Nice looking rig...are you going to "Big Loop Lever" it? I keep thinking about it, but would need two levers to handle the 3 different barrel/cases...a standard 30-30 and a 450 M.
Having a lot of bullets in a couple of weights is ALWAYS a great excuse to build/modify a rifle.
...and you can cut down the length if they don't quite work...making a nice big wadcutter so to speak. I'm guessing Jes would have cut the twist to handle the bullet length...a "standard" 1-12(358 W) to 1-16(35 Rem and 35 Whelen) 35 cal twist will work OK for the most part.
Optimum twist for a 35 cal, 1.5" long bullet at 1700fs is roughly 1-13...your bullets are probably about 1.35" - 1.4" or near that. Post how long your bullets are and I will run them through my twist calculator or you can do it as there are several online twist calculators available. It is the bullet LENGTH and expected velocity that determines the best twist rate.
You could load both those bullets up to 2000fs and still be well within the Marlin safe pressure zone. H4895 seems to be a very good powder for the 356 W case and heavy bullets. I use it, RL-15, Varget, BLC-2 and AA2495 in my rig, with Varget and H4895 getting the nod for accuracy and BLC-2 and AA2495 having the highest velo and lower pressures. I've used both 356 W and 358 W cases interchangeable, mixed in the mag tube and had no problems with cycling or ejecting them. I also tried about half dozen other rimmed, semi-rimmed and rimless cases and they all worked without a hitch.
I don't load to SAAMI specs of 52KCUP for both the 356 and 358 Win, prefering to keep the pressure running 48-50 KCUP which still gives plenty of velocity and better accuracy with the 220 Speer FP.
Personnally tho'...I carry my 12 ga 3.5" Mossy pump with handloaded slugs and 00 buck when I go walking at night...I live in the boonies of Oregon and have black bear and cougar come visit now and then...but my dog goes along which keeps any inquisitive 4 legged critter a long ways away...2 legged ones are my main concern as there are some real crazies living scattered around the area.
I've only been bothered once with a starving young black bear at the gargage bin that wouldn't go away and I had to send him off with a 38 special in his head.
Felt a bit sad about that...his ribs were showing and his skin was sagging and he was bawling like a baby. Couldn't be helped, I live in cattle country with lots of young kids and stock running all over the place and he was a danger to all.
Keep us up to date as you work out your loads...I haven't gone over 250gr and never even thought about it, but if yours works out well I might just dig around and see what happens in my shooter.
Luck
