Several places I hunt don't allow rifles. I've been using my muzzleloader but am thinking about getting a 12 guage slug gun.
As far as the options for the scope, I am looking at three models, all 30mm tube:
I like the smaller size and speed of the 24mm objective lens. But would 4 power be enough for a slug gun, with max range under 200 yards? The 1-8x24 would seem a better option to have the increased magnification if I want it. But the price is more than I am willing to spend. The 1-6x42 seems like happy medium, but I fear losing the speed of the smaller objective lens.
Based on the limited options you've presented, I'd go with the 1-4x24 (assuming the 1-8x24 is not one of your options).
The 24mm objective is more than large enough to let in all the light your eyes can utilize at 4x, while 42mm is a waste of space and unnecessary on a 6x optic.
Keep in mind you're not competing for scores on a target at 200 yards, and I'd bet your average deer is going to be shot under 100 yards? 4x gives you a nice 25-yd aiming point on a 100-yd deer, or a nice 50-yd aiming point on a 200-yd deer.
Finally, there is more handicap in a hunter having too much magnification on a close shot vs. less than ideal magnification on a long shot.
You might also consider a totally different make of scope, perhaps something in the 2-7x or thereabouts configuration (most of which have 32 to 35mm objectives). And if you're experienced in shooting scoped guns, imo, you'll have little desire or need to go with less than 2x magnification.