How concentric is you ammo? TIR for run-out? You said you thought you had a good load, was it shooting better in cooler temps and if so how much better? It may be a combination of a few different things like:
1. Variation in load due to temperature. IMR 4350 isn't as temp stable as H4350 for example.
2. Check your loads run-out.
3. Who bedded it. Do you have pics?
4. Action screw tension can affect groups size.
5. How far off the lands? Sometimes seating further off the lands or closer to the lands will alleviate the extreme "flyer".
6. Check all scope mounting hardware (bases, rings) for any screw backing out or coming loose. If there's a problem with this, loctite them.
7. Use a scope of known quality: One that tracks well, holds poi, doesn't have a problem with parralax.
