Yes but don’t expect ME to pull & mark your target! Inbound trajectory’s about 60°.
When they used those for Palma the targets - and scoring rings - were square for a good reason.
Hate to hijack or derail this thread, but I just gotta call BS on this. I've heard this myth many times and it generally gets perpetuated by guys that have never shot the guns or pulled targets for them. Now I'm not exactly a great math guy, but because of the layout of our local 1000 yard range and knowing where the impacts are for the BP 45's as well as 308's and the guns that shoot a bit flatter, I thought it would be fairly easy to figure out the impact angle at the target.
Made the little drawing below. The numbers aren't exact and the drawing is not to scale, but because this range is my second home, it's pretty damn close and playing with the dimensions doesn't change the angle much. So, I come up with a 5-6* angle when bullet meets target, but like I said, I are not too good at math. I texted this to a friend, an engineer type and he said it seemed right and said to cross check based on maximum bullet height vs. line of sight and about where it occurs and use that ratio. So, the MRT is something like 50' @ somewhere around 550 yards down range an damn if that don't cyfer out to 5-6*.
Surprised me. I've been playing the Black Powder Target Rifle game for 20 years and I always thought it was 10-12ish degrees and never had a reason to try to figure it out, but I guess half that makes sense since the holes in the target appear nice and round unless the shooter is trying to push too long of a bullet through too slow of a twist. Kinda like modern rifles! That Greenhill guy was really on to something.
About the targets, we still use a square target here in the Wild West

The original Creedmoor targets that I'm familiar with were a 6' x 12' rectangle with a 36" aiming Black, some made of steel, that the "markers" marked with paint brushes on long poles.
Sorry to bore anyone with all this, but I just wanted to try to correct bad info. Then again, maybe my math is as bad as I think it is.
To get back on this threads track, I love the 308, have 4 of them right now including a very accurate Palma rifle, and like Mr Boyd, it was my first centerfire rifle as well, bought to shoot HP Silhouette with a bunch of Cheeseheads at Columbus and Lodi