Never thought much of the law or game and fish after that

Me to

3 inch allow more payload meaning shot and also allow more pressure meaning potential velocity or moving that greater payload the same speed as the lighter payload.

3 gives you options to shoot either and 2 1/2 does not.

I load 410's in 2 1/2" with tungsten 9's, 60% heavier than lead. This has more pellets than a 12ga 2 3/4 load of 4's and more downrange energy than the lead 4. The smaller size also has better penetration through tissue, feathers or anything. With tungsten, 3" in overkill and a waste of tungsten. If you go bigger on the shot size it really increases the downrange energy. It shoots very tight with just a cylinder or improved cylinder choke.

I designed my own 410 load with TSS 18 shot half ounce out of a 3 inch hall at 1650 ft./s 45 yards on large ducks all day long with number 8 1/ 2 shot they were sent off to ballistic products and tested for data and they’re just at 13529 psi I can share the data if interested i buy the shot for $245 for 5 pounds but this load has to be loaded in a 3 inch hall to reduce pressure spike

"sent off to ballistic products and tested"
You guys do some impressive stuff these days

I did not know 2 1/2" long guns were still produced.
Good ammo for them is not over flowing.
Speaking of the Rem 4 5 and 6 shot hi-vel.

I used some .410 PDX1 defender loads. It kills turkeys stone dead at close range. 30 yards and under.
It contains 3 plated discs and 12 plated BB pellets. It's a 21/2" shell.

Slug loads are now legal in Mo for Deer.

I bet at close range and good shot placement a .410 slug would be deadly.

Sorry been busy dealing with a bunch this bunch of Yahoo's, anyhow , idk just make up some nice hand loads , might try something for coon or grey fox

The Henry lever action shotguns in .410 are chambered for just 2 1/2" shells. I cast and load my own slugs in 2 1/2" hulls, nothing special, but they shoot well.

I wish that wasn't the case for just 2 1/2 .

AAron,
If you are thinking about getting one, make sure you handle one first. They are built on the .45-70 frame and quite heavy. If you are thinking about walking around with it say squirrel hunting or grouse hunting, they get pretty heavy. IMO, they could have made it 2 lbs lighter and still been plenty strong enough for the pressures a .410 generate.