Bolt locking to the rear question
 

I recently purchased a Rock River Elite Operator 2 AR-15. I took it to the range to zero and afterward did some range fire. After the third 30 round magazine, the bolt would sometimes lock to the rear as if it were an empty magazine (not empty though). This would happen three to four times with the next two 30 round magazines. I used the new RRA magazine and a new Magpul magazine, with the same results. The ammo is Federal 62 gr 5.56. In 30 years of firing M16 and M4's, I have never had this occur. I checked to make sure the bolt gas rings were not lined up and other than that, no mechanical evidence of something wrong. What could be causing this to happen and how can I correct it. Thanks

Do you have anything attached to the bolt release? For example a MAGPUL BAD? If so it maybe holding the bolt release up. Also without a mag in it does the bolt release spring back after you press it down? If not it maybe bouncing up during firing and grabbing the bolt.

Nothing attached to the bolt release, and spring is strong. ?????

Sounds like a bolt catch problem. When it locks back, is the catch engaged? It may be the catch wasn't machined (or cast) properly and the round is pushing it up.

Other thoughts - where do you hold the rifle with your weak (left) hand? Could there be any chance that your hand is hitting the catch?

Where did you buy it? If directly from RRA - I'd call as ask for a new bolt catch.

I have an email into RRA, since their phone stays busy. I have a feeling it's the bolt catch, I just can't imagine how its activating only sometimes by it self. Nothing is near the button while I'm firing.

Hmm. That's an interesting problem. It would not be the spring because the spring uses the tension in the other direction, to hold the bolt catch down. Unless it is somehow inconsistent with tension. As mentioned above it is possible that the catch is too big. With everyone and their brothers making AR parts right now and trading between each other for the cheapest contracts, there is a lot of garbage about.

Another issue could be the lower being out of spec. From experience, I have a rock river lower that the slot for the catch is very narrow. I had to shave the shelf of the catch to make it fit. That lower is pretty old, but who knows, could still be happening there. When you break the action, is the catch sitting flat on the lower? Is it really easy to pull it up? Does it get caught and bind?

It is pretty easy to replace if you have a small long punch and plastic tip hammer, or you could have a local gunsmith do it. It really should not take anymore than 5 minutes.

Interested to hear what it turns out to be. :munchin

Using the same green tip ammo (Federal XM855 from Lake City) 62 grain each time. Only happening once or twice per 30 rd mag, and only started when quick firing (multiple double tap). Unless someone traded the Lake City rounds in the can for identical reloads, I don't think its the ammo causing the problem. I'm waiting for Rock River to return my email.

Never fired a brand new M16/M4 or AR, is there some kind of break in period I don't know about?

Sorry, I changed my initial response to a different approach.

Well any gun has a little break in period to get it running slick. The first bit of wear normally they run better. However, in this case, the bolt catch is a pretty simple operation that would not be that affected by any kind of break in or wear.

If I were you I would just take it out of the lower and give it a good look. I know you bought a product and just want it to work, but sometimes, especially with AR's you have to put some love into them to get them running smoothly. If that catch is binding, just take it out and sand the edges that go in the lower with some fine sand paper. Then put it back in and see if it works better and moves more smoothly. Sometimes it takes some trial and error.

Also Buffer spring, and old magazines - Old mag springs may cause jam. Check for compression leak too?

Close Danger, interesting, how do I check for compression leaking?

Compression leak? Are you implying that the DI gas system is leaking somewhere, which is causing the bolt to catch?

I think if that was going on there would be short stroking.

I agree with the buffer and buffer spring as well.

+1 on trying different magazines.

RRA, Suggests that the bolt catch spring is sticking, allowing the bolt catch to bounce up and down. I lubed it up and will test on Monday. Other than sending the whole gun back, that's all I can do. Excellent customer service so far though.

You can drift the pin out and check the bolt hold open and spring, but if you mess up and knock one of the ears off, you will need a new lower receiver.

I wonder if RRA test fired it, and if so, how they let it out like that?

TR