Round Bottom vs. Square Bottom Rifling

[Col. Batguano]

I have guns with both types of rifling. With the square bottom, it seemed very easy to find an accurate load. With the round, I'm still struggling to find it. In general, is it THAT much harder to find the right load with RB vs SB rifling? (To be fair though, my SB rifled gun is a cap gun, and the RB's are all flint.)

 

[Carbon 6]

I aplogize for the stray thought, but.
Is there, or has there ever been triangular bottom or pointed rifling ?

 

[Col. Batguano]

Yeah there are a bunch of older shapes that were common back in the day, and could probably still be gotten on a custom basis, but SB and RB seem to be the ones you have to choose from now from the bigger barrel makers like; Rice, Green Mountain, and Colerain.

 

[Spikebuck]

CB...I have had the same experience. I've found that the deep round bottom rifles I have tend to like a ball .005 less than bore with a thicker patch of .018 or .020 for a very tight fit. My more shallow square bottom rifled barrels tend to like a ball .010 less than bore and a patch of .015 to .018 as the barrel ages.

I'll be very interested to follow this thread and see what the experience of others is. I know that I have put a lot more shots down the barrels of my RB groove rifles before finding the magic load than I ever did with the shallower square bottom grooves. I never really noticed this supposed easier cleaning on the round bottom either....seems the same to me.

 

[nkbj]

There's all manner of "round" grooves. Not all are a single radius curvature. The cross sections on some grooves are rather elliptical or a trapezoid with rounded sides and corners. Kinda depends upon the radius of the caliber, the number of grooves, the ratio of groove width versus the lands for what the rifling needs to look like.

Maybe somebody recommembers where it was...
Somewhere on the interseine there used to be pictures of a rifled bore that was down right ornate, like the rifling cutter must have looked like the silhouette of a crown.