Recap:  Had my chamber recut from .223 to 5.56NATO, now the rifle is trigger slapping like crazy (with occasional double fires in my previous trip to the range).  Checked the FCG, and found a broken trigger pin.

I took my rifle out today after replacing the trigger pin.  The trigger is still slapping like crazy...so hard that it is painful to shoot.  I fired ~30 rounds of various ammo thru various mags and called it quits.  

I came home and pulled the FCG again...found the trigger pin with a noticeable bend in the center.  No other defects/problems noted with the FCG or springs.

So...again my question is...could the headspacing have changed when the chamber was recut...enough to cause this issue?  This rifle ran fine with Winchester White Box (~1500 rounds thru it) before the chamber was cut so that I could run milsurp ammo.

Thanks guys...

I know of no way it could cause it. I bought a reamer and did a few of mine have no problems and did not expect to.

What  fire control parts are you using and are you sure they are functioning and assembled correctly?

This won't help.....
But why would you have a barrel reamed from .223 to 5.56????  

I would contact Randall at ar15barrels.com on this one.

Edwin...did it because milsurp ammo is cheaper and more plentiful than .223 ammo.  And its not necessarily safe to shoot 5.56Nato ammo in a .223 chamber.

Yes...FCG is assembled correctly.  Can't remember the source of the parts kit...i put the rifle together ~5 years ago.  But the rifle was functioning fine until reaming it, but the feedback seems to be consistent that this could not cause the trigger slap.  I am really baffled at this point...

only way I can see the FCG bending/breaking the trigger pin is the hammer is moving too far when the bolt carrier cycles?weak hammer spring perhaps? or the gas system is WAY overkill now(no idea how)?


are there any marks on the top of the tail of the disconnector where the hammer would hit?

yes...there is a shiny spot on the tail of the hammer and the top of the disconnector...lbut it ooks like it has been doing this awhile.  Could the NATO-spec ammo be so much more powerful than Q3131A that it is causing this trigger slap?

I was getting trigger slap with Win WhtBox yesterday...but that was with a broken trigger pin.  Did not have anymore .223 today after replacing the pin...had to do the test with Radway Green and Adcom surplus ammo.

Who made the lower?  Only thing I could think of is the pin holes are out of spec or you have a bad FCG that needs replacing.  Maybe either of those problems werent appearent until you started using 5.56 spec ammo.

If the hammer is hitting the disconnector grind the back hook down until it does not hit anymore. About .050 should be enough. If not enough take more off. It won't hurt a thing but should solve the problem.

Off subject: only 1500 rounds in 5 years?

Dude, You need to get out to the range more!

I blasted over 4k this past year, & I'm a cheap Bastard!

On subject: I can't for the Life of Me figure-out why re-chambering to 5.56 NATO would cause such a strange problem. Good luck Bro, & +1 on Randall figuring this out for You. He really seems to know His stuff.

The Ol'Crew Chief

Its a Bushmaster lower...pretty sure its in spec.  

Haha.  Sad but true C130Montana...I shoot a lot of .308 thru my FAL and HK91, but alas...coaching kids baseball take priority so trips to the range are few and far between.

ps  assuming you are a Guardsman?  I was a WC-130 Nav back in the late 80's...

does it do the same with a different upper , still chambered in 5.56 NATO and with the same ammo?

To 66Bushman:
I was a Flyin' CC out of Dyess AFB 82-86. A part timer in MT ANG 86-96.
The C-130 is the Finest Flying Machine EVER!!!
I miss it so bad.
My Life would be MUCH better if I could just take a simple flight around the flagpole about once a year or so.

I close My eyes & I can still smell the inside of a Trash Hauler...
Best days of My Life!


The (Melancholy) Ol' Crew Chief

dave...when we swapped my buds Rock River lower...there was some trigger slap, buit not as noticeable.  His upper on my lower seemed to work fine...

Quoted: dave...when we swapped my buds Rock River lower...there was some trigger slap, buit not as noticeable.  His upper on my lower seemed to work fine...

I would pretty  much say that means you need a new barrel


did they do anything to the gas port when they rechambered it?

Quoted: To 66Bushman: I was a Flyin' CC out of Dyess AFB 82-86. A part timer in MT ANG 86-96. The C-130 is the Finest Flying Machine EVER!!! I miss it so bad. My Life would be MUCH better if I could just take a simple flight around the flagpole about once a year or so. I close My eyes & I can still smell the inside of a Trash Hauler... Best days of My Life! The (Melancholy) Ol' Crew Chief

Some of us who didn't fly on the job miss the Herc too.  I spent a total of 10 years at Keesler, and I can still tell when a Herc is running right or not just by the sound (I can't tell you what's wrong, but when a Herc makes the wrong sound, it really stands out!)  I did one IG tour to Little Rock too, and we flew their aircraft to and from.  Lots of memories in those things!

No...as far as I know, they just did a simple ream of the chamber...