AR Failure to feed

Scalloper

New member
I have a Rock River PP with a 20"bbl. I have owned the gun for 4 years or so. I have always had problems with ftf. Some times worse then others. Factory ammo,reloads its all the same. I have had the gun checked out by smiths 2 different times. After a thero cleaning at times I can shoot upto 30rds without any issues. When its feeding properly its a very accurate firearm. When its starting to have issues feeding the groups will open up. I have tried several different mags and at times it seems that some work better but some will hardly ever shoot more then 2-3 shots. What happens is the loaded cartridge will get stuck in the chamber but not far enough in to fire.
The last 2 days I have been trying different loads for accuracy. I put in a 5 rd mag and shot one shot at a time by dumping a round in and chambering with the bolt catch with no issues. Man was it accurate. I shot one 5 shot 300 yd group at .833 with 1 called flyer. Today I had about 5-7mph wind at 2 oclock and I shot 5 rd group at 3.47". At times I cannot do better then 2"+ at 100yds while loading from a mag. Any ideas why I am having issues when using a mag but not while loading singal rounds and chambering with the bolt catch lever? Somthing must be causing the bolt to jam somewhat and not have the needed power to compleatly chamber a round. At times a good amount of pressure is need to extract the loaded round.I clean the gun regularly. I dont think its happening because the gun is dirity. If its stripped down at times I can get off 20-30rds before I have a issue but not always.
 
I had similar symptoms with my wife's 6x45. Turns out the chamber was a touch tighter than the norm. I happened upon a different brand of dies and they were closer to this chamber. Not FTF OR FTE since.

Did the GS take any chamber measurements, cast the chamber, or mic some fired brass? This could tell you if this is the same problem. When clean, there is enough difference between clean and 30 shots of carbon to cause the hang-up.

Just tossing you an idea.
 
It's possibly a gas issue that is not forcing the bolt carrier group back far enough, or your action spring is slightly stronger than it should be...

Since the BCG has enough force to seat the round when dropped from a retracted position, it almost has to be one of the two above (or combination) involved...

I'm assuming that you are dealing with factory rounds, rather than reloads that may be underpowered...
 
I did wounder if the chamber might be a touch tight. No the GS did not do any of those things they (2 different smiths) cleaned the gun and pollished the chamber.Is there a chance it may get better after more use?
 
Originally Posted By: OldTurtleIt's possibly a gas issue that is not forcing the bolt carrier group back far enough, or your action spring is slightly stronger than it should be...

Since the BCG has enough force to seat the round when dropped from a retracted position, it almost has to be one of the two above (or combination) involved...

I'm assuming that you are dealing with factory rounds, rather than reloads that may be underpowered...
I have tried 6-8 factory brands and some of my reloads using SB dies.
 
I dont remember ever taking out the action spring. Is it common to clean the action spring?
I just removed the spring its clean with just a slight oil film on it.
 
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It's not something that will wear-in. It would need to be corrected. I would take it to the GS and have them clean up the chamber a bit with a good reamer. I don't figure this would be all too costly. There is always the route of letting RR check it out, but I'd just spend a buck or two and have a good AR oriented GS clean it up. PM AB_Bentley or R Johnson. Adam is starting to play with ARs and could clean it up, likely. And Ritch is a great guy with tons of AR experience.
 
Originally Posted By: ScalloperI dont remember ever taking out the action spring. Is it common to clean the action spring?

Do you mean the Buffer Spring? That is not a common practice. Even when we train with rifles, the manual just says wipe any visible debris. I don't think this is a cyclic system malfunction.

Do these rounds chamber after a bump to the FA? Even still, if it is SAMMI spec, all factory ammo should fit easily. Now, if the leade is a traditional 223, some longer rounds like 70 gr TSX And 60+ gr Steel Core ammo may be jamming the lands.
 
Originally Posted By: 1badsheeAlways worth checking around the gas key for a leak.

I'd assume the FA would remedy any short stroke. Not the case, here. But a good idea.
 
Originally Posted By: ScalloperI did look 2 of the bullets over better today and a FMJ had a deep scratch from the neck toward the tip.

That's likely from the feed ramps.
 
I may have found the problem. I took the gas block off and noticed some carbon on the barrel. It looks like mabe the gas block was not getting a good seal so I realined the block cleaned the block and gas tube, cleaned the bolt and lightly lubed the bolt and fired 30 rds without a glitch. It even sounds like the action is working cleaner.
 
Originally Posted By: ScalloperI may have found the problem. I took the gas block off and noticed some carbon on the barrel. It looks like mabe the gas block was not getting a good seal so I realined the block cleaned the block and gas tube, cleaned the bolt and lightly lubed the bolt and fired 30 rds without a glitch. It even sounds like the action is working cleaner.

In my 40 years shooting and working on M16s and AR-15s, I've yet to see a rifle that didn't show some signs of carbon blowby at the gas block/front sight base, or on the gas tube. It's actually quite normal, and self-limiting. Once the carbon fills up any airspace, it stops the blowby.

If your rifle won't work with factory ammo, I'd suspect the chamber to be on the tight side, based on what you've said. I'd call RRA, and explain the situation to them. I bet they'll take care of it.
 
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