I did some tinkering
I have no doubt this little Bullet will shoot in a 1:48 Twist. These are Cast of Certified Pure Lead and weigh in at 260 Grains. IRONICALLY This bullet measures Exactly the same Length as my .45 Cal Maxi Hunter at .690, And of Course the TC Maxi Hunter was designed By TC to Shoot in Their Stock 1:48 Twist .45 Cals
They Drop from my Mold at .454
Here they are Reduced to .449
And here they are Reduced down to .442, Note the Red arrow is pointing at the Top of the Bearing surface i have exposed, By reducing down you can see the Bearing surface quite easily. You want to Patch EXACTLY to that Point, and no further up
Sized to .442
A few of them Short Patched
Held Good n Snug in my Calipers They finish Patch to .449 With my Particular Onion Skin paper, My stuff is the Old 25% Cotton Onion Skin. I have found .449 to be IDEAL For .450-.451 Bores, They just hold the Bore on the way Down