I made it out to the range for about 2 hours today and decided to just work with the White Ultramag .504 and the pack of FPB's that I picked up at Walmart. I first loaded 100 grains of 777 3F and the FPB and then tried to shake it off the powder, it stayed put even in the clean barrel. It loaded about like a power belt or no excuse bullet. As the picture shows the first shot went high, the next 4 grouped pretty good for no swabbing, this was at 50 yards with the Lyman 57/17 peep sights I have on the rifle. I was using a CCI musket cap for ignition.
I then swabbed the bore and increased to110 grains of 777 3F and shot this group with a sight adjustment for the last few, no swabbing between shots.
The 110 load seemed to shoot a bit more consistent on velocity so I stuck with that and moved to the 100 yard bench to fine tune the sight in. I didn't chrono the 100 yard shots due to the need to move the chrono. This target is a 50% life size elk target with the center spot being about 2.5".
The sights were adjusted after the first shot and then shots 2,3 and 4 were shot for a group of right at 2". I pulled shot 2 just a bit I think since the other 2 were almost touching. Here is the target from further back.
That finished up the 15 bullets I had and I needed to get back home to finish packing for my next trip out of town tomorrow. Over all I was happy with the results from the FPB, I wasn't sure how it would work in the Whites ,504 bore. The bottom edge of the FPB measured .505 at the bottom edge of the bullet while the rest of the bearing surface measured .499 or so.
This was the first outing with the new sights, I do have the same setup on my GPH, and I was happy with how they worked. Here is a not so good picture of the sights from the shooters perspective.
I think I may have a good elk load in the making.