I am also hunting elk in Colorado this year, so as others have stated, all the plated powerbelts are legal in Colorado. However, I would not consider 3" groups at 25 yards to be adequate. What if you wound one and need to do a follow up shot at 75-100 yards. Very doable if you find the right load.

As also stated, I have had a 3 year attempt at finding a decent load for my Omega. What I finally had to do was to go back to using pyrodex. I love the clean up of the newer powders like 777, but just can't get really good accuracy. My Omega shot a 5" group with 777 and no excuses at 25 yards! With the load mentioned above, I shot a 3shot group with 2 in the same hole and 1 shot 3/4 inch away at 25 yards.

It also seems like Omegas don't like big conicals. While I do like bigger conicals with elk, I think that the load above will be more than adequate. I also had half way decent accuracy with 348 and 405 grain aerotips and 777. My gun liked 90 grains of 777 with a 348 and 95 grains of 777 with 405's. However, neither load came close to the above grouping. I was getting 8-10 inch groups at 100 yards, and that was off a bench with sand bags.

Remember that loose 777 is about 15% hotter than pyrodex, so my 90-95 grains has plenty of energy for any elk in Colorado (aprox equvilent to 105-110 grains of black powder/pyrodex). Not only does your 120 grains of 777 load pack a real wallop in recoil, but is approaching the safe limit in the Omega. 120 grains would be equvilent to about 138 grains of pyrodex. Probably still safe, but I would not hesitate to drop the load down to 90 grains and see where she hits.

If I were you, I would grab some different sizes of powerbelts and a jug of 777 and pyrodex and see if you can get some better accuracy. We are shortimin!

Good luck!