A2 and A4 carry handle sight guts compatibility, and .170 FCG question

**masakari** · 05-17-18, 18:01

So, I'm building an A2 "clone", except that I'm making it how I think it should have been. That means lightweight barrel and A1 length CS stock.

Anyway, one of the things I'm considering is using A4 sight guts (6/3 0-600 yards) instead of the optimistic A2 (8/3 0-800 yards) sights.
I currently have a Colt A2 upper, and will be getting a Colt A4 carry handle.
Will I be able to swap the sights themselves between the two? Are they compatible?

Also, my lower happens to be an old Colt .170" FCG large pin lower, and the hammer is notched. Does anyone still sell a rounded (not notched) .170" Hammer?

Thanks guys

**markm** · 05-17-18, 18:23

Why are you worried about the Type 2 hammer? Is it a functional thing? Or authentic appearance? As long as you have a real 16 carrier, the Type 2 hammer will be fine.

**masakari** · 05-17-18, 18:31

Originally Posted by markm

Why are you worried about the Type 2 hammer? Is it a functional thing? Or authentic appearance? As long as you have a real 16 carrier, the Type 2 hammer will be fine.

Not worried, I just don't like notched hammers. They feel gritty when cycling the bolt, and remind me of the evil black rifle ban of '94. So I just prefer standard rounded hammers whenever possible.
And yes, I am using a standard M16 carrier.
I had an ALG QMS set aside for this build, until I got the lower and discovered later that it was a large pin... Go figure.

**sinister** · 05-17-18, 19:42

If you want to use the A2 sight in an A4 handle you have to mill a hole in the upper. The A2 sight stem is longer.

I've shot the M16A2 out to 1,000-yards -- which is why I went to M14s and bolt guns for farther out.

I replaced all my fixed rifle stocks with A1s -- perfect length for me.

Geissele makes a large-hole 2-stage trigger. Not sure if anyone still carries large-pin hammers for Colts.

**Stickman** · 05-17-18, 20:07

Originally Posted by sinister

If you want to use the A2 sight in an A4 handle you have to mill a hole in the upper. The A2 sight stem is longer.

Awesome memory, this isn't a question which comes up often at all.

IIRC, this used to be a test question in the Colt armorer course.

**masakari** · 05-17-18, 20:26

Originally Posted by sinister

If you want to use the A2 sight in an A4 handle you have to mill a hole in the upper. The A2 sight stem is longer.

I've shot the M16A2 out to 1,000-yards -- which is why I went to M14s and bolt guns for farther out.

I replaced all my fixed rifle stocks with A1s -- perfect length for me.

Geissele makes a large-hole 2-stage trigger. Not sure if anyone still carries large-pin hammers for Colts.

Thank you very much for the info and picture.
So I definitely won't be doing that with the carry handle, but would still consider doing the other way around and putting the 6/3 guts into the A2 upper. Think that would work well?
I can't see myself shooting any farther than 500-600 with iron sights... Can barely even see the target!
With an ACOG I've shot out to 800, however, with great success.

As far as the trigger, geissele does indeed make one... It's a little pricier than I'm willing to spend right now, however.