What would be a good powder to start with in a Rem 700 with a factory 22" 243 barrel reamed to AI? I'm looking for a good balance of velocity and accuracy, and of course hopefuly both!

Pretty sure the new Sierra manual has loads for that cartridge. Just don't have it with me.

Just use 243 Win loads and work up. I would use IMR 4350 on the other hand I would not use that bullet.

I agree with Savage99 on the IMR4350.I have had good sucess with that powder in 243.

H4350 gives 3140-3225fps with tiny SD (variance due to temperature) from my 22.5" standard 243 and 85gr speer BTSP. The speer book shows this as the best 85gr powder.

4350 is no doubt a good powder in this application, but my .243's and my friend's .243 AI like powders even slower than this for 85 and heavier bullets. I have had good luck with H4831, and he likes VV N160. If you like the RL series, Reloder 22 would be good, and IMR 7828 is a likely contender.