JS - that 14" twist would limit the length/weight of the bullets you could shoot, but it should work in either cartridge you mention. 35-40 might be a bit of a waste of case volume with light bullets.

remember to anneal

With all the talk about the 35-40 I thought I would try the 2.080 Starline brass in my 35/40 Lewis. I had to neck turn the Winchester brass so I borrowed one from my buddy and measured it and it seemed like it should work so I got 100 from Graf's and tried 10 today. Sized them down and trimmed to 2.090 , tried it in the chamber( when I closed the action it put a crimp in the empty case so I loaded them like normal with 44 grains of Goex2f(same compression) and shot them off my deck. They shrank.005 so I trimmed them to 2.080 and tried them , perfect fit.No more neck turning.

345 grain NASA from Paul Jones.  Pictures are in beginning of this post. I did a much better resize of that  picture. The other bullet is a Sagebrush 340 and I'm going to have Boomer make one of them pretty quick. The NASA shoots good to the turkey line then gets a little squirrelly.
Browning BPCR with a 10 twist in a 26 inch barrel.

OK.......... first attempt to cast with the 326gr bullet design from above. To make it easier to make the first mold we used aluminum blocks and I've not cast with Al before these. It is tricky to keep the mold hot enough. I've got to make a couple of mods to the sprue-plate so I can get the mold open more quickly so can get the bullet out and refilled with molten lead to help keep it hot. 

The two bullets to the top left are the 340gr Sagebrush and a 317 PJ? that SgtDog0311 sent along. Have the Sagebrush mold, so will try it next. Like the Al mold, it needs some sprue-plate mods to make it more 'user friendly'.

BTW - we used Steve Baldwin's reamer to cut my chamber. Should have the rifle back by end of next week. Steve said that he uses the 2.08" Starline 38-55 sized down to 35-40 and it works perfectly, so that's where I'll start. Definitely do not want to neck-turn brass if it can be avoided.

With the sagebrush mould I have to cast hot 810* F with 20/1 and rotate or fill the mould  quick to get even wts and a nice slick nose. Also changed out the thick sprue plate to a thinner one. 
Big heavy mould for a very long skinny bullet. Takes 10-12 bullets to get mould up to temp.

I call it 810* thats what my tru-tel thermometer reads and my infrared reading a dark piece of steel floating on top is within five degrees.
I normally slow turn my ladle and mould after mating but some are just diff.

Rifle is finished (will post pic's shortly) and did some shooting this past weekend at our BPCR practice day. 
Shooting a 316gr Brooks 'Money-style' bullet pushed by 45gr of 2F Swiss the chickens & pigs went down with no problem. I only had 10 of these rounds loaded, so no chance to try on turkeys.
Shooting the 330gr bullet of my design pushed by 46gr of 2F Swiss there was not problem on the turkeys. It was gradifying that the three (3) rams I hit with this bullet also fell over and all the hits were below center.
Shooting the 340gr Sage bullet being pushed by 47gr of 2F Swiss all the rams hit went down. Again, did not matter where the hit was, down they went.

Shooting a mid-range match this weekend. Will use the small bullet at 200yd to see how it groups. 330gr at 300yd and 340gr at 600yd. Should get a better idea of how it holds up. More later.