Two AR questions... [Archive] - M4Carbine.net Forums

alank2

09-09-11, 10:36

Hi,

The first is that I noticed there is quite a bit of play in the bolt catch. When not holding the bolt you can wobble it left to right a bit. When the bolt is held open, it puts a lot of force on the bolt catch. Is the aluminum receiver capable of taking this force fairly well day in and day out?

The second question is that when letting the bolt go forward slowly, I noticed that is an area where the bolt is about midway in the ejection window that is seems to want to hang on a bit. It isn't rough, but instead of one smooth same force all through the stroke, force seems to lighten slightly as it wants to stay in the middle a bit and then take off again. What causes this?

Thanks,

Alan

Belmont31R

09-09-11, 10:44

No issue with a little bit of play in the bolt catch. Normal.

The BCG comes into contact with things along its path forward. The bottom of the BCG rubs on top of the hammer, and bolt rotates.

If the gun is fairly new its normal to be a little rough in spots. As the gun is used more those areas will smooth out, and the action will ride a lot better. If you look at the inside of a well used upper or the outside of a BCG you'll see shiny spots where the metal has worn. I tend to put a little bit of lube on those spots as it indicates wear and friction areas.

thopkins22

09-09-11, 10:45

Hi,

The first is that I noticed there is quite a bit of play in the bolt catch. When not holding the bolt you can wobble it left to right a bit. When the bolt is held open, it puts a lot of force on the bolt catch. Is the aluminum receiver capable of taking this force fairly well day in and day out?
Yes, it's perfectly capable of taking it.

second question is that when letting the bolt go forward slowly, I noticed that is an area where the bolt is about midway in the ejection window that is seems to want to hang on a bit. It isn't rough, but instead of one smooth same force all through the stroke, force seems to lighten slightly as it wants to stay in the middle a bit and then take off again. What causes this?

It's the bolt carrier interacting with the hammer. As it closes further, it's the cam pin interacting with the upper receiver. Both will become less noticeable with use and lubrication. Nothing is wrong. Presumably it works when you shoot it? Then don't worry about it.

alank2

09-09-11, 10:53

Hi,

Thanks guys, it works perfectly, just trying to get to know the platform!

Alan

browneu

09-09-11, 11:10

Questions answered.

Sent from my LG-P999 using Tapatalk

alank2

09-11-11, 19:39

thopkins22

09-11-11, 19:50

Hi Everyone,

Not to ask again guys, and it has been working fine, but the left right movement of the bolt catch is about 1/16" if you push it from its extreme left to its extreme right while not under any pressure. Is this on par with other rifles or are other rifles about the same?

Thanks,

Alan

It's fine and normal. There is some difference between different rifles, some are tighter some are looser. But it's not a defect, blemish, nor a future problem.

billybob19606

09-11-11, 19:51

I notice the same things...Mine's new (only 100 rounds thru it).
Will probably get smother once it breaks in..

Dunderway

09-11-11, 20:07

In my limited experience, bolt catches from sub-standard mfg.s like DPMS and CMMG have HUGE pin holes in them that cause a ton of slop. All, including quality mfgs, seem to have some movement, but the cheap ones like DPMS are excessive.

I have replaced all of mine with LMT. I'm surpirsed that I have never read anything glowing about the LMT bolt catch, because it is really an improved design (in my mind) and a work of art for such a simple part. It has a much improved geometry over the standard Colt design, and has much tighter tolerances than the cheaper mfgs.

ETA: The engagement surface of cheaper BCs can also have VERY heavy machining marks, where higher end parts usually will not.