AR feed problems...

[breakingcontact]

I'm sure the biggest contributing factor to the somewhat early wear (I've heard of worn rings giving people short stroking problems as early as 1k) is all those dusty windy days at BOTW

Looks like Guns+ is the only thing up here open tomorrow so I will have to check give them a call and see if they have any. If not I'll check out AGL tuesday (if they aren't closed for xmas eve).

Ah. AGL is normally closed on Mondays

 

[rushthezeppelin]

Guns+ had em. Picked up two sets and the once in my bolt during my lunch break. WAY tighter seal now. Might make one more range trip tonight to do some more testing.

Sent from my Samsung Galaxy S III

 

[rushthezeppelin]

For reference here the old set next to the spare set I bought.

Bottom ring was a whole 0.020" smaller measuring with my reloading calipers.

Sent from my Samsung Galaxy S III

 

[breakingcontact]

For reference here the old set next to the spare set I bought.

Bottom ring was a whole 0.020" smaller measuring with my reloading calipers.

Sent from my Samsung Galaxy S III

So does it run right now?

 

[rushthezeppelin]

Not going to make it to the range today unfortunately so I don't know (unless I want to take out a few more doorknobs in my house :P). Anyone know if any ranges are open Christmas day? Not like I have much of anything else to do since my roommates are up in DFW.

 

[gdouthit]

(unless I want to take out a few more doorknobs in my house :P).

Doo eet

 

[rushthezeppelin]

Gahh apparently nobody scheduled any jobs with us for Xmas Eve and I'm almost positive no ranges are open. Guess I'll just spend the day reloading (or at least catching up on all the 223 case prep I need to do).

 

[Savage805]

Eagle Peak says it's open 10:00-8:00 365 days. Need a place to shoot that new xmas present.

 

[rushthezeppelin]

Eagle Peak says it's open 10:00-8:00 365 days. Need a place to shoot that new xmas present.

Only reason I go there is looking for powder. You have to pay twice the price too your first time on the range and they only take cash. Idk of its worth 30 bucks, 2 gallons of gas and an atm fee to go there.

Edit on the gas amount

Sent from my Samsung Galaxy S III

 

[Reaper277]

I had the same problem a few years back, it turned out that the gas port on my barrel wasn't fully lined up with the gas port on the FSB. The FSB was a JP enterprises, I had to drill the port open more and it fixed the short stroking problem.

 

[rushthezeppelin]

Well gas rings didn't fix the issue. Still short stroking about 1 in 8 or so rounds. It wasn't missing the feed entirely as much as it was before though, more rounds grabbed on extractor groove causing the nasty jam. Got home and took the gas block and tube off, ran pipe cleaner with solvent and the damn pipe cleaner came out almost spotless. Went ahead and stopped eyeballing the gas block and made some alignment marks on the barrel with a 223 case head (brass marks the barrel beautifully). Still don't see how this could be the problem even if it was off by a decent bit though as the port in the Troy gas block I have is generously sized. Everything fits tighter than a you know what (so tight I have to use a mallet and a block of wood to remove and reinstall the gas block).

If this don't work I'm probably going to have to take it to a smith and probably have the gas port drilled out a bit. I've basically gone through the entire gas system almost twice now trying to diagnose this crap.

 

[breakingcontact]

That stinks man, was hoping you got it running. You've become very familiar with the rifle through all of this at least! You going to lunch tomorrow?

 

[rushthezeppelin]

This is very true. I know my rifle very very personally now. Just hope she decides to stop being a royal bitch and get over her winter PMS

And yes I should be able to make lunch tomorrow.

 

[M. Sage]

Just curious, how long have you had this rifle, and how exactly have you been maintaining it?

 

[rushthezeppelin]

About 10 months and she gets a good cleaning after almost every outing (taking bolt apart and running patches down bore till they come out pretty clean, every few times brushing the bore). Usually shoot 70-100 rounds a range trip so she hasn't been run too darn ragged or anything. Never had a problem with major amounts of carbon buildup at least on the bolt and apparently not in the gas tube either. Probably the worst thing I did was forget to put a drop of lube down the gas key for about 500 rounds before this problem started but the bolt itself was still very well lubed. She ran flawless until right around the 1k mark when I decided to put steel case in her (at Hicksville) and had a few hickups with that caused by gashed cases leaving a bur that prevented full chambering (I'm guessing based on the direction of the gashes that the bolt was nicking them on its way out of battery). Then she ran fine with brass for another 300-350 rounds and then this problem started happening.

Probably the only thing I haven't done in terms of cleaning yet is try and use a copper solvent in the bore, never really see that green oxidized color on my patches though, just carbon black so I've assumed (perhaps wrongfully so) that I don't have enough copper fouling to worry bout. Pretty sure the gas port ain't clogged with any of that. I made sure to look down the barrel when I had the gas block off this last time and there's plenty of light shinning through the gas port.

