All of the original Minnie rifles had tapered depth rifling. This was an English or European practice, copied by the Armories in "The States" for their .58 and .69 Minnie Rifles.
The English version had .008" deeper grooves in the breech than at the muzzle - commonly .003" at the muzzle and .011" at the breech- or so I've read.
To the best of my knowledge, the reproduction Zouaves do not have progressive depth rifling (pretty sure mine didn't), but perhaps the newer Pedersoli Springfields may have the progressive depth rifling.
On the other hand, the brass mounted (Confederate version) Italian (Armi-San Polo) Model 1861 that I have does have progressive depth rifling. I have not measured it but a bore scope easily shows this feature in it's 5 groove barrel. I was initially concerned there would be powder gas blow-by causing patch burning, however the denim I use (10ounce) survives the trip down the bore and out again at over 1,300fps in perfect condition. For this reason, I figure there must be 'some' obturation of the ball by the charge. I use ONLY real black powder.
In the initial work-up of loads for this rifle, I was able to get it to shoot 3", 5shot groups at 100meters off the bags using 85gr. 2f GOEX. The only loads I chronographed were with my initial starting load of 75gr. GOEX, which gave 1,308fps average, some 300fps faster than Lyman's old book from the 70's gave for equivalent loads. I felt this accuracy was probably as good as I could accomplish with the short sight radius and military sights on the 24" barrel along with my failing eye sight at that time.
I present this under the premise that tapered depth rifling does not spell doom for a patched ball. The muzzle of my rifle has only .003" deep rifling and a .574" bore diameter. The .575" balls I started with, would sit on top of the muzzle with NO patch. I then purchased a Lee Double Cavity mould casting .562" X .562".
These balls are easily loaded with both my 10ounce denim I measure at .0225" compressed and the thicker mattress ticking that I measured at .0235" compressed. I do not use a hammer nor a mallet. I do use a moose antler tipped short starter. Once started, they go down easily.
Starter second from the right is my Musketoon ball starter.
![](https://americanlongrifles.org/forum/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv638%2FDarylS%2FStarters%2520and%2520Powder%2520Measrues%2FP1142038.jpg&hash=013a280062a7a896e749185114a7507368e56842)