I am going to make my RRA Car-4 a SBR, My uses for it will be a patrol rifle, 2 and 3 gun shoots, and possibly tactical use.   I can't decide on what size barrel/upper to buy.  My questions:   What is the effective range for a 7 inch barrel SBR with a 1:9 twist? What is the effective range with a 10 inch SBR with a 1:9 twist?  If a silencer was added to the 7 inch SBR would that act as an barrel as well and make the effective range longer than just a 7 inch upper?   What would best suit me for tactical and patrol duties?      Thank you for the advice...

Use the 10.5". You don't want to use a 7" with a can. Great possibility of baffle strikes. You'll get better velocity with the 10.5. It's what I use as my entry rifle. Also most suppressor manufacturers will not warranty a can on anything less than 11.5. Some will one a 10.5.

If by effective range you mean how far will the fragmenting mechanism of M193 or M855 work in a 7" barrel the answer is zero yards.  Also silencers dont give much, if any, velocity.

Id prefer a 12" or 12.5" barrel.  I use a 12"... opens up the suppressor possibilities to includea pretty much ANY silencer vs being stuck with muzzle mount cans only and it easily doubles the effective range you can get many ammo types to perform their best.