In light of recent conversations, I am, for the time being, going to shoot SB and PC with the same rifle. I plan to shoot standard velocity (Norma Tac22) for SB and switch to a high velocity (Eley Force? SK High Velocity Match?) for PC.
Our monthly matches are organized such that both classes are being shot at the same time, divided by relays. So, my question is this...
Will switching back and forth between different brands of ammo cause accuracy to suffer to any noticeable extent?

Yes it will make a difference. But... Not enough to matter with an iron sight rifle shooting offhand. I would check it out and see if there are any big surprises but I doubt there will be a noticeable difference.

Try shooting 42 gr Eley Contact and you wont have to change ammo between targets.

Thanks, Merlin!
I would take your advice on shooting Eley Contact for both if it weren't for the fact that I have 3000 rounds of Tac22 on hand.

Just ordered up a 1000 rounds of Force.

You will enjoy your choice. No reloading, no brass to pick up, no recoil and way less noise.