Bolt carrier "catching"

AR/M4 AR Technical Discussion
1

I decided to get an old AR15 out of the safe to service it (was built 25 years ago from parts and havent shot it in a few years).

I pulled the charging handle back and the bolt/carrier “caught” half way forward. It only does this when I “baby” it forward and cycles fine when fired and charged like normal.

I pushed down on the action spring and buffer - all seems fine there. I then removed the charging handle and moved the carrier through the upper receiver. In a certain spot it did seem to hang.

A visual inspection of the carrier and upper receiver revealed no flaws that my inexperienced eye can see.

Thoughts?

2

Could be the hammer.
Could be the bolt catch.

Simple fix, stop riding the charging handle forward.
You’re not supposed to do that anyways.

3

I am aware that you are not supposed to do this when charging an AR15 :stuck_out_tongue: However, my other 2 AR15s do not do this. Therefore, i have concluded this is not normal and want to fix the problem, if there really is one. I enjoy diagnosing and fixing my weapons so that I am better versed and knowledgeable with the AR platform. :happy:

4

Do you have a funky mutilated BCG and a notched hammer maybe? Why not give us more details about the upper/lower, etc… so we can help?

5

Sorry, wasnt sure what, if any, details would be necessary. I did not personally build this gun (uncle did) so I do not have alot of details.

Upper - RRA with Colt barrel. Unknown semi BCG.
Lower - junk cast Olympic. Unknown LPK. Standard “un-notched” hammer

6

Can you show the bottom of the bolt carrier?

7

I couldn’t get rid of that LOWER fast enough. :nono:

8

If it’s pre-ban he could fetch enough to buy a complete BCM lower.

9

Looks like there is some excess wear on the top of the bolt carrier tail, wonder if its hanging on that screw in the upper for the BUIS?

10

The charging handle would cover that.

11

Good point, could be something with the detent. OP fan you get us pics of the receiver extension and detent.

12

It is a pre-ban lower, which I dont know much about. I dont have much desire to modify this frankengun since its a back-up, back-up, AR15 and it holds some sentimental value. But i’ll consider it :slight_smile:

13

Sorry for the poor quality photos, they are done on my junk phone. And thats for the help!

14

I have seen this before and its usually the retard bolt carrier snagging or dragging on the hammer.

15

Hunk that POS carrier get a new one “shrouded”. semi or not.

16

+1, now that I have my rifle it looks like where you BCG is getting stuck is right where the cut is on the bottom to keep you from going full auto, I have a feeling that cut is allowing the hammer to ride the firing pin causing the issue.

17

What does “riding the CH forward” mean? Pulling BCG back and letting her fly without a loaded mag installed?

][/b]QUOTE=polymorpheous;1452427]Could be the hammer.
Could be the bolt catch.

Simple fix, stop riding the charging handle forward.
You’re not supposed to do that anyways.[/QUOTE]

18

[/QUOTE]

Riding the CH is when you dont let go of it and ride it forward.

19

Riding the CH is when you dont let go of it and ride it forward.
[/quote]

Excuse my lack of knowledge but why is that bad per sey? I was always under the influence that letting the BCG (pistol slide too) drop foward without a round in the magazine to chamber it and slow it down is what’s bad?

20

Excuse my lack of knowledge but why is that bad per sey? I was always under the influence that letting the BCG (pistol slide too) drop foward without a round in the magazine to chamber it and slow it down is what’s bad?[/QUOTE]

It doesn’t hurt the AR-15, what happensgenerally when riding the CH is it will not have enough force to strip a round from a magazine, and can sometimes cause other issues with chambering.

The BCG will slam home even when loaded, it really makes no difference if its loaded or not, just let it fly when you charge it.