coming cuz I'm learning as I go. Now that you mentioned it I could switch lowers to see what happens. Jee wiz I should have thought of that during my last range secession! What a dope I've been:-( Impala |
|
Quoted:
10 would be a better estimate, thats about how long they last in the m16 blaster uppers, except for the 5.45 Quoted:
Quoted:
Quoted:
Typically I hear of about 20-30K rounds. Uh.... more like 3-5k for gas rings on a carbine. What is what the Colt replacement schedule looks for so what I expect. If they last longer, so much the better. |
AR Sponsor