I'm not aware of a 30 Miller, you may be thinking of a 32 Miller which is .321 groove Dia barrel.  The 32/40   38/55  and the 32 Miller are the favorite Schuetzen cartridges. JGS and other reamer companys have these reamers in stock. Barrel blanks are available from Douglas-Shilen-Krieger-Smith and etc. they all make good barrels. leadball

I built a No. 3 into a .30 cal. 32-20, 1-12" twist barrel.  Does quite well with 189 gr. bullets...when I do my part.  The 32-20 has just a little less capacity than the .32 Miller, from cases I've been given, but with the smaller bore, it's insignificant.   

David
Montezuma, IA

38_cal,  This is where I get confused. You built a 32/20 using a .308 barrel? Is this what you did? Normally a 32/20 has a bore diameter of .312 or something. I would like to use a .308 barrel with a cartridge that can handle a  max 200 grain bullet out to 200 yards. i just wondering if this idea will work.
Dan

Dan
Brass can be made from .357 Magnum, .357 Maximum or 5.56x50R Mag cases. I use .357 Max brass and have only used 2 cases in two years, one for the breech seater tool and one to shoot! CH4D makes a sizer die. It needs to be shortened slightly to remove the generous lead in chamfer to the die. I place a case on TOP of a shell holder that is solid and flat (it came from a Lyman ram priming tool that looks like a size die) and simply size all the way to the top of the rim. Cases can be driven out of the die with a dowel rod easy enough. Shorten to the proper length and your done making cases. 

The #3 contour barrel is the largest you can fit to a Ruger that still has the hanger. Some folks take the hanger off and make provisions for the mainspring attached directly to the barrel. Like I said, mine retains the hanger. 

Twist is 1-14 I think. Bore is .321. Length is 30". I've thought about nocking the length back to 28" to improve the balance. Steve is trying to get me to add lead to the butt instead. Boy, is that statement going to haunt me from my "friends". 

I am using a two diameter Hudson Ideal mould casting 185gr 1-30 alloy sized .321 and lubed with Emmerts spiked with lanolin. Bullets are breech seated .060 in front of the case and a 3/32 cork wad is .100 in front of the powder. Primers are small rifle match Federal's. Powder is H-108 and 13.5gr. This moves out at 1485fps measured 10 ft from the muzzle. This is safe in my gun and I make no claims how it does in anything else. 

Let me know if you have additional questions.

MI-Shooter,
   Thanks so much for the information. I've gone to the Green Mountain page and see that they also make the #3 contour in .22 LR. This would be ideal for my project as eventually I'd like to relplace the rimfire barrel that came with my rifle. This .32 Miller cartridge seems to be just what I've been looking for, I've always thought that the extra space in the 32/40 was detremental to accuracy. Some good scores have been shot with that round though.

But Dale u can shoot the Ballard Match and not shoot black powder!!

Dale,
   Thank you for your advise. I already have a Ballard chambered in 32/40 so if I want to shoot black powder I can use it. The 32 Miller seems to be a well thought out product. Exactly the correct powder capacity for the velocity you want with a specific bullet. This philosophy is what has been driving a lot of other target cartridges. David Tubbs 6XC comes to mind, and of course the PPC line is hard to beat in the benchrest game. Looks like I just talked myself into a .32 Miller chambering job.