Gm54-120 - I think they are 240gr, and I think you are right about their terminal performance. I just couldn't get them to perform as accurately as the PT Golds. I just got some of the green crush rib sabots, so I will try them out with the Cheap Shots to see if that improves accuracy. If it does, I may re-zero for that load come next whitetail season.
Curious though...why would you recommend the PT Golds for practice over the Cheap Shots? Sure, they are not as expensive as Barnes, but they are a LOT more expensive than Cheap Shots! Also, when you say they are "pretty effective" on game, have you had an experience that would keep you from calling them "very effective?" Both deer I shot with them were toast.
Muley Hunter - From what I understand, the 300gr PT Golds have a pretty good BC and are very accurate in long-range situations...more so than 260gr (BH209 was used in the report I read). If you do not keep the coyote pelts, that is probably your best long-range bet, and of course it would work well on elk and bear as well. I would be interested in hearing reports of a 180gr projectile out of a .50 cal. For some reason, I would think it will be difficult to keep it accurate at longer ranges. And, come to think of it, 300gr or 180gr on a coyote...either way, the pelt is toast.
If you end up using BH209, I do recommend testing out the red crush rib sabot. You may find that you get a bit more velocity there.