 

[Shorts]

Rush, gas pressure is the backbone of operation for the gun. Do not under estimate it.

Sounds like the gas rings and digging into the gas system has somewhat improved the performance if you're only getting 1 in 8 instead of every other round. You are on the right track. We need to find the other issue contributing to the errors. Don't worry, just a matter of time, keep working on it. At the end of the day the rifle is a bunch of parts totally a machine. If one part or several parts aren't right they mess up the entire machine.

For reference:

- carbine gas system = port size should be .063"
- carbine buffer = 2.9oz
- carbine spring = should be a length of 10-1/16" to 11-1/4"; too heavy a spring can cause problems


True causes of short-stroking then we are talking about a malfunction of the gas system or underpowered ammo.

1. FSB or gas block is loose or blocking the gas port. = you aligned the gas block and cleaned the gas tube

2. Undersized gas port. = have you actually measured this yet?

3. Worn gas rings. = you have installed new gas rings

4. Bolt carrier key is leaking (loose). = ?

5. Faulty gas tube. = ? Have you pressure tested it? A hairline crack is enough to cause problems.

6. Crappy ammunition. = ? Are you using the same ammo with each function test? If not, that adds to the variables.


How much force are you inserting the magazines with? It is possible to over insert the mag that the feed lips interfere with the bolt. It drags and loses energy and doesn't go far enough back to strip the next round. I don't think the problem would manifest all of a sudden if over inserting mags was the case. This is just merely a technicality to mention it. I also think you'd have issues with not locking back.

Feed ramps that are sharp or have a bur on the edge can grab rounds and FTFeed. I don't think this is the case either as you'd have been seeing it long ago. Again, technicality just to mention it.

And just so it is put out overgassing can cause short stroking. Tell tale signs of overpressure are mangled rims and flattened or leaky primers. But it is less common of a problem. In all likelihood you are dealing with an underpressure condition which warrants checking all the items above. That said, what do your spent cases look like?

Have you tried a different BCG?

 

[rushthezeppelin]

Don't want to speak to soon but I've found another part out of spec (if it was by enough, IDK). Went ahead and picked up a new gas tube for 15 bucks at AGL today. First did a check in my bolt of old vs new. Old one was a loose fit, new one took some a wee bit of force to get in so definitely a better seal there. Old one measured a hundredth smaller than the new one. Perhaps I got premature wear on the old when my gas block got out of alignment. At least it wasn't so far off that I had the worst case scenario for that (which I saw at hicksville) of the gas tube and gas key getting marred to hell but it still might have been enough to break that seal enough to cause gas leakage.

Definitely didn't have the signs of overgassing (rims are quite blemish free and no flattened primers on factory loads) so I'm thinking this might be might ticket to a happy AR. We shall see though on my next range trip.

 

[M. Sage]

Don't want to speak to soon but I've found another part out of spec (if it was by enough, IDK). Went ahead and picked up a new gas tube for 15 bucks at AGL today. First did a check in my bolt of old vs new. Old one was a loose fit, new one took some a wee bit of force to get in so definitely a better seal there. Old one measured a hundredth smaller than the new one. Perhaps I got premature wear on the old when my gas block got out of alignment. At least it wasn't so far off that I had the worst case scenario for that (which I saw at hicksville) of the gas tube and gas key getting marred to hell but it still might have been enough to break that seal enough to cause gas leakage.

Definitely didn't have the signs of overgassing (rims are quite blemish free and no flattened primers on factory loads) so I'm thinking this might be might ticket to a happy AR. We shall see though on my next range trip.

What part of the bolt was .100" smaller than the other? That's a LOT of material. Honestly, I wouldn't rush to chalk that up to wear, DPMS hasn't been real good about quality control the past couple years. Odds are good it left the factory that way.

+1 to what Shorts said about the bolt carrier key. I don't expect the gas port to be undersize. More often than not, this rifle is overgassed by a fair amount with an oversize gas port. Very common, especially in the lower-end carbines.

 

[rushthezeppelin]

Not the bolt, the end of the gas tube where it fits into the bolt. Also I said a hundredth not a tenth, pretty sure the gas tube aint even a tenth thick. There was no discernible wear on the inside of the key itself. Gas key itself I still tight as ever. I ALWAYS check the position of the bolts when cleaning and they haven't budged a bit despite the staking looking to be on the minimum size. Like I said I ain't jumping to conclusions that I have everything fixed yet but that better seal on the new gas tube seems to be a good sign. If I do continue to have problems I will probably look at the possibility of overgassing , but as I stated I am showing no signs on cartridges of overgassing. Curious though why would overgassing (especially with lower powered 223) show up so late in the game, does this happen often?

 

[M. Sage]

So the gas tube was shorter, or smaller in diameter at the back end?

Doubt it was wear, that's a part that shouldn't ever wear out, honestly I'd be surprised if it made solid contact with the key...