F marked or non f mark for a1 carry handle upper with carbine length gas system?

[URGILOVERR]

I’m not seeing a whole lot of non-F marked front sight base options I’m building out a XM 177E2 and I was wondering if I could use a F marked front sight base with my a1 carry handle upper with an a1 rear aperture sight system. I’m seeing all different types of replies on other threads can somebody school me on this ? Can somebody just tell me the type of front sight base and front sight post (a1 or a2 fsp) I can use with an a1 carry handle upper carbine length system with a1 rear sight?

 

[the_assman]

i believe you would want a non f marked fsb for an a1 upper

the f marked fsb will work if your not trying to be clone correct

you might possibly need a taller front sight with the f marked fsb and a1 upper

i've built a few a1 uppers with f marked fsb's and they zero'd out fine without a taller front post

 

[Skunkworx]

Yea you can use an f height fsb on an a1 upper if you’re cool with shortening your front sight post. I had to bottom mine out completely to get a 36yd zero. They do sell shorter front sight posts or you can just file yours down like .040 to get your normal range of adjustment back.

 

[URGILOVERR]

Yea you can use an f height fsb on an a1 upper if you’re cool with shortening your front sight post. I had to bottom mine out completely to get a 36yd zero. They do sell shorter front sight posts or you can just file yours down like .040 to get your normal range of adjustment back.

I’ll just do that, can’t find any colt non f marked virgin (non drilled and reamed) front sight bases and I Don’t know who makes the unbranded ones, I’ll just cop a BCM F marked and file down with a fine smooth cut file, and apply cold blue as needed if I can’t find any shorter front sight post.