bernie
I have two of these guns a 24" model and a 26" and they both shoot really well. I have shot both of them to 150 yards and I am really happy with the results. The 26" I have shot to 200 and I do stay with-in my self imposed 4" group being acceptable.
I am not measuring my loads I am throwing them by volume on site, I am not shooting a fancy bullet all - I was at the time shooting Nosler .458 - 300 grain Partitions and 300 grain Hornady XTP's and/or .458 300 grain Hornady Hollow Points. + one somewhat negative fact I am old - so I am sure the gun is capable of doing better than I can do.
I am currently testing Speer Gold Dots both the .452 - 250 grain and the .452 300 grain. The 300 grain is a remodeled .451-300 grain bullet. The hollow point has been redesigned to provide a higher BC. Speer is claiming .233, with this new bullet - the old .451 was listed as .199 as are the Hornady's .200. I have shot the both bullets to 150 yards and can easily stay in the 2" area, although there is a little more drop with the 250 than the 300's, but the 300's are really looking good.
I am shooting 100 grains of t7-2f loose, Remington 209-4 (410 shotgun) primers, Cabelas 209 conversion, either Nosler or MMP HPH-24 sabots, with the above mentioned bullets.
I believe accuracy of the gun or any gun at 200 yards really can be affected by the condition of the barrel. Your cleaning and treating of the barrel can make inches of differences.
Good luck in your search for that 200 yards.