# AR-15 problem, Who has advice?



## Helmet_S (Mar 18, 2010)

I just finished my first AR-15 and shot it today for the first time. It shot great but only as a single shot.

It shoots the first round fine and it loads the next round into the chamber fine also. When you pull the trigger the hammer isn't cocked. When you pull back the charging handle to cycle in a new round and cock the hammer the unfired shell has a mark in the primer from the firing pin hitting it.

I think that the hammer isn't getting fully cocked and when the bolt carrier actions forward the hammer follows and hits the firing pin which in turn strikes the primer. It is just a bit short of firing the fresh round and I am afraid that if it does it will be caught in a full auto cycle until the clip is empty.

The only other option that I can think of is that the bolt carrier group is hitting forward so hard that the firing pin is stricking the new shell but that wouldn't explain why the hammer isn't cocked.

Any advice would be greatly appreciated. I am going to break the rifle down and ensure for about the 10th time that everything is there and installed correctly.

Let me know guys. I will post when we find the correct problem so that we all know and it can help others in the future.


----------



## catcapper (Feb 11, 2010)

Sounds like your disconnector isn't catching the hammer and letting it follow the bolt forward.

The firing pin mark on the primer is normal with all AR's.

Check to make sure the gas tube is clear too.


----------



## knapper (Feb 5, 2010)

I have read some in the manual for the AR and it may mean that the powder charge is not getting the pressure high enough to get the bolt all of the way back. Also they say in the manual unless I read it wrong is the bolt assembly needs to be lubed so the bolt, firing pin and everything else needs lubed, I found out that one in a match when one of mine quite working properly. There is another problem is the bolt is not going to full forward. Which would give a hammer drop and not make contact with the firing pin.


----------



## bar-d (Feb 3, 2010)

Helmet, I would suggest pulling the bcg and completely take the bolt apart. Pull the firing pin and bolt rotator and make sure there are not burrs or rough places on any surface. Clean and lube everything, reassemble and hand cycle the charging handle until you think your arm is going to fall off. After building two ars this past year, I have found there are usually gremlins in them until they are fired enough to mate all the parts and function correctly.


----------



## Helmet_S (Mar 18, 2010)

Thank you for the advice guys.

Upon doing a little research today online (I am at work so I have time) here is what I have found.

It looks like the problem is with the disconnect spring. I have found out that a weak, broken, or non-existant disconnector spring will cause this same issue exactly. I have read that a non-existant disconnector spring would cause the rifle to fire full auto until the clip is empty. a weak or broken spring would cause the trigger to not reset and leave a nice dimple in the primer.

AR-15's are prone to leaving dimples in the primer of the next cartridge but they should be light and no where near like what I am seeing. Basically if the disconnector spring is bad and not resetting the trigger then the hammer is just continously follows the bolt carrier back up and if the spring wasn't there at all would possibly just keep firing the next shell.

I located a new spring at a local shop here and will pick that up on the way home. hopefully that will fix it. I probably won't know until this weekend when I would be able to test it again.


----------



## bar-d (Feb 3, 2010)

Hope that fixes the problem. I know what it is like to have a 1000 dollar semi automatic single shot.


----------



## Helmet_S (Mar 18, 2010)

Well I haven't gotten to shoot it yet but I did replace the spring. I tore down the lower lastnigt and took out the other disconnector spring. I compared it to the new one with just my fingers and could feel a huge difference in the tension of each spring. the newer one was alot stiffer than the old one. I would think that this will fix it. if it doesn't then I will be on the seach again. I will post on how it shoots when I make it out and try to post a target so that you can see how it shoots also.


----------

