RE: Rem 700 & Powerbelts
Your powder charge looks about right. As for the size of the powerbelt, your rifle will tell you which one to use. I would suggest getting some 295, 245, and 348 grain powerbelts. I would start with the 295 for the first outing.
A word of advise.. Since your shooting Triple Se7en, be sure and pull the plastic button off the bottom of the powerbelt before loading. You will see a small lead spike on the bottom of the actual bullet. Take some borebutter or gun oil and put some on that spike of lead. Then push that button on and off a few times. Now load the powerbelt with the button replaced, in the barrel on top of the T-7. The reason for this is Triple Se7en produces a much hotter ignition then most powders and it has been know to cause the powerbelt to keep the button. You want that powerbelt to loose the button as soon as possible after it leave the barrel of the rifle for the best accuracy. Most buttons are about 15 yards down range. On some of the unlubed I have found them over 30 yards down range....