I don't think I'll ever enjoy a weapon more than the M2 but I also really enjoy lever actions. I have guns that are meant to serve specific purposes but I also have a Henry Mares Leg in .357 magnum that is purely a gun for fun at the range. I can't think of any situation where one of my other guns wouldn't be more suited for the task but damn, it's fun to shoot. What's your most fun gun?

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I think it's a very useful rifle especially for hunting, but I thoroughly enjoy shooting the marlin model .45-70 Govt, like you mentioned the lever action is just fun to shoot.
Definitely not knocking the lever action rifles l, mine is technically a pistol which is the silliest thing ever but I love it 😂
I have a Marlin 30-30, it’s a lever action and definitely fun to shoot. I expected it to pack a bigger punch but the recoil is not bad at all. All my handguns are regular carries that I swap out but my favorite to shoot is my Glock 30, which is a .45 and a fat pig.
Mine would also be my Marlin 30-30. I have tried to build it into a Col. Cooper 'scout rifle' with a scout scope and some other custom work. I don't really ever take it out hunting, but with light recoil and good maneuverability, it's a ton of fun to shoot. I've also never had a forward mounted scope before, which I've enjoyed a lot.
I also have a brace for my G19 with a red dot on it. Not super practical, but a whole hell of a lot of fun to shoot,
I have a .22 cal pellet rifle that is actually really fun to shoot. 200 pellets are only 6 dollars and knocking down squirrels and chipmunks between sips of morning coffee never gets old.
Smith and Wesson 586. Just something about the big old blue steel revolver. .38 is still relatively available in my parts so I haven't had to break into my end of the world hoard yet.
Mine would definitely be my 1873 Bird's Head in .45 Colt, or my Walker .44. Both are Italian copies, not originals. They're a blast to shoot. I occasionally carry the 1873, but never without a modern primary concealed away in case I need it.