I have given up entirely on trying to use my burris fast fire optic on my fnp45 tac.
It is impossible to keep that type of optic sighted in. I say this because when mounted on the slide, the lock screws in the rear of the sight are completely obscured by the rear iron sights.  The only way to lock the lock screws is to take the optic off, lock the screws and remount it. In doing so the sight is then no longer zeroed. I wasted about 200 rounds trying to carefully lock my burris but without success. I have used this type optic on many other platforms without issue. But it would seem it's not fit for the fn45 tac. Also note the doctors red dot would have the same issue as the burris

my Trijicon RM02 (LED RMR 8MOA) was made for the FNP 45 Tactical and holds zero...no issues...I thought one of the Docter red dots was as well...
Bill

You are correct.

Yes it is made for it. But it is the same as the Burris essentially. I CAN NOT keep the zero when the optic is removed to engauge the lock screws.
If you do not engage the lock screws your zero will wonder.

Should have gone with the RMR.



I've got a fastfire on an AR pistol, and it works for that, but it's just too snug on the FNP45T

I think that will be the way to go (rmr) .
Lucky for me I took my burris off a larue ak iron dot and did not but it just for the fn tac.
So back it goes to the ak.....

Question to the original poster did you use the FN supplied mounting plate to mount the Burris fast fire.

I have a Docter sight on mine and to tell the truth I thought it was going to be a disaster with taking the sight off and unlocking the screws and making the adjustments then relocking and remounting but honestly this thing holds zero great. I had to remove it a few times as I made my adjustments closer and closer to dead on but it did get better and better every time I adjusted.

It was explained to me that the Docter might fit the FN mounting plate more precise than the Burris but who knows.

I have two FNP 45 tacticals.  One with an RMR and one without.  At first I really liked the RMR, but just found it "to busy".  I took it off and am going to put it on something else.

I ran into this problem with my FNP45 Competition model and one of the primary arms reflex sights(burris style) A jewelers screw driver, some heat, pliers, and a dremel tool was all it took and I had a tool that would fit between the sights and the lock screws. I also made a tool out of a 7.62x54 case and the dremel cut off wheel. I know the comp sights aren't as tall at the tac sights but i'd imagine it would work too. I can post pics if need be. By the way, I never thought a reflex sight on a pistol would be so much fun when shooting steel.

I did use the provided "doctors" mount plate. But from everything I have seen the foot print of the Burris and Doctors are the same. The Burris fits nicely on to the guide dowels on the mounting plate.