These rifles and cartridges are just right for zeroing in on a wolf.
A lot of it depends on what range you plan on hunting at. If you'll be hunting wolves in dense woods, a brush gun or a solid lever action rifle is a great choice. Even a slug gun is a good choice. If you'll be hunting at range, many of the same rifle and cartridge set-ups for coyotes will work for wolves, but some won't. Shot placement is as important as caliber and rifle choice.
Gray wolves are about two to three times the size of the average coyote, making them closer in size to whitetail deer. A good rule of thumb is if you wouldn't feel comfortable using it as a deer rifle, it isn't right for wolves.
The calibers that just don't have enough power are rimfire cartridges and any similar load like the .22 Hornet. Varmint loads in .223 Remington won't cut it either.
Short Range Shooters
If hunting within 200 yards, high velocity, small caliber centerfire rounds like the .223 Rem loaded with hunting bullets (not light varmint bullets) work well on wolves. This means a wide number of ARs are on the table as wolf rifles as long as they are effective at the ranges most people feel comfortable taking shots on wolves.
The venerable .30-30 Winchester is also an excellent caliber for wolves, and there are a wide assortment of lever action rifles in this classic caliber available from Henry Repeating Arms, Marlin (assuming the brand gets back up and running again soon), and several other gun manufacturers.
Henry Model X Lever Gun in .30-30
Ruger AR-556 in .223 or .300BLK
Medium Range Wolf Guns
If you plan on taking shots in the 200- to 400-yard range, cartridge and rifle pairings that work great for pronghorn antelope in Wyoming and Montana can often work great on wolves. While these rounds are a bit more powerful than typical whitetail deer hunting cartridges, the long, narrow bullets do little damage to pelts with proper shot placement at what can be considered medium ranges.
Options include the 6.5 Creedmoor and other short action 6mm rounds, the 7mm-08 Remington, the .308 Winchester, and the .270 Winchester. These rounds typically deliver the best performance in bolt action rifles, but there are a wide variety of rifles chambered in the popular and flat shooting 6.5 CM these days, including precision ARs like the Savage MSR 10 Hunter, which is also available in .308.
Henry even makes a quality box magazine-fed lever gun in 6.5 CM, the Long Ranger, which is also available in a number of ideal wolf-killing calibers. These options offer quick follow-up shots, though the Long Ranger is limited to a four round magazine.
Savage MSR 10 Hunter in 6.5 CM or .308
Henry Long Ranger