Well, a few years back at State Shoot I picked up some old Meteor 1FG (Made in Great Britain) black powder and test fired it in one of my .45 caplock rifles using a 55 grain load with a .017 spit patch and .445 round ball.
I fired 11 shots in a row out of this rifle without swabbing between shots, and to be quite honest I think I could have kept on going a few more shots without swabbing but I packed it in for the day as the shoot was over and I was just testing the powder.
I was surprised at the accuracy I was getting from this powder and my load combination from the 36" GMB. Truly an excellent powder and I picked it up for $6.00 a pound. I wasn't going to pass that price up 3 years ago.
I don't know how Goex 1F works, I never used it. I usually use 2f & 3f Goex only.
Still,,, if this Meteor black powder was available - I'd be using it.
I know this post probably is of no help, but that's my experience with 1F BP...