I am lucky in having the opportunity to fire a variety of things, including many types of full auto firearms. Regarding the most powerful though it would be: Rifles My own Lawton manufactured .375 CheyTac A rental Barrett M82A1 .50 BMG Handguns A rental Desert Eagle .50 AE Magnum Research BFR revolver chambered in .30-30 Winchester (fellow shooter let me try it) I also got to fire an M69 Grenade launcher. That was a hoot!
I thought about it but then didn't go to a place in Orlando that you could pay to shoot a tommy gun and other machine guns. We were there to bring the grand kids to Disney world. I shoot only what I need to to keep my chickens etc safe.
Most powerful firearm: A Navy deck-mounted 50 caliber machine gun (Small Arms Training onboard ship at sea). Our own: My wife's Smith & Wesson 9mm handgun and a (now sold) Winchester 30-30 Lever-Action Rifle.
I've never been into the big caliber stuff. I don't even hunt birds so I've had no need to take down an elephant. Probably, the largest was an old double-barreled shotgun that my dad had. I don't know what gauge it was but it knocked me on my butt when I shot it once, and I wasn't sure my shoulder would ever recover from it. I was pretty small then, though.
Where the big bore stuff really shines is long range shooting. This is one of my favorite videos showing precision shooting, through different air densities at a distance of 2,751 yards, or well over a mile. Listen to all the factors he’s feeding into his ballistic calculator to make the shots.
.338 is not the best rifle to use for long range shooting, as the drop is significant. My son has a .338 Rem Mag and he has 11 inches of drop at 100 yards. You can tell by the significant elevation that guy had to use to get the distance. I believe the 7 mm Rem mag is perhaps the best for long distance shooting, but the projectile is less than a .30 caliber. There are some Australian guys that shoot a 7mm over 5000 yards but at a lower elevation that the guy in the video. I understand it has to do with the bullet profile through the barrel as well as the profile through the air. The pros in the military often use .50 caliber rifles. Some of those on here may have experience with that but I do not. I have seen it written that, while the politicians wail about so-called "assault weapons", what they really fear is a good marksman at 1000 yards.
All kinds of things can be used, I know folks shooting 1,000 yards with a .308 Win. That’s like throwing rocks IMO, LOL.. My .375 Cheytac is a good one but almost nothing beats the Barrett .416 in terms of flat trajectory. The .338 Edge they were shooting in the video is a plus P round. Regular old .338 Lapua was a favorite for a lot of the guys doing LR marksmanship in the military.
Like others here, I don't find the big bore stuff to be pleasurable. That being said, I've shot my Marlin .30-.30 a few times, and have shot a friend's S&W 10mm revolver. But titanium pocket revolvers with a .357 or a .38+P load will also kick plenty...that 10mm revolver had a long barrel so had plenty of mass to it. I once stood next to a guy shooting a .454 Casull at the range...that was as close to shooting one as I need to get.
This morning I was thinking that I should build and set up a tripod somewhere in case of and emergency coyote sighting. I don't do powerful.
We have a lone one, young, one that has shown itself around the barn. Once my daughter saw him chasing, catching, chasing, catching one of my hens. Daughter ran out yelling and he ran off. Hen was missing all her rear feathers and walked funny for a few days. The youngsters are not skilled. Footprints show he is a bit on the slow side.
The short barrel aircraft 50 cal. It was very late coming into theater in mid 69 finally snagged one when our long barrel jammed so bad it was not repairable so we took it to depot in Vung Tau and we were given a new short barrel in the box. It was a very nice weapon, had a 100 round bracket where you were limited to 100 rounds. If you missed the target by the time you finished a 100 rounds you should find different work. My most remembered time was ripping up a large sampan at close distance, wood and splinters flying everywhere. It all took place in a few seconds while flying under the flares and looking straight into bunkers all up and down a waterway. Much too close but you had to find them and pile on.