I wanted to start a discussion about the very early 601 FCG. There is something totally different about them. Is it the quality of workmanship during that time period. When I shoot a AR with a nuetered 601 FCG I am noticeably more accurate. The pull is smooth and the break is great. It is just better. I do notice the disconnector is shaped differently. I can still shoot pretty good last month I shot 39/40 with a raggedy FN A2 for Army qualification.



Late 70s M16 FCG moded to semi automatic spec. Notice the difference in the shape of the disconector.  

I've noticed they are generally better also and make a decent foundation for a very good single stage FCG if one doesn't mind actually using the rare pieces.  Probably quality control that hadn't been corner cut to death since it's introduction for reasoning.  Current production S in square for coins is probably the best readily available today until one steps up to aftermarket.  The dot marked stuff pretty much blows and most should be ashamed to even call those American manufactured from the few I've actually used.

Looking back I probably regret neutering the 01 units although my justification was nothing spent vs spending a few coins,  resources and the time factor.  It's what I had on hand to complete a build.  Hindsight I should have sold the 01 pieces and not neuter them or simply bought something better with sales profits but my decision to put something together immediately and shoot it outweighed the better judgement call of wait and purchase an aftermaket or not use a fairly rare FCG.  I also prefer a modified single stage over a two stage in most shooting applications.  Possibly if I had been brought up on Geisselle or such I would have a different opinion.

Good to better shooters can generally make most anything work with better than decent results without breaking the bank also.  Hence the 39/40 score with a well worn nothing special weapon.  Nice shooting.

Thanks figured I'd have to do OK since I'm retiring next month after 23 years of service.  Maybe the last time I ever shoot another real M16!

Well shoot some m16s!

My question is why did you alter it? I NEVER use the disconnector from a FA kit in my retro builds. But I still have it. its the only piece that can possibly cause it to multi fire on a single trigger pull short of a general trigger failure.  All my retros you open up are not milled to accept a sear and all have the tip on the hammer still to better preserve the authenticity of the rebuild with period correct parts.

Just curious if you know something I don't, or haven't heard yet?

It will never be in a 601 again, as well as its legal to use when modified. I like the way it shoots so I just did what I wanted with it. It is never going to be for sale. Also to note that modified FCG is not a 601 version. The two pics are there to show the difference in the disconector.

I used unmodified M16 FCG, except for a semi auto disconnector on my retro builds.  Much smoother than the aftermarket ones in my modern builds.

I might add, that this three shot, one hole 25 yard group was with an AR15Sport.com 1/9 pencil barrel and a Colt M16 Hammer and trigger in my 604 (turning into 602 build now).  Ammo was Federal/Lake City M193.

Good shooting Bernie, I put 5 in one hole at 25 yards with my XM16E1 with moded 601 FCG. Same 55 grain federal ammo.

I just cut the shark fin off the selector. Without an autosear the hammer hook is harmless. If there is no hole for the sear it wont fit. Case point

ANd they are made different. You would think the best aftermarket is BCM parts and the colt stuff is way smoother than BCM.

Yeah, but it is SO HARD (mentally) to cut the shark fin off of a nice dimpled selector!

The first time is the worst, done it twice lol.

This!  It is easier to use a semi disconnector!  Argh!  I just can't murder an M16 FCG!  It is sacrilegious blasphemy and heresy!

I agree - I think the disconnector is the key. The trigger in my 604 had a neutered M16 disconnector, and it was one of the best stock triggers I've ever felt on an AR.