Hi Guys, I am always in a quandary, on this stuff!!! I'm in the process of trying to order a new bullet mould from Accuate Moulds. I am using 20-1 lead, 32-40 caliber, Winchester HW, bench rest shooting, 200 yds. The bore diameter on the muzzle end of the Stevens barrel is (as best i could slug and measure) at .320/.321. I assume this is the original Steven factory bore diameter, (fyi looks like new) and I do breech seating with a Webber seater. So what should I come up with a realistic bullet band diameters for my new mould? The barrel has a 1-16 twist, doesn't seem to like much over 175/180grs, so I was going for a tapered 165gr bullet and I was thinking; .319/.320/.322/.322. Any thoughts, too small or too big?  regards

For what it's worth: The old Ideal tapered molds that were made for original barrels (16:1 twist) were about a hundred and ninety grains or a little less. Depends on the alloy. I have particularly loved shooting a #319289 for over thirty years. I did pretty well with the Hudson variant too though my rifle isn't 'throated' by anything other than age The measurements are pretty much what Randy suggested and you already suspected. My original barrel high wall is a bit bigger bore than your Stevens, but not much. Go with that.

yes I meant to say the groove diameter is .320/.321.  I have noted that several people and even some long time shooters in my club (DSA Schuetzen) say that they have been able to shoot 1-16 twist, well, with 180-205 bullets. I have two moulds a 183 Ideal/Lyman and a 198gr PJ mould and I can't seem to get them to shoot very good all. Thats why I was thinking of trying a lighter bullet. I ran a twist calculator a couple times (using lead density) and it usually comes up with a 160-170 ideal bullet weight for this twist. Maybe I am going to try my same bullets, resize them and change powders???  thanks for all the replies

I will throw out my opinion for what it is worth.  You should be more worried about the length of the bullet and then the weight.  If you look at the profile of some of the older bullet designs they were not a long nose profile and so could weight more for the length.  In my Douglas 16 twist barrel I shoot a Barnett bullet that is .980" long and 185 grain to good effect at 200 yards.  I would look for a bullet around that length to start with and as you gain experience go from there.  I do not think you could go too wrong starting there.
Charlie