I am on my 3-4 reload of factory Winchester and Remington brass in my 7mm Mag. I have been neck-sizing. They feed fine in my mauser-style bolt gun.
I cleaned 38 of them last night and none of them had stretched and they look pretty good. Make sure you coat them, I tend to not get the lube all over them and they get stuck. Whereas the .270 Win rarely do I have stuck case.
I like magnum powders (RE 19, RE 22) and magnum primers in these cartridges. The 350 rem. mag is shorter, but my Nosler book says it like H4831 which is a magnum powder similar to RE 19 and RE 22.
They are much easier to handle than my little .223 cases.