Double fire

[Stu_Padaso]

i have a COLT M-4 carbine , on last three times ive gone to range it will double fire once or twice out of about 100 rds
is this common or should i be worried about a run away AR ?

THANKS

[Doc45]

Yes I would be concerned and have a competent/qualified gunsmith check it out before firing it again.

I saw a Colt Gold Cup do a full auto mag dump on a good friend with the second mag he put in it. Turned out before he got it the sear was modified just a tad too much. Surprised the hell out of both of us.

[Stu_Padaso]

Should i send it back to COLT or is that a waist of time ?

[def90]

Should i send it back to COLT or is that a waist of time ?

If it’s new and under warranty I would send it to them.

[ray1970]

I’d look at it as a good time for a trigger upgrade.

[Great-Kazoo]

trigger reset or weak sear spring. A new drop in unit runs $100 ish take Ray's advice, replace it.

[BPTactical]

Doubling can be a challenge to diagnose, especially an inconsistent problem.
It can be due to hammer follow(typically a disconnector issue) or slam firing.
Clean your trigger group very well, you may have a chunk of primer or other debris floating around preventing the disconnector from traveling freely.
If your budget allows drop a Giesslle in it, you will never regret the investment. If your on a budget the Rock River 2 stage is decent, Timney, McCormick are decent as is the JP trigger system but it requires a bit of work to time the disconnector.
A few things can cause doubling, weak/ broken trigger spring, weak / broken disconnector spring or disconnector, disconnector timing, defective trigger and or hammer (inadequate sear engagement surfaces/angles).
Short of swapping fire control components (hammer, trigger, disconnector and springs) it is not worth attempting any repair of the current items by either you or a 'Smith, the components are cheap enough - just replace them.
Check your bolt, cam pin and firing pin for debris, a burr or such, you don't want the pin sticking and causing a slam fire, potentially a dangerous situation particularly if the bolt is not locked. Just clean the components well and assemble them with no oil, shake the carrier group with the bolt fully extended, the firing pin should move freely and should even rattle a bit.
Again if a component is of question, just replace it.

[BPTactical]

I saw a Colt Gold Cup do a full auto mag dump on a good friend with the second mag he put in it. Turned out before he got it the sear was modified just a tad too much. Surprised the hell out of both of us.

A mag dump on a 1911 will surprise the shit out of you!
Typical culprit on a 1911 mag dump is a short disconnector.
Easy safety check every 1911 owner should know:
With a CLEAR weapon and no magazine pull the trigger so the hammer falls. Keeping the trigger fully depressed retract the slide fully and let it go. Do not ease the slide forward, let it return to battery under the force of the recoil spring.
The hammer must remain in the fully cocked position, even with the trigger pulled. This tells you the disconnector is functioning correctly and sear engagement is adequate.
Hammer follow is bad on any firearm but on a 1911 it can be disastrous.
This test is a MUST for anyone inspecting a used 1911. Just be courteous to the owner and tell them you would like to perform this test prior to doing it.
Letting a slide slam closed on an empty chamber on a 1911 is bad JuJu and a poor practice, it causes the sear nose to bounce against the hammer and can destroy a nice trigger job if done enough.
Unfortunately to check for proper disconnector function / sear engagement it is a necessary evil.

[brutal]

I think there have been many of those FA 1911 jobs done by a certain "smith" down in the Springs...

[Irving]

A mag dump on a 1911 will surprise the shit out of you!
Typical culprit on a 1911 mag dump is a short disconnector.
Easy safety check every 1911 owner should know:
With a CLEAR weapon and no magazine pull the trigger so the hammer falls. Keeping the trigger fully depressed retract the slide fully and let it go. Do not ease the slide forward, let it return to battery under the force of the recoil spring.
The hammer must remain in the fully cocked position, even with the trigger pulled. This tells you the disconnector is functioning correctly and sear engagement is adequate.
Hammer follow is bad on any firearm but on a 1911 it can be disastrous.
This test is a MUST for anyone inspecting a used 1911. Just be courteous to the owner and tell them you would like to perform this test prior to doing it.
Letting a slide slam closed on an empty chamber on a 1911 is bad JuJu and a poor practice, it causes the sear nose to bounce against the hammer and can destroy a nice trigger job if done enough.
Unfortunately to check for proper disconnector function / sear engagement it is a necessary evil.

Will this test still work if you load a few dummy rounds into an empty mag, or must the magazine be clear of the gun?