I just got back from a PD shoot and while there started to experience a cycling problem with my .204 Ruger AR.

Using factory Hornady 40gr cartridges that have never caused a problem before, the bolt carrier started to fail to cycle back far enough to pick up the next round from the mag.

I tried the same mags in my .223 and they functioned fine, the only thing I can think of is that the Action Spring is getting stronger(?), I removed it and it was not dirty, etc, and the buffer was moving easily.

Can the bolt carrier be a problem and if so, where do I focus my attention?

I had the same thing happen on my 223 upper, It was the gas block, It wasn't lined up over to gas port properly. I had to move about .002, (It don't take much). If you hit the block you may have moved it enough to reduce the blow back.

Hope this helps


MIvarmint

Lack of lube can cause this also. If you dont plan on low crawling thru sand, keep the bolt wet with lube.

i would check the gas block and then would check the gas key on the bolt see if it is tight and crimped.
good luck,
Clint

How meany rounds was fired through the gun before a total cleaning was done. Last year at the WW 2005 PD shoot in WY. mine and one of the other guys AR-15 started acting up around 250 rounds, had to do a total cleaning and it worked fine after that. GENE'O

First thing check the carrier gas key. Make sure it is tight. Most are staked but can loosen up and allow gas to excape. If it is loose and you can remove the screws clean them and degrease. Re-install with blue locktight.

Next check the gas rings. The way to test them is to remove the firing pin and cam pin. Have only the bolt in the carrier. Position the bolt to the out (unlocked position). Then set the bolt and carrier on the work bench (verticle) with the bolt face on the bench. If the weight of the carrier caused the carrier to slide down over the bolt, the rings are bad.

Always insure that the ring gaps are NOT lined up when you clean and re-assemble.

If this doesn't help let me know and we can proceed further.
Good luck

Thanks Guys, I think I may have found the problem, but won't know until I can get to the range later this week.

I had thoroughly cleaned the bolt carrier before we left on the trip and used some Tetra grease recommended by a friend and, I thought, had wiped it down thoroughly before re-installing it in the upper.

Apparantly, when it gets hot, it liquifies and than solidifies as the bolt carrier cools down causing a really gummy residue on all surfaces as when I just tore every thing down a few minutes ago, the whole carrier was very sticky.

I checked the gas block and the rings according to the suggestions and all appeared to be OK.

I'm chemically stripping the carrier group and lubing it with a lighter oil and will take it to the range after tomorrow.

Again, thanks for the suggestions as I hate it when something doesn't work as it should. Hopefully my problem will be solved... It's just too bad I had to leave a few PDs due to not having a good follow-up shot on the pairs and triples.