A Browning bolt action is really good, but you'll have to find a used one and they are expensive. Same goes for Savage 210, but not quite as expensive.I like my Marlin Model 512, it shoots just fine to 100 yds. They are also no longer made.
There will be many that say Mossberg 500 and Remington 870.
Just looked on Savage's website, they do still make their 210 Slug Warrior.
I trust @Hastings cantilever barrels for all shotguns. I have never seen one that would not perform excellent, with the right ammo on any brand of equipment you choose. My 2 cents
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"There is nothing in the world like a persuasive speech to fuddle the mental apparatus and upset the convictions and debauch the emotions of an audience not practiced in the tricks and delusions of oratory." --American author and humorist Mark Twain (1835-1910)
I've heard great things about the Ithica's. The H&R's are great single shot slug guns...and they're cheap. I have a Rem 1100 that is a decent shooter.
If money is no object...look at a Tar-Hunt. I shot one this fall, and itwas a legit 200yd gun with Lightfield sabots and a quality scope..
I believe the gun I was shooting was 3" high at 100 and like 7" low at 200. Don't quote me on that, but it's close.
Just shoot every type of slug until you find one that groups...That's the key in a slug gun. I've seen smooth bores shoot great groups at 100yds and I've seen rifled barrels shoot 10" groups at 50yds off sand bags with a scope.
Good luck!
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The more you cry, the less you have to pee
I purchased a standard Remington 1100 12-gauge several years ago for deer hunting at Fort Knox. I then purchased a fully rifled barrel with iron sights from Cabelas. I had my father, a machinist, to drill and tap the receiver and mounted a Weaver rail on top with quick release Quad-rings. I also added sling swivels and a neoprene sling.
I have two scopes for the gun. A 1-4x Bantam with circle plex for turkey hunting (with the original 28" barrel and a super-full choke tube), and a Tasco 3-9X40 for deer hunting (with the fully rifled 20" barrel).
At Fort Knox, you are only allowed the one gun and 10 slugs. I went for redundancy on the sights, lest a scope fail me with hard recoiling slugs.
I use Hornady's 300 grain SST slugs at 2000 ft/s available in 2 3/4" loads. I took a nice, tall 7-pt buck there two years ago. Although it was a close shot, the gun is sighted in out to 150 yards, and prints about 2 inch 100 yard groups.