I am getting stuff together for a build.

I just got my M4 (14.5") barrel assembly and saw it did not have an F-marked front sight base.  I know this will be a problem as I will roll with a flat top upper and BUIS's.  

The other problem is I'll have to get a phantom permanently attached to the barrel to get over 16 inches.  So I need to figure out my options now rather than after I've gotten the FH welded on.


So, can I get a NM front sight (I need a narrower front sight than the standard width) that is the .04inches taller than normal?

If not, where can I get an F-marked FSB that I can install on my bushy M4 barrel before I send it to ADCO?



Thanks!

If you're going to send it to ADCO, contact Dave (PropDoc) and ask him - they may be able to supply the parts.

I called Bushmaster and complained that there short one wasnt matching up with my A2 carry handle, which is was not and they sent me the .40 taller one free, no questions asked.

The Bushy I got was a flat top and did not come with a carry handle. The one I bought didnt line up right.

+1

Bushie, and several other commercial suppliers, build their rear sight assys with an .04 inch lower sight unit, so they can get away with not using the .04 inch higher front piece. If, however, you install a Colt or other milspec height unit, you're going to need a higher front sight point if you don't have an F base unit.

Actually, the higher front blade is a better solution to the problem than the F base, in my opinion. With the F base, you use a blade that is too wide for ideal aimpoint on a carbine. The higher carbine blade comes narrower than the standard rifle blade. Always has––-right from when Colt started building carbines and SMGs back inthe 1960s.

The F base only came along when the Army adopted the M4 as the standard issue piece, and that was so unit armorers wouldn't have to keep two different height blades in stock, and risk putting the wrong blade onto a piece that was in for refinishing or front end work.

I believe DPMS and RRA and M1S all sell the extended front sight posts.

So where can I get an F marked FSB for my bushmaster barrel?

It looks like all the national match (thinner posts) aren't the taller type.  But if you know of NM front sights that are taller please let me know.


Thanks

I agree with the "too wide" part, in fact that's why I want a narrow National match front sight on my carbine (when it's built).

Aren't most all of the BUIS's and Carry handles the "milspec height"?
The reason I ask is if I'm not going to be able to find a narrow .040" taller front sight, I'm going to have to put an F marked Base on.    I really wish these companies would plan ahead.

Idon't know where you're looking but Bushmaster, DPMS, and yes, even Colt, sell an .04 inch higher front blade that's narrowed to give a "normal" width sight picture on the carbine.

I don't know which aftermarket back up sights are milspec and which are lower.  My own research was confined to the full length clamp on aftermarket pieces. I can tell you that Colt is, of course milspec height, whils Bushmaster, DPMS, Rock River are all built with an .04 inch lower rear sight unit, so thary don't need an F base or higher blade when they build a flat top carbine.

To add insult to injury, the damn DPMS rears have 1 minute elevation adjustments, but use the 1/2 minute elevation scale, which makes the distance markings on the sight absolutely useless.

I see where many of the "tall" front sight posts are listed.  

However I want a "tall" sight that is the national match width of .05 or .052 inches.

You could probably get a regular extended front sight pin and take a dremmel to it and thin it down, then spray it with some high heat engine paint. Just make sure to tape off the threads real well.

Eh...I'm not feeling that so much.  I'm betting I could have ADCO, or a decent machinist with a mill cut each of the 4 sides of the post down, then I could refinish it.


I'm still looking for an F-marked FSB, I think I'll go that route since most BUIS's are "mil-spec length".

Undrilled F marked FSB

Thanks, I saw it but didn't think that Bravo had them in stock.   I'd have to get a smith to do that though.