Hello.  Which front sight assemblies (PRI, GG&G, etc.) can be used with the ARMS#40 rear sight without having to use the taller front sight post?  I really need help with this.  Thanks in advance.

Thanks for the replies.

I'm not 100% sure about this but I'll try to help.

If your upper is in spec they will all work with the Arms40

It's when your Flat top is taller than spec that you need the taller sight post.

The taller upper moves the 40 up so you also need to move up your front post.

Bushmaster came to market with the V-match before Colt's mill speced their flat top.  

I could be wrong but that's what I think.

It has nothing to do with the height of the flat top.  It has to do with the height of the front sight.  Only Colt uses a taller front sight on carbine length barrels.  Everyone else uses rifle height front sights.  If you dont have a Colt and you do have a carbine you need a taller front sight.  If you get a tritium front sight it will be tall enough.  Replacement front sight posts can be had from Bushmaster for a small fee.

Thanks for responding.  I still have a couple of questions however.  Okay, I have a Bushmaster flat-top upper with the ARMS #40 rear sight.  My front sight is the BMAS front flip sight.  Does anyone know if I need to use the taller sight post with the ARMS#40?  I would rather not have to use the taller sight post as I like using a much thinner sight post for longer range, more accurate shooting.  What front sight assemblies (either stationary or flip sights) can be used with the ARMS 40 WITHOUT using the taller front sight post?  Thanks again.

To clarify...

When you say Colt carbines have a taller front sight, do you mean just the sight post or do you mean the whole front sight, post, tower, et al?

spacemenow1, if you currently have that set up why don't you just try it out. I put a Swan sleeve (similar to 40 with rail) on a bushmaster upper and I did not need to change out the front sight post. Give it a try and go from there.

You can also inquire to the companies as to the specs of their front sights. I know the guys at GG&G will give you a quick response.

Actually, the ht. of everthing governs what what the sights will do. I have seen some older receivers that were not to gov't spec, in that the dovtails rails on the flat top were not to the proper ht. from the center line of the bore, too low or high messes up elevation when timed with the front sight mounted on the barrel.
Good shootin, Jack