Yes - primers will show pressure in comparrison to normal shot loads. They'll also get sticky as well in the chambers.

I've wanted to try Longshot myself as I think it will have good results in ball and slug loads.

The slower the powders, the better they seem to work. I adjust wad columns to suit for the crimp I'm using, which is usually a fold crimp with round ball loads.

I noticed one Lyman load shows 40.0gr. with 4756 when using a .690 ball - that's about 495gr. to 500gr.

Still, I'd start with 26gr. when using the 1 1/8oz ball. You'll probably end up with around 28 to 34gr. for max. depending on the ball, wad column and velocity required. A chronograph is useful when developing data.

4756 should take you up[ to abotu 1,400 fps wihtout problem. You might get regulation around 1,200fps, though. Whatever works the best.