Front sight confusion

[TN cop]

I just bought an ArmaLite 5A4CBA2. It's a 16" middy that has a A2 FSB instead of a "F" marked FSB (I think). I want to remove the carry handle and install either a TROY or ARMS #40L SP rear folding sight. What height are these sights built to match....A2 or "F" marked. Will I encounter problems while zeroing either of these sights with a non "F" marked FSB. I've read controdictory info regarding a non "F" marked FSB and want to make sure that I have a correct understanding. My current understanding is that the difference between the A2 and "F" FSB is the height of the shelf and can be corrected (if need be) by buying a taller front sight post (that will be protected as the A2 FSB has taller ears than the "F" marked).

Not trying to beat a dead horse, this is my 1st AR and will be used for patrol work...so my life may well depend on doing things right the first time.

Thanks in advance to all thos in the know that will help a FNG like myself!

[Robb Jensen]

You will very likely need a Bushmaster .040" taller front sight post. A non F marked FSB is a little taller, if used with a flat top receiver it usually puts the front sight too low thus causing sighting in problems. The Bushmaster taller front sight post retails for less than $6.00

[TN cop]

I spoke with one of my dept's armorers (ex-military armorer as well) about this and he looked at me as if I was crazy :confused: . So to confirm, if I use a TROY or ARMS #40L SP rear folding sight and not the detachable carry handle that came with my rifle.....I will need to use the Bushmaster .040" taller front sight post. Don't mean to be redundant, but he acted like I made the whole "F" marked and A2 FSB thing up.

Thanks again!!

[Robb Jensen]

I spoke with one of my dept's armorers (ex-military armorer as well) about this and he looked at me as if I was crazy :confused: . So to confirm, if I use a TROY or ARMS #40L SP rear folding sight and not the detachable carry handle that came with my rifle.....I will need to use the Bushmaster .040" taller front sight post. Don't mean to be redundant, but he acted like I made the whole "F" marked and A2 FSB thing up.

Thanks again!!

Yes. If he doesn't believe you ask him to call Colt.

[ErnieB]

Try it out before you spend the $$. I have a Armalite middy w/o issue using KAC & GG&G back up sights.

But piles of BM shorties needed them.....

And, most "armorers" are parts replacement types, not familiar with the range of prodcut in the open market.


Should the sight heights be dialed in if you are using a set of Troy flip ups?

[Harv]

Try Dano's advice first..

I had a Bushy with a Non F marked FSB and was able to zero it with a ARMS 40 BUIS. The front sight had to be spun up a little higher then normal, but not so much that I needed the .040 higher front sight. I did have one at the time, but eventually gave it to a friend. Now I don;t mess with anything other then a F marked FSB....;)

Some guys can get a decent zero without the taller front sight.. and some cannot without the front sight post being spun way up to the point that you get a little wobble..

You just have to try it..

and as for this..


I spoke with one of my dept's armorers (ex-military armorer as well) about this and he looked at me as if I was crazy

That just goes to show you .. that being a Mil Armorer makes you no more of a small arms expert then me living next to the airport makes me a pilot...

Every 19 yr old SPC who works in the Arms room likes to think of themselves as Larry Vickers ;) Truth be told.. you could fill volumes on what they don't know..

Every Armorer I ever knew was a glorified Tool crib attendant who checked arms in and out. filled out the reams of paper work and installed the occasional pistol grip or RAS. It's not like these guys have the training or the equipment to (or the authority) to do anything other then 20 level maint ( a trained Monkey can do 20 level).

That's just my experience over the course of 21 years...

[TN cop]

I appreciate all of you guys advice. I think I'll go ahead and buy a .40 BM front sight post when I decide which rear flip sight I'm gonna go with. I'll try to zero w/o it first and if need be I'll have it if I need it......cheap insurance for $5.

Thanks for the all the help.