I had an opportunity to pick up a couple Uberti High Walls without braking the bank.  After slugging the bores, I was surprised to see they were larger than expected.  One, a 38-55 measured 0.384 and another 40-65 measured 0.410.  Has anyone else found this with Uberti's?   
The 40-65 may not be a problem, but the 38-55 is another issue.  Not sure if I should have a custom mold made or maybe have it lined to a smaller bore.
Any thoughts are appreciated.
Mike.

JOhn Boy, you probably have the Pedersoli barreled 12 twist
"Uberti" , which is specified per collaboration with Dan T
at a 378 groove dia .
4570Mike,
If that big you have a "regular" Uberti, whic are notorious for 
oversize groove dia. A friend has a 405 W Uberti, way over
groove at about 0.415
beltfed/arnie

Well, lets try this. My Uberti, which is 15 or so years old, was built to the original specs apparently. The Ideal Hand Book of Reloading Ammunition, Number 34 (1940), lists in its table "Groove Diameters & Twist of Rifling of American Rifles" this for the 38-55: groove diameter min .379, max .3795 and twist 18. My (measured) rifle's groove is .379 and the twist is ta-da! 18. I recommend NEI 379245 mold. I suppose that I should add that my Browning BPCR 40-65's groove is .410. And the Ideal table for the 405 Win shows .413 to .4135 so .415 is not terribly over.

My Uberti High wall has a bore of .382 and I have a number of custom molds from Accurate molds, double cavity for under $100, will drop bullets the size you specify with the alloy you specify. If you are getting a good price on the rifle, a few extra dollars for a custom mold is not a big deal, in my opinion. How much were you planning on spending for a mold, and what is the extra price for a custom mold?  The 38-250J, 38-300J and 38- 315J   Accurate molds are basically the Saeco style but without the taper. Joe S

So far, the 300 gr is doing pretty good, got some tipping with the 315 gr bullets, and some good results with the 250 also. I ended up using the 250 with 4227 for offhand and the 315gr bullets for benchrest with M&P 300 powder. However, a few weeks ago I re-ran some tests with IMR 4759 and got some promising results. Unfortunately, the shooting season is almost over  so I probably will not be able to finish my testing till next spring but it looks like I will be using the 300 gr bullet for benchrest next year, with either M&P 300 or IMR 4759. 4759 is discontinued but I have a healthy supply. IMR 4227 is a popular powder also. 
Joe S

Joe_S wrote on Nov 10^th, 2016 at 10:15pm:

Again, thanks for your input JoeS.  I have ordered an Accurate mold. Another question; I needed to specify a diameter for the nose portion.  I measured the bore to be 0.375 from a slug and specified this for the nose; do you think I should reduse it by a thou?
Mike.

I had a similar problem with a Pedersoli Hi Wall i bought a couple of years ago , i had  also bought a Lyman 378-674 mould to use with the rifle but it didn't shoot too well  so i slugged the bore and it measured .3805 .After asking for advice on the forum i had  Tom at Accurate moulds  make mould #382310E in his catalogue also i had Leo Bumphrey make me a similar mould both are tapered designs for breech seating both shoot very well and i would recommend either. G40

Well that answers a question that has plagued me for years.  Why does my Cimarron .45/70 have a .460 bore diameter.  It shoots .460 cast bullets great.  It key holes .457 and .458 jacketed or cast.  I have no complaints with the rifle after I slugged the bore.