Point of impact shift.

TreeMan said:

I had to go back and read the original post again. I didn’t see that he wrote 100 yard offhanded. Heck I’m happy to get all my shots in the black of a target at 100 yards using a bench rest and sandbags. OP it is my firm belief that muzzleloader groups should be determined at 50 yards off of a bench and bags. Offhanded at any distances is a fruitless endeavor to determine groups.

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TreeMan said:

-0° windshield washer fluid.

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Greenjoytj said:

At 36” long barrel + loose PRB + fouling from 3 previous shots + high MV from very large powder charge of fast (3fg) powder = PRP mostly skidding across fouling filled in rifling, the barrel starts acting like a partial smooth bore, therefore the useful grouping ability with this load combination in this barrel barrel is gone.

Your PRB is just barely taking rifling imparted rotation in a clean bore.
The slow twist in clean rifling and the long barrel imparts just enough rotational stabilization to the PRB to lull you into thinking you’ve discovered a great load.

In reality it a one trick pony, or rather a 1 to 2 shot accurate rifle.
It maybe fine for hunting big game but it‘s a dud for all day target practice at the range without a lot of wiping between shots to keep the PRB on target.

I would perform the following test:
Use a larger .535” ball and your regular patch material.
In a clean barrel insert a 6” x 1/2” brass rod, start the larger PRB ½” into the bore.
Now gently remove the PRB slide hammer fashion via the brass rod previously inserted.

The test is to see if your PRB has acquired the proper pattern of light and heavy patch weave marks embossed into the lead ball. You must see lightly embossed weave marks over the grooves and a deeper embossed weave pattern over the lands of the rifling.
It you don’t see this proper all around weave marks then use slightly thicker patch materia.

The ball is gripped by the patch and the patch takes the rifling.
At the moment of firing the ball is slugged up wider by the sudd acceleration and the mass of the ball must obey Newtons First Law of motion so it gets slightly wider getting an even better grip on the patch and rifling.

A larger PRB would be better served by by reducing the MV by using a lesser charge weight and the long barrel would make good use of slower burning 2fg powder so you could use less Powder. Smaller powder charge would not clog the rifling as quickly.

The tight fitting PRB is harder to load but that’s is because it is cleaning the rifling a bit as it is pushed down. Thereby extending the accurate shoot ability of the barrel before wet swapping is needed if ever.

100yds off hand shooting proves the skill of the rifleman but requires a proven accurate rifle and that is determined by bench rest shooting until a tight grouping load is developed.

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45man said:

I also agree with a .535 ball and tight patch to see material engraved at the grooves. A 1 in 72 twist indeed needs velocity but I would be using FFG. My load is a .535 ball, .020 denim patch and 100 gr of FFG. It has held stable groups to 200 meters. First shot to over 200 without wiping. If things tighten up I apply more lube to the next patch.

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