190gr. bullets in the .284win.? Don't know if you will be able to push them hard enough to get any benefit out of them. Think your going to be in a magnum class round for those I also feel you will have to run a longer throat in the chamber as well so your not pushing the 190's deep in to the case and sucking up any more case capacity. My opinion as of right now until I see some of them.
Based on the information I seen before with bullet dimensions you need a 1-8.52 twist as a min. is the calculation I came up with to stabilize the 190's. at 2800fps. So if your going to try them I would go 1-8 twist.
Myself and Jeff here both shoot .284's on F-Class guns. Both of us run a 32" length barrel and both 1-9 twist. I don't see a 1-8.5 or 1-8 will give you anything more but it won't hurt ya either.
Barrel life is much better with the .284win. vs. a mag. about double the life maybe a tad more. That's why we went with the .284win.
We're pushing 180gr. bullets 2900fps. I can clean the target at any distance with it as well. Both of the guns are shooting 1/3 or better. The only match I shot my gun in last year was a mid range match. Won the match and the 500 yard target I shot a 200-12x.
Later, Frank
Bartlein Barrels