I have a .260 and fireformed my brass yesterday. I was usiong RE-19 and found that not all of the powder was burning leaving a few grains behind in the barrel. I was thinking of switching to I-4064. Anyone want to share their loads? TIA!

AirB, are you necking other brass up/down, is that why you are fireforming? I think RL19 is a bit slow for fireform loads. You are on the right track dropping to a bit faster poweder.

I have shot the 260 quite a lot, what bullet weight are you wanting to shoot? I have a couple of good loads with IMR 4064 and the 85 to 90 gr. and the 120 gr. bullets. With bullets heavier than that I go to a 4350 class of powders. RL-19 isn't a bad choice for the medium to heavy for caliber bullet weights in the 260. It is a 4350 class of powder, just a little bit slower that IMR or H4350, but still in the basic burn rate. There are others here that use IMR 4064 with good results. I have also heard that RL-15 works well with the lighter bullets.
May I be half the man my grandson thinks I am....RiverRat

The .260 Remington has an inborn fondness for VARGET!! (as do a lot of the smaller capacity varmint and deer chamberings!!!!) Try 43.0 grains of Varget behind a Nosler 100 grain Balistic Tip. Yeilds 3204fps from my 24" barrel. I don't guess I'll argue with .391" at 100 yards either!! For another choice, go to H-414, 48.5 grains behind the 85 grain Sierra Varminter (3303fps) or the 100 grain Sierra Varminter(3249fps). using Re-19 behind the 85 grain Sierra yeilded 3140fps and .757" in the same rifle. Stick to the VARGET OR H-414 for ccuracy and velocity!! GHD

Not necking up or down as of yet. I will be soon. I was shooting the Sierra 120Grn with 43.5 grns of Re-19. I will try the I-4064 and the Varget to see which produces the best results. Thx for the help.

Thanks Ed, I understand that. It's just if someone says they are "fireforming" it usually implies the case is a significant diff. from the chamber, ie. an AI.