swampfox, welcome to GT!
I haven't had the opportunity to load out the 200 gr. XTP in .400 yet, but have a lot of fun with their 180 gr. XTP and HAP projectiles.
10.7 gr of Blue Dot will get between 1150-1250 fps from my G20SF. It's outfitted with everything stock, except for the barrel (KKM stock-length) and the night sights I put on them (XS Big Dot.)
KKM has excellent chamber support, and my brass is not bulged out after being shot with that barrel. I also use a Redding G-Rx carbide sizing die for 10mm, .40S&W, and .357SIG to straighten out anything which has bulged out.
Ammo by Dillon and Hornady