Makes me laugh a little. My BFR .475 drove me nuts and it has a much better scope base. No Loc-Tite even with the primer would keep the base screws tight.
I just plain gave up and Accra Glassed the base to the gun and also the screws. I use the Ultra Dot on mine. I don't know how tough your red dot is but the .475 can destroy a lot of those things. The Ultra Dot will not break.
Dump the 2400 and go to 296 with a Fed 155 primer. That gun will shoot if you keep the sights from moving. The .475 is a joy to make accurate. I shoot all kinds and weight boolits from mine and all will do 1" or under at 50 yards and I kept 4 out of 5 on a 6" swinger at 400 yards, shooting Creedmore position.
I don't know your twist rate but if it is 1 in 18", 350 gr boolits work best, up to 400. If you go over 400, you need more velocity.
My (I made my own molds) 420 gr uses 26 gr of 296 with a 1 in 15" twist so you might need 26.5 gr with the 425 gr. 2400 will not bring the velocity high enough for accuracy.
By the way, the 400 gr Lee boolit with 15 gr of HS-6 is very accurate with less recoil.
DO NOT USE RIFLE PRIMERS! Only LP magnum primers. Next you need hard lead and water dropped WW metal is OK, let them age a week before loading. You also need good dies and Hornady is the best for proper case tension.
Here are average, 5 shot groups at 50 yards with different boolits. The large one in the center is 200 yards and I shot the can twice at 100 yards.
Your gun WILL shoot so don't give up. I will help all I can, just ask.