Colt SP1 carbine FCG question

[MSW]

I have a 1982 Colt SP1 carbine that I bought lightly used from the original owner who claimed less than 1k rounds. I’m told it was 100% original, sighted in with unknown .223 & placed in a safe until I bought it (I paid too much, which isn’t germane). I’ve shot it twice, and both times the trigger pin walked out the left (side where the bolt release is located) & the gun jammed due to the trigger not engaging the hammer properly. The FCG pin holes don’t look “egged” oval or irregularly worn. When the first malfunction occurred, I figured the hammer spring legs weren’t in the groove of the trigger pin properly. But the second time, I know the parts (spring legs) were aligned, but it happened again shooting XM193, by the 3rd 20 round mag.

My inclination is to replace the FCG pins & springs, but in checking the brass, there’s extracor smears & burrs, which I think are from the extractor as the burr is on the front of the rim. So, now I wonder if the semi auto BCG is too light & I should add a FA BCG +/- H buffer, or perhaps this is a separate issue.

Sorry, but I didn’t think to take picks before I put the brass into the reloading box (which is mostly DD brass) nor did I think to take a pic of the drifted pins, as I just wanted to fix it due to concern I purchased a damaged/defective carbine.

Any suggestions on how I should proceed?

Thank you.

[mark5pt56]

I would replace the hammer/trigger and disconnector springs and see what shakes out before monkeying with other things. Check free length of the action spring. Take a look at the extractor to see if there are any burrs on it, also pull it to see if he has added anything in there like a donut.

[MSW]

I don’t mean to sound like a dumbass—but does replacing springs detract from value? I have Wolff hammer springs, not Colt.

[MistWolf]

I don't think replacing the springs will hurt the value of your SP1. Even if it did, the malfunction will hurt the value even more.

I would definitely try an H or H2 buffer and a new action spring in your carbine.

[MSW]

What about the BCG? Leave as factory semi or put in the FA version? I already dug out a Colt (I prefer BCM, but it seemed sacrilegious when I had a Colt) and replaced it, but am curious to know a more,experienced opinion?

[MistWolf]

If the factory BCG is an unshrouded semi-auto carrier, I'd get a full auto carrier. Unshrouded carriers cock the hammer with the firing pin. That's hard on the firing pin.

Yeah, I'd put a Colt carrier in there. A BCM carrier would work fine, but you don't put a Chevy engine in a Ford

[MSW]

Thank you all for your help.

Ford & Chevy? Next thing someone will put a Colt Python barrel on Smith & Wesson.

[scottryan]

Are you sure the FCG is even the factory parts this gun came with? A factory assembled FCG cannot have a pin walk out.

The first thing I would do is remove the entire FCG and post pictures of it here.

You need to update the hammer to a full round colt hammer if not already present. SAW sells these. Also upgrade the carrier to a full auto carrier colt carrier.

[MSW]

Yes, I’m as sure as I can be that the hammer & trigger are Colt as they have the ‘C’ in a circle, like my other Colt parts. So I’m fairly sure they’re Colt. If not, they went through a great deal of trouble to make copies. I was taught in an AR armorer course (not Colt, it was a local cop with connections to Bushmaster) exactly what you said about the springs aligning in the respective pins & grooves and was taught the aftermarket retainers for full auto (anti-walk pins) weren’t needed. My first thought was the hammer spring wasn’t installed properly or was bent, but it looked fine.

I’ve only been shooting ARs (Bushie) maybe 20 years, and Colts only the past 10-ish years, which is why I'm asking for advice. This site was my education about better quality ARs & my “AR course” had volumes of missing information.

Will work on pics.

Thank you again.

[MSW]

Yes, I’m as sure as I can be that the hammer & trigger are Colt as they have the ‘C’ in a circle, like my other Colt parts. So I’m fairly sure they’re Colt. If not, they went through a great deal of trouble to make copies. I was taught in an AR armorer course (not Colt, it was a local cop with connections to Bushmaster) exactly what you said about the springs aligning in the respective pins & grooves and was taught the aftermarket retainers for full auto (anti-walk pins) weren’t needed. My first thought was the hammer spring wasn’t installed properly or was bent, but it looked fine.

I’ve only been shooting ARs (Bushie) maybe 20 years, and Colts only the past 10-ish years, which is why I'm asking for advice. This site was my education about better quality ARs & my “AR course” had volumes of missing information.

Will work on pics.

Thank you again.

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