AR Pistol Issue

[tattoocarl69]

I set up a 10.5" AR pistol recently (5.56/.223) as an 80% build (this is not my first 80%), with a factory upper and upon testing it, I got about 20 rounds through it before I started getting light primer strikes (light enough to see a faint mark, but not strong enough to even hear any click of the trigger/hammer) with every round the gun would chamber. It shoots the first shot that I manually chamber with the charging handle or bolt release, but every subsequent shot has the aforementioned issue. Here are the things I've tried:
- Complete de-lubing and light lubing.
- Different BCG.
- Holding the bolt catch release down while shooting (this was an issue on a previous build that necessitated the slight filing-down of the catch).
- Using the forward-assist button.
- Different types of ammo.
^^^All of these have had ZERO effect on the issue in question. Again, if I manually cycle the BCG, that round will fire without issue. So, overall, when it cycles, it will successfully load a new round and eject the old one, but the new chambered round will receive a light primer strike and will not be set off.

Has anyone encountered a similar issue? From those I've talked with already it sounds like either a hammer/hammer spring issue or a gas issue. How do I go about troubleshooting this more?

You mentioned it was a plastic lower. Is the hammer plastic also? If so, you may need to file the sides of it down a little. I've had problems with this in the past.

 

[oli700]

You mentioned it was a plastic lower. Is the hammer plastic also? If so, you may need to file the sides of it down a little. I've had problems with this in the past.

had problems with plastic hammers in the past have ya ?

 

[Capn Jack]

That and rubber nails were all my Dad would give me...

 

[oli700]

i don't think that cool stuff has made it this far west yet.....cant wait for the plastic hammers......super fast lock time they say

 

[IronMonster]

Plastic hammer? Well, I've heard of rubber biscuits and lead balloons but not plastic hammers.

I must be getting old and out of the loop.

 

[jbett98]

Plastic hammers are for special plastic ammo.
They're used when you need to get through airport security, as they don't show up on the scanners.

 

[rick benjamin]

Ironbar's thread on "trigger won't reset"
Bolus post #3 shared a youtube that pointed at the "burr"

 

[oli700]

its just good to get new

If the burr developed then it was not hardened properly and will keep developing the burr, as you correct the burr the surface just get further and further out of spec

I have also had one do it that never got a burr, just lost material along the way.

fire control groups are cheap, just cut to the chase and move on

 

[Medic!]

I don't know of any plastic hammer used on AR guns.

But my PS-90 has one. So who knows?