Taper crimp dia is critical in my 45's. .468 is what I strive for on the taper crimp.
ON the OAL, 1.260 is darn long! As other posters have said, take the barrel off the gun and establish the Max OAL's while you are trying different bullets.
I had to try 3 different taper crimp dies to get the tightest die to get my loads down to .468 or a tad smaller.
My FN likes the 200g Semi wad cutter with 6.0g of Unique, and it is a 50 yard load. 9.6g of AA#5 with a 185g Nosler is another unreal accurate round in the FN. The spring is a strong one in the FN, and this strong spring may be your issue. Your load is on the light side, long OAL drops pressure a tad, lack of good taper crimp dropped pressure a tad, it all adds up.
I have never had a failure to feed or eject in my FN, it is the best out of the box factory pistol that I have ever purchased considering the amazing accuracy. I fell in love with the DA/SA with the decocker...15 rounds of 45 ACP is enough to give you a warm fuzzy feeling!
