Your best bet is to get a .223 next... they are good shooters in all configurations (SL, Standard, Heavy) I have four and they are inexpensive to shoot, fun and accurate. The new ones are 1:9 and do well with the heavier bullets... I do shoot Pete's 52 BTHP, but mostly the bulk 55 grain Z-Max (500 pack), and hunt mostly with the 68 gr BTHP's. When you are ready for your third gun, you can fill in the gap with a 7mm-08 or .308... my preferences run to the SA caliber's that is why I am steering you that way, but the LA guys might say your third should be .280 or .30/06. Good luck with your purchase.