I picked up a box of 180 gr .357" XTPs at Cabelas the othe day but can't find any loading data on them for the 350 Legend. Do you think it would be safe to use the starting loadfor Lil Gun and 175 gr bullets? Should I size them down to .357" first? I know the 350 uses a .355" but Nomercy told me their bores are .357" and I believe him.
if these shoot well they should be a good deer and blackie bullet.

What’s the thickness of your brass? That’s really the culprit in the 350 Legend debacle - Win made chambers too small for the corresponding max bullet diameter to allow “normal” case neck thickness.

So if you figure 2 thou neck tension, your math becomes: .357 + 2 x neck thickness - 0.002 = finished round dia, which has to be a couple thousandths smaller than your actual chamber.

Thanks for the info. What I think I may do because of your post it put a bullet into a fired case and see if it will chamber. If not I'll run the bullets thru my sizing die and bring them down to .355"

NoMercy I took a fired case and inserted a bullet right from the box and it was a no go for chambering. I then ran a bullet through a .356" sizing die and put it in a fired case and it chambered no problem. I believe these 180 gr XTPs will be devastating on deer and blackies.
But right now they are a back up as I got a couple deals on 350 Legend ammo and have 6 boxes of 145 gr Winchesters and 6 more of 180 gr Federals. I can go through those 145s pretty quickly with my AR platform! I wish PA would legalize semi autos for big game.

Did you have any neck tension on the bullet (unsized) with the fired case?

Yes I actually had to seat the bullet with my seating die. And even the sized bullet had a bit of tension.