Ar 15 problem looking for help

[horsemen61]

Hey everyone so a friend of mine bought a Anderson AR 15 a few years back and it was one of those where you had to buy the “ furniture“ separate so he did that and put it away yesterday he asked me to shoot it and I did but I had a problem which is as follows it would fire a round then pickup the next round but wouldn’t fire the second round I thought maybe it had to do with the upper so I switched the upper to my lower and I couldn’t get it to fail so I put my upper on his lower and same thing it puts a very tiny mark on the primer I am thinking it might be a trigger/hammer issue not sure any ideas guys on what you would think would cause this like I said I believe it’s a lower issue so I’m guessing it’s a trigger problem but maybe it’s an buffer/buffer spring issue I’m not sure any thoughts are always welcome thanks for reading

 

[12Bravo20]

The first thing I would look at is to make sure the hammer spring is installed correctly.

 

[powermad]

Just like a TP roll, over the top please.

 

[Varminterror]

Hammer spring in the lower is an easy check.

Check to be sure the rifle is actually closing into battery. The hammer wastes a LOT of power closing the bolt into battery if the action isn’t closing properly.

Check mag drag on the carrier also.

Lubricate the upper, make sure his buffer is free traveling.

 

[horsemen61]

Thanks guys I’ll try all that to start

 

[243winxb]

Hammer following bolt? Trigger pull to light.

 

[horsemen61]

Hammer following bolt? Trigger pull to light.

factory mil spec trigger not aftermarket

 

[bubbatime]

The hammer spring is installed backwards, like said above. Lots of guys do this on home builds. It actually functions most of the time with the spring backwards. I spent a lot of time at the range and every day someone with an AR15 would have the trigger pins or hammer pins start walking out of the lower and it was ALWAYS the hammer spring installed backwards. If you ever see the pins start walking on the lower there is a 99% chance that the hammer spring is installed backwards.