Re: 22-250
I don't have any experience with the 50gr V-MAX, but I do shoot the 55's. They have a slightly better BC, so would buck the wind at distance a bit better. And I think they carry a bit more energy downrange as well. I would give 380 a try. I have some but haven't gotten around to trying it yet. I've been told that 38.0gr of 380 behind a 55gr bullet is magic in a 22-250. Again, start low and go slow. I'm also told that H380 is a bit dirty. Again, no personal experience yet, but will give it a try sometime.
As far as seating depth: each rifle is different. One factor that may force your hand with your Remington is the long throat. Remingtons have notoriously long throats, so if you are trying to get close to the lands, you may not even be able to use a bullet shorter than a 55gr. My Reminton 700 VSF 22-250 likes them less than 0.005" from the lands, but I would probably start at around 0.010" off for initial load work-up. The other consideration is that a lot of these bullets are pretty tolerant of jump. You may just load to factory COAL for starters. I believe it is 2.350", but don't have my manual in front of me at the moment. My load is all the way out to 2.520". It still fits in the magazine, so that is good. If you are going to try lighter bullets, then forget about trying to get close to the lands with a Remington. Just seat them at 2.350".
Another suggestion would be to get a Redding comp seater die. I struggled for a long time, trying to make fine adjustments to the seater die to get the bullets seated to exactly where I wanted them. Then I got the comp seater die. Money well spent. Not only does it load the bullets straighter, with less run-out, but it's a snap to change the seating depth--just dial it down a few more thousands of an inch and you're there.
Good luck in your quest, and keep us posted on how things work out.