Trying to build a budget varmint rifle...

This will go on a Savage 10 FP in .223. I will be target shooting about 50% of the time and hunting groundhogs and coyotes the other 50%. Farthest shots I will probably make will be 300 yds. Majority will likely be in the 150 - 250 range. I am considering three scopes right now...

1) Simmons Whitetail Classic Rifle Scope 6.5-20x 50mm
2) Bushnell Banner Rifle Scope 6-18x 50mm
3) Bushnell Banner Rifle Scope 6-24x 40mm Adjustable

Let me know what your thoughts are...

Also, if I go with a 50mm will I need to get the higher scope rings in order to clear the barrell?