Almost any shotgun with a rifled barrel will produce good groups at 125yds. provided its shooting the ammo it likes best. I have had success with many shotguns with rifled barrels and rifled choke tubes also. I have had no problem with tight groups at 125-150 yds. I have shot Remington pumps and semi auto's, an ithaca 37, mossberg 500's, a browning bps with ( gunsmith installed ) rifled choke. And all shoot respectively similar groups at similar ranges. I would not hesitate for 1 second to squeeze the trigger on a deer standing broadside at 125 yds. if I had anyone of these set-ups. My all time favorite slug gun is my Marlin 512, its very heavy to carry all day long, but its perfect for sitting in a stand or blind all day. Most of my rifled barrels and rifled chokes prefer the Winchester partition golds and lightfeilds, but my best groups come from the partion golds.
This brings up a question for all of you. How do you guys like spending 3-4 dollars per round for good quality sabots? I know I dont. I remember when partition golds where a bit under $8 per box. And I didn't enjoy paying that much for them then. I just don't see me paying 20 dollars a box for the sabots I want. I like to shoot my guns so I can remain accurate with them and with prices ranging 14-20 dollars for a box of 5, the only way I could practice the way I like to, is if I went broke or if I was rich. And since I am not rich nor do I want to go broke, I opt for the plain old rifled slugs out of a smooth bore and hope for shots inside 70 yards. I know it sucks because I have consistantly made good groupings out past 125 yards with good sabots, but with prices through the roof I have to shoot within my limits. Even if that means I can only shoot up to 70 yards. I have also been considering getting into muzzleloader alot more. If I cast my own, its a heck of alot cheaper and I will hit tennis ball sized groups at 90 - 100 yards all day long, everyday I go to the range. I wish you the best of luck in any shotgun you choose, with plenty of practice and the right sabots, you will be shooting excellent groups at 125 yards or more.