AR not cycling correctly...please help

[Racefiend]

Hi folks, wondering if I could could some help from the AR experts. I have 1 AR (M16A1 clone, Doublestar upper) that will not cycle completely. Never has since new. You can watch the bolt and it will not come back far enough. Sometimes it will stovepipe, but most of the time it just reinserts the empty brass into the chamber.

I have another AR (m4gery, also Doublestar upper) that works fine. I switched uppers/lowers/bolt carriers around and found that the problem always follows the bolt/carrier. When I put the problem BC into the M4gery, it will cycle far enough to eject, but not far enough to pick up another round, so I end up with an empty chamber. This must be due to a weaker recoil spring in the M4.

Comparing the two in their respective rifles, they feel and function the same when charging, no perceivable difference in drag or anything. Manually pushing/pulling the bolt within the carrier is no different either, though the problem bolt feels a little dryer, but no harder to move. There is no abnormal wear on the bad BC when compared to the good BC. However, there is a difference in the way they are wearing on the bottom of the BC. I don't know if it means anything, but here is a picture of them:



The top BC is the one that works fine. You can see it is only wearing about half the width of the bottom carrier (the problem BC).

I'm stumped. Anyone have any suggestions? Could it be as simple as adding a little oil to the bolt? Did that and it seems a little smoother. Haven't test fired it yet, though.

Thanks

Christian

[xnv733x]

i was just dealing with the same problem im kinda new to all of this everyone told me to try changing the buffer and spring although i found that i had a missing gas ring (bought a used upper ) i bought a brand new bolt cleaned and lubed everything havnt had a problem since

[FMJBT]

Check the gas key on the top side of the bolt carrier. It should be torqued down tightly with the screws staked in place to prevent them from backing out. Check the rings also. A brand new bolt should not have issues with rings wearing out, but if it's missing a ring or two it will not seal properly.

[bornproud]

Check the gas rings, make sure the slots in the rings do not all align up in one spot, seperate them. Try different ammo. Make sure carrier key and the hole from the carrier key into the bc is cleann and unrestricted. (Sorry, I am haveing trouble putting my mind into words. Take a piece of guitar string and thread it through the carrier key into the bolt carrier to make sure there is no carbon build up) If all else fails get an M1A.

[damon1272]

I had much the same problem with my RRA. After messing with teh gas system to no avail a call to RRA solved it real quick. Their response was to make sure the buffer tube was well lubed especially if it was a new rifle. I had out what I though was a good amout of oil down the tube when I assembled it. I took their advise and put a good amout of oil down the buffer tube. This solved the problem and after the rifle was broken in I have run much less oil in the tube with good results. Give it a try.

[Racefiend]

Thanks for the suggestions so far.

Checked all of the above. Key bolts are snug as a bug (in a rug). Gas rings are all there and gaps are not aligned. Key hole is fine, I can blow right through it with ease.

As far as the buffer tube goes, the good BC works in either rifle, so I doubt its buffer tube, FCG, or the gas system of the upper itself. The ammo I used is the same with any tests. It's something with this one BC.

Oh, and an M14 is already in the works Working out a trade deal on a Polytech.

[TRAP55]

Gas tube and key need a snug fit. Remove the key and slip it on the gas tube, it needs to fit like a piston in a cylinder. Or use the key off of the bolt that works and see if that cures it.

[aplinker]

Please don't lube your receiver extension with oil.

Check to see that the bolt is snug in the carrier by pulling the cam pin and seeing if the bolt will fall out.

Check to see if the gas key mates properly to the gas tube.

Lastly, your carriers seem dry. They should be WET.

[stphnman20]

Lastly, your carriers seem dry. They should be WET.

Feels better when they are wet!!

I mean lubed!

Man that doesn't sound right! lol

[ar15barrels]

You should be able to look into the ejection port of any AR and see the wet oil track like in my 3gun rifle:



If you look close, you may also note that my rifle is a little dirty.
It's due for it's annual cleaning in January.

[Racefiend]

I'll lube it up some more and try it out this weekend. If that does not work I'll switch the gas keys and hope for the best. Will update later. Thanks again so far.