First off, thanks for looking

I'd like to clean up the gritty trigger on my new Colt M4 carbine. My other ARs have had gunsmith trigger jobs-but I'm not looking for that kind of perfection with this one.

Basically I'd like to to remove the hammer, trigger, sear, and disco to clean them up and then reinstall them.

It looks deceptively easy-just punch out the pins, do the deed-and then put them back together.

There must be more to it than that though, right?

Thanks in advance for your expertise!

It’s pretty simple.

However, if you’ve got a digital camera and you’re as forgetful as I am, you might want to take a couple of shots of the inside first just as a reminder of what it’s supposed to look like after you’ve reassembled it.  [:D]

Alternatively, make a quick drawing.

IIRC, you’ll also need to remove the selector (safety) switch.  To do this you’ll need to first remove the grip to release the selector detent and spring.

Anyway, go here to download Army TM 9-1005-319-23:  [url]www.ar15.com/content/books/[/url]

This is the army’s armorer’s manual and is quite long.  Note that it’s for a M-16, not an AR-15, so there’ll be some differences in the fire control parts.   Frankly, it’s not terribly clear.  What you’re looking for is (I think) in the vicinity of pages 3-65, 3-76 and thereabouts.

Good luck!  

Thank you!! [:)]

I'm downloading it now, and will take some pictures momentarily.

CJan_NH,

We must quit meeting like this people are beginning to talk.

Anyway,

You shouldn't have to remove your selector to remove the FCG. Some clone guns are made quite right and you have to remove the selector so that the trigger can be removed. You have a Colt so that won't be a concern. [^]

With the hammer forward (safety on SEMI obviously) push out the hammer pin. It helps to push the pin so that the outside most annular groove does NOT slide through the hammer on its way out of the lower. I use a 3/32 pin punch, you can use whatever you want. Just make sure you get the head of the pin subbed beneath the surface of the lower before pushing hard on the head of the pin. That will keep the tool from slipping and scratching the area around the pin hole.

With the hammer removed, slowly push the trigger pin halfway out while restraining the disco. You can make this part easier if you gently push down on the top of the disco. If you don't restrain the disco, it'll launch. Push the pin so that the outside annular groove goes out of the lower without passing through the trigger. Once you have removed the disco completely remove the pin and then remove the trigger. You're done.

Three biggest mistakes in reassembling (as you said, taking it apart is too easy) the FCG, in order, are as follows;

Failure to properly install the hammer spring onto the hammer.

Failure to place hammer spring legs on top of trigger pin.

Failure to properly install trigger spring on trigger.

Pay attention to how those parts fit together while you're pulling them out of your lower.

When reinstalling the pins push the end of the pins [b]without[/b] the annular groove into the lower first. That way the J spring in the hammer won't grab the outside groove and the disco won't do likewise.

Make sure that the hammer spring leg sets down into the outside annular groove on the trigger pin.

Make sure that the nose of the trigger spring is under the sear face of the trigger.

Make sure that the legs of the trigger spring do not get caught in the hole for the trigger while you're reinstalling the trigger.

Make sure that the large end of the disco spring winds up pushed into the trigger.

I hate to point this out bud but if you don't know how to take it apart or put it together what are you doing messing with it? [>:/]

Once it's back together perform a funx check per the -10.

Thank you Tweak. I wish I had seen this post before I tore it apart-reassembly would have been easier. I reinserted the pins with the annular groove end first, and subsequently got one of them hung up on the J spring.

I agree that I probably shouldn't have messed around with it in the first place, but I am trying to learn to be more self-sufficient with my ARs. For years I have had no fear whatsoever about tearing down one of my HK USPs or Benelli shotguns, but I was always afraid of screwing aound with the ARs. Now that I've got the lower figured out I'll feel much better about having to replace parts when the need arises.

My two preban Colt 6601 HBARs have over 10k rounds apiece through them, but so far the only thing I've ever had to replace was an extractor spring that went TU on one of them. At some point something is going to break, and I'd like to know how to fix it [:)]

I have a small mountain of spare parts, including three complete sets of .170 FCG parts and three complete bolts/carriers but aside from the extractor spring I've never had to replace anything.

One of these days I'll pick your brain about gas tube replacement, because the procedure for getting the gas tube free from the FSB is a mystery to me. Someone here told me once that the gas tube wears at the carrier key and occasionally has to be replaced, so I'd like to know how to properly complete that repair too.

I'd also like to know how to properly rebarrel an headspace an upper. Now that I've dug into a lower I feel the need to build my own AR from a parts kit.

Thanks again for your detailed procedure. I am going to plagiarize the hell out of it and refer to it the next time I feel the need to play "kitchen table gunsmith".

Edit: Just found the FAQ in the other forum and learned about headspacing. Now all I need is a set of go/no-go/field gauges.

It won't happen again, call it a teaching moment. [:D]



Admirable, at least you hang out here so your chances of making a horrible mistake are lessened.



Ah, hence your lack of troubleshooting and repair experience. Nice thing about having two is you can fiddle with one and use the other as an exemplar.



You're about halfway to the breaking things point, 25K for the bolt, only thing allowed to go down before 6K rounds is the ext and eje springs, and even those are only allowed if they happen on less than %50 of the rifles tested.



Simple matter of driving out a roll pin, pulling out the gas tube, inserting the new tube and pin and checking function.




It's true, one of two parts [b]designed[/b] to wear out on the AR. Cheap, simple parts that are easily replaceable.



That's a whole nuther box of cat litter.



Feel free to, unlike some I don't demand credit for knowledge. After all, I learned it from someone else too.



[url=http://ar15.com/forums/forum.html?b=3&f=66]This[/url] forum? Save that link, you'll prolly be needing it if you build an AR from the ground up. Unless you can find a Colt kit. [+]:D]


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