Those nipples are expensive, but $65.00 is less than the $85.00 I saw listed about 10 years ago.

When I had the .50 Bauska barrel on my rifle back in the 70's, I was shooting 400gr. RN grooved bullets from an old adjustable Lyman mould, now discontinued, unfortunately.
I made up a die out of a piece of the barrel and pushed the cast bullets through it after lubing them by hand. This engraved the rifling on them, about 1/2 deep, or about .004/5
thou. The rifling was .008" deep and 38" twist.

These shot into an inch to 1 1/2" at 100 yards at the Barnet range, in Burnaby, but I had to replace the stainless nipple every 25 or 30 shots or the groups would enlarge.

I was running double apertures and was shooting 3-position and prone competition at that time with my .308 Match rifle, both any sight, and metallics.

I am quite sure your rifle will do as well, once you get it dialed in.

I just remembered that one of the guys here in BC used to use the Pedersoli Volunteer rifle in .45, for the special weapons moose hunt just 4 hours North of here. He used the multi-grooved 480gr. .451" Lyman bullet and 85gr. 2F, I think.
I also recall he used SPG in the grooves.