Wait; what caliber is this?

[William]

I know there's a formula for determining what size RB and patch thickness is optimum for one's rifle but I can't remember it right offhand. I received my new micrometer yesterday and was able to measure the lands and grooves of all but one of my rifles.  So here goes, and please feel free to comment, suggest, etc., just no cracks out of the peanut gallery.

Hawken reproduction: Grooves .525  Lands .490

Bown western trade rifle Grooves .510 Lands .495

Big Red (my first Mike Lange made ML) Grooves .550 Lands .540

NSW Chief's Gun .62 (20 gauge)

What size ball for the Hawken and Bown rifles?  What patch thickness?  I've been using mattress ticking which measures .018 mildly compressed and that has worked very well when shooting Big Red.  Obviously, the Hawken has some really deep grooves and I've never had a gun with rifling that deep but curiously it was sold as being a .54.

[DandJofAZ]

54 hawken.  Sounds a lot more like a 50 that would need really thick patching. 0.18 or even more...

Doug

[William]

Okay, an update. The NSW trade gun is now Doug's property but I think that come my birthday in March I may order one just like it only a little longer.  Anyway, I ordered some .480 RB from Midway and with a very thin dry patch the could thumb start it. I think that with the usual mattress ticking I can get it on target one of these days.  I'm going to go ahead and call this a 49 caliber.  Once I've been in the mountains a few years I'll go visit a flatlander gunsmith and have it freshened up, bored out and eventually it will be a .54, just like it was advertised when I bought it. 

[Hanshi]

Well, I have arrived, William, to display my ignorance.  This is my take on things.

The Hawken is a .50
The trade rifle is a .50
Big Red is a .54

With those deep Hawken grooves you'll need to use thick patching.  I'll recommend what I cut patches from; that being cotton canvas duck (.022").

[William]

Hanshi, I'm going to start with the .480 ball and my usual mattress ticking, with Dutch ' s dry lube and then the beeswax olive oil mix. The ticking compresses to .018. That combination may or may not work but regular 50 cal RB at .490 barely goes down the bore. The muzzle is polished smooth and shiny, thus true thumb starting is possible. However,  if I see my patches are burning through or there's poor accuracy then I'll pick up some cotton duct like you suggest.  Does this material compress to .022 or is that a non compressed measurement?

[Hanshi]

William, I measure material by using a caliper.  I squeeze the jaws together with my thumb and forefinger as hard as I can squeeze.  It just seems to me that caliper jaws more closely replicate rifling grooves plus I don't have a micrometer.  I like and use mattress ticking; and as you said, it is usually somewhere between .018" to .020".  Canvas duck is a little thicker but extremely strong and tight weaved.

[William]

Is the cotton duck you buy dyed? 
The tighter weave of the duck intrigues me.