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Posted: 2/6/2014 5:09:38 PM EDT
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The weapon-
- Colt Match Target M4 Carbine - H Buffer - Colt F/A BCG - Troy L/P gas block w/ Troy TRX rail 
The issue- I have had issues with this gun since I got it back in '05 but it has been very inconsistent. With M855 green tip I seem to never have this problem. Basically sometimes the bolt stays back, sometimes it doesn't when I use any other type of ammo. I shot it today and out of the 120 rounds of independence 5.56mm and 20 rounds of Tula it happen about 10 times or so. A couple of times it didn't chamber a new round. I have tried 3 different BCGs and seem to have the problem with all of them. So, what do you guys think? buffer issue? I've read some people with this problem thinking it might be an issue with the bolt catch itself. Who knows, just trying to get the issue fixed because I really enjoy shooting this gun... The problem is that it is so inconsistent that it's hard to diagnose the issue... |
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If it truly is dependent upon ammo choice, it sounds like a matter of the gas system being right on the verge of not getting enough pressure to run things properly, and when you put lower pressure or inconsistent ammo in there, you get the inconsistencies in bolt hold-open and proper cycling.
Check your gas-key for leakage, tight fit and solid screws, check your gas rings and make sure that you aren't having excess gas leakage at the gas-block. If it still acts up, since you have an H-buffer in there, I would recommend changing it out to a standard carbine buffer and see what she does. You also have a F/A BCG, which is good and you should keep, but you have to consider that it adds weight that the gas-system has to move around, and combine that with all the other variables, and it might throw it over the edge into the land of inconsistent performance with lower-pressure loads You could have the gas-port opened up if all else fails, but that would be last resort imo. There are many ways to tune a rifle without messing with the gas port, and I would try everything else first. |
| I think changing out the buffer is my next move. I have already tried out 3 different BCGs and it hasn't helped the problem, I've also replaced the gas rings. It also originally had a standard FSP when I got it, so it doesn't seem to be a problem with the gas block. The gun came with a Colt Semi carrier, so the weight in the BCG doesn't seem to be a part of the problem. Thanks for the reply! |
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I think changing out the buffer is my next move. I have already tried out 3 different BCGs and it hasn't helped the problem, I've also replaced the gas rings. It also originally had a standard FSP when I got it, so it doesn't seem to be a problem with the gas block. The gun came with a Colt Semi carrier, so the weight in the BCG doesn't seem to be a part of the problem. Thanks for the reply! The gun isn't broke. You are shooting underpowered ammo. Tula is weak assed stuff. |
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The gun isn't broke. You are shooting underpowered ammo. Tula is weak assed stuff. Quoted:
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I think changing out the buffer is my next move. I have already tried out 3 different BCGs and it hasn't helped the problem, I've also replaced the gas rings. It also originally had a standard FSP when I got it, so it doesn't seem to be a problem with the gas block. The gun came with a Colt Semi carrier, so the weight in the BCG doesn't seem to be a part of the problem. Thanks for the reply! The gun isn't broke. You are shooting underpowered ammo. Tula is weak assed stuff. You are using cheap ammo in a rifle designed to shoot full capacity NATO rounds for years and years. How many rounds do you have through the rifle? |
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You are using cheap ammo in a rifle designed to shoot full capacity NATO rounds for years and years. How many rounds do you have through the rifle? Quoted:
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I think changing out the buffer is my next move. I have already tried out 3 different BCGs and it hasn't helped the problem, I've also replaced the gas rings. It also originally had a standard FSP when I got it, so it doesn't seem to be a problem with the gas block. The gun came with a Colt Semi carrier, so the weight in the BCG doesn't seem to be a part of the problem. Thanks for the reply! The gun isn't broke. You are shooting underpowered ammo. Tula is weak assed stuff. You are using cheap ammo in a rifle designed to shoot full capacity NATO rounds for years and years. How many rounds do you have through the rifle? It's hard to say I'd say a thousand rounds or so, it's not my primary AR. I understand that the other ammo is cheap and lower power, however my other ARs with eat through anything I put through it, so I guess I'm just use to that... |
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Yes, Tula is often weak ammo, but OP stated that it occurred with Independence 5.56 and Tula. If the problem was exclusive to the Tula, that would be different, but it's not, and a weapon that's choking on Federal labeled, IMI manufactured brass, is choking on ammo that it should be able to run.
Regardless, if OP wants to use Tula, than he is right to tune his rifle to run on it. I feed mine steel on a regular basis, and I wouldn't own a rifle that wouldn't eat it, or I would tune it so that it would. Nothing wrong with not wanting to be limited in what you can feed your rifle. |
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If it truly is dependent upon ammo choice, it sounds like a matter of the gas system being right on the verge of not getting enough pressure to run things properly, and when you put lower pressure or inconsistent ammo in there, you get the inconsistencies in bolt hold-open and proper cycling. Check your gas-key for leakage, tight fit and solid screws, check your gas rings and make sure that you aren't having excess gas leakage at the gas-block. If it still acts up, since you have an H-buffer in there, I would recommend changing it out to a standard carbine buffer and see what she does. You also have a F/A BCG, which is good and you should keep, but you have to consider that it adds weight that the gas-system has to move around, and combine that with all the other variables, and it might throw it over the edge into the land of inconsistent performance with lower-pressure loads You could have the gas-port opened up if all else fails, but that would be last resort imo. There are many ways to tune a rifle without messing with the gas port, and I would try everything else first. This all day. A standard carbine buffer is cheap and if your gas key isnt the issue I'd bet that the lighter buffer solves 95% or better of your issues. |
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I can't tell from your pic but if it has a Magpul BAD then that could be the problem. They're known for having that effect on some ARs. My POF was 100% no problems until I put a BAD on it, now it won't lock back when the mag is empty. Needless to say but I will be removing it.
If you are using a BAD try removing and seeing if it makes a difference. If you're not using a BAD, sorry I couldn't help. |
| If you can remove the bad lever to rule it out, i would do so. That said, it sounds like a gas issue to me. My colts and other ars all shoot everything from tula to my reloads to all the m whatever. Your gun should shoot fine with all of it. H buffer is what is in my carbines. Since you swapped carriers that also points to the gas tube is blocked, And yes it does happen, or to misaligned or loose gas block or incorrectly sized barrel gas port. Good news is its all relatively easy to fix, but it might take some work to actually figure exactly what it is. Good luck... |
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I think changing out the buffer is my next move. I have already tried out 3 different BCGs and it hasn't helped the problem, I've also replaced the gas rings. It also originally had a standard FSP when I got it, so it doesn't seem to be a problem with the gas block. The gun came with a Colt Semi carrier, so the weight in the BCG doesn't seem to be a part of the problem. Thanks for the reply! No. Your next move it to tell us how it operated before you installed the gas block and rail. Your sentence above makes zero logical sense. If your Colt ran fine before you fucked with it, logic states that the problem lies with the parts you fucked with. Seriously, WTF is up with your sentence in red I highlighted? It's....like.....completely illogical. |
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Dude, take deep a breath. If you read the original post, it says I got the gun in '05 and have always had this issue with it. SO when I had the standard FSP on it AND now with the Troy LP gas block, it has the same issue. Make more sense for you now? Quoted:
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I think changing out the buffer is my next move. I have already tried out 3 different BCGs and it hasn't helped the problem, I've also replaced the gas rings. It also originally had a standard FSP when I got it, so it doesn't seem to be a problem with the gas block. The gun came with a Colt Semi carrier, so the weight in the BCG doesn't seem to be a part of the problem. Thanks for the reply! No. Your next move it to tell us how it operated before you installed the gas block and rail. Your sentence above makes zero logical sense. If your Colt ran fine before you fucked with it, logic states that the problem lies with the parts you fucked with. Seriously, WTF is up with your sentence in red I highlighted? It's....like.....completely illogical. Dude, take deep a breath. If you read the original post, it says I got the gun in '05 and have always had this issue with it. SO when I had the standard FSP on it AND now with the Troy LP gas block, it has the same issue. Make more sense for you now? |
| And don't call it a 'Colt Match Target M4' like its a factory gun with a problem. Its way past being a factory gun since you have made major changes to critical parts. Whatever its doing wrong is the result of the modifications. My first guess is the new gas block. I believe your creation is significantly under-gassed. |
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Try different ammo and check the LP gas block. Check alignment of your gas block it could be canted slightly not allowing enough gas to cycle the weapon. Also check that you are using proper lubrication in case you are running dry because one it is a simple fix and two just because sometimes the simplest answer is usually the right one. |
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If it's short-stroking there are only 4 possibilities:
1. Undergassed. Pull the gas block and check the tube and make sure that it does not have any obstructions in it. Check the gas port in the barrel as well for size and obstructions. Swapping out of the BCGs and the gas block should have eliminated those as possible issues. 2. Oversprung. Simple as that, the spring rate is too high and a softer spring needs to be installed. 3. Overweight buffer. Again, this has not been eliminated as a possibility and a lighter, standard weight buffer may be needed to reduce reciprocal mass. If the gas system cannot overcome the static weight/spring combination then a lighter system needs to be in place. 4. Weak ammo. Tula is cheap because they skimp whereever they can on production costs, this includes the cheapest powders and lightest charges. They don't have NATO contracts to build for, so they can get away with light charges, knowing folks will have the attitude of "well, it's Tula, what do you expect?" Combination of the 4. Slight issues with all 3 can combine into a larger effect. That gun was designed to run hot ball ammo, my guess is a combination of a heavy system and lightly-charged ammo is causing the problem. |
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Check alignment of your gas block it could be canted slightly not allowing enough gas to cycle the weapon. Also check that you are using proper lubrication in case you are running dry because one it is a simple fix and two just because sometimes the simplest answer is usually the right one. Quoted:
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Try different ammo and check the LP gas block. Check alignment of your gas block it could be canted slightly not allowing enough gas to cycle the weapon. Also check that you are using proper lubrication in case you are running dry because one it is a simple fix and two just because sometimes the simplest answer is usually the right one. +1...I run H2 buffers in all my Colts 14.5" & 16" never had one single issue at all. Also never ran anything but 5.56 ammo Federal (XM193-XM855-MK318) and BH MK262 |
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It get's repeated so often everyone still believes it but Tula is NOT weak ammo. Tula velocities are actually almost as high as 5.56. The problem with Tula is they use powder with an improper burn rate which causes timing issues in some guns. Many guns will feed it fine however. I believe the biggest culprit is gas port diameter. Overgassed(even slightly) may be enough to mask the crappy burn rates used in Tula. As you mentioned in the OP however you were seeing issues with Independence which I do not believe is weak ammo. So it's possible there are other issues.
One poster suggested causes for short stroking but left out a few. Dragging components is one. Extra lube may help with this. Magazines can also cause short stroking. Magazines are the #1 cause for feeding issues in the AR. You didn't mention if you tried other mags. One way to test for short stroking is to either single load or only load one round in the mag, fire and see if the BCG locks back....every time. Maybe a Carbine buffer is all that is needed. Some mentioned a BAD lever but not sure if you use one. |
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As an enginerd, I agree with all you have stated above. Quoted:
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If it's short-stroking there are only 4 possibilities:.... As an enginerd, I agree with all you have stated above. <my best Elvis impersonation...> Welllll thank yah... thank you very muuuch. Nice to get backing from fellow nerdly types! 
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