choice
What I'm recommending (it's always fun spending other peoples money
) is to skip the lower end of the variable scopes, and spend a bit more on a fixed power 10X or 12X scope with target/varmint features (turrets and parallax adjustment).
Regards "hold". Your shot to shot inconsistency is likely not due to your scope, though it could be. To establish some sort of benchmark for your rifle, get some top shelf ammo and shoot some groups. By top shelf, I mean honest to gosh, .308 match stuff, 168 BTHP match. Most folks rave over Federal, and I have had good luck with Winchester in several rifles as well. It will not be cheap, but one box will be worth establishing what your rifle is capable of with the best factory ammo. When you start loading, getting your homegrown ammo to exceed the factory stuff (not easy with real factory match) will be your goal. Sporting ammo, like the 180 RN's you describe, typically will not equal the consistency of real match ammo. I'm thinking your V/T should yield sub MOA (1" at 100) 3-5 shot groups at 100 with match ammo. If it's not, I'd suspect me ( in this case, you) as the culprit.
Off a bipod, were you supporting the heel/butt of the stock with sandbags as well or simply shooting from your shoulder? If you were not fully supporting the rifle (bags and bipod) your bipod groups are a measure of your accuracy on how well you support the rifle only, not the same as measuring the full capability of the rifle accuracy wise.
Speaking for myself and my rifles, I do not get the same accuracy from a bipod ( especially a portable spring loaded type as commonly seen) as I do from a serious front rest (bench style) and sand bags, front AND rear. I've got a very serious competition bipod that comes close, but I shoot best off bags.