F-Marked FSB ?

[Neeglik]

Ok, some fill me in with a layman's explanation of the f-marked fsb's. I understand it has to do with mounting rear irons on a flat top, but I'm unclear on how it affects accuracy.

FWIW I have a Bushmaster barrel assembly (with the FSB) that I put together. I've zeroed it and it seems to work just fine. Am I going to see a problem shooting at certain distances or what? What can I do to fix the possible problems I'll face with it?

TIA


ps. I did a search, but came up blank with this particular info...

[Robb Jensen]

The F height FSB is used with flat top ARs. Many times if you don't have a F height FSB when trying to zero the rifle the front sight post will stick way up in the air and be very loose in the FSB. If you don't have a F height FSB you can get a slightly taller front sight post for about $6 from Bushmaster.

http://img.photobucket.com/albums/v408/gotm4/FshelfColt.jpg

[jhs1969]

I had this problem with the last two BM's I've had. The previous is owned by a friend and the last is now my wife's. On both I called and complained to BM and they sent me a taller front sight post at no charge. Give their customer service a call and give it a try:cool:

[lanceriley]

F FSB is 1.98 tall while regular FSB is 1.94 tall.

if you zero your iron sight to 50yards using a std FSB, you will be shooting high or your front sight will be way up. although you can get a taller frontsight, it will be taller than the front sight wings. you don't want that part getting banged.