I have the standard stainless synthetic Optima V2, 26 inch barrel. It's a very accurate rifle. I can put three shots together touching at 100 yards if I do my part. It opens up to an inche or so at 150 yards and 3 inches at 200 yards. I use 100 grains by volume of Blackhorn 209 and the 290 grn Barnes TMZ (yellow sabots). I could not get the Barnes TEZ (blue sabot) 290 or 250 grn to shoot consistently out of mine. I can't remember why I never used 250 grn TMZs. I zero at 150 yards, and I believe I hold over 9 inches for 200 yards and it's 3 inches high at 100 yards. I don't have my info in front of me to be sure, but those are pretty close numbers.
I picked the Optimar because of price and I liked the standard stock shape it has better than the goose neck found on the standard Accurra. The Accurra Mountain Rifle is similar to standard Optima V2.
I wouldn't get too hung up on the barrel length. If you can find a ballistics chart for the barrel lengths, it's not much difference between 26, 28, and 30 inch barrels. Like I want to say it's less than 80 fps across all three lengths at 200 yards.
Blackhorn 209 and a tipped bullet (Barnes TMZ/TEZ or Hornady SST or one of the Parkers) are needed, to get to 200 yards with any consistency in the 50 cal muzzleloaders. I never tried the CVA bullets. I have tried Winchester, Federal, and CCI 209 primers and found the CCIs to be the most consistent. The Winchesters burn the cleanest but don't seem to ignite the same each time. I would always get a flyer in three shot group with the Winchesters. The Federals are pretty good, but not as available around me. You need to be consistent with the powder and pressure to seat the bullet/sabot. I only clean the barrel after every three shots. I didn't notice a difference cleaning between each shot. Blackhorn doesn't dirty up the barrel very much. If you aren't familiar with Blackhorn it's hotter than regular black powder/pellets and a magnum or full load in it is 120 grains by volume in the Optima and Accurra. The magnum load is...not fun to shoot and my accuracy falls off quite a bit with it. Though that may have just been the bullets not stabilizing well with the bigger load.
Loctite all of the screws on the scope mount that comes with the Optima. It will rattle the screws loose after few dozen shots. I believe EGW and maybe Warne make picatinny rails for it, but the single base scope mount that comes with it works well.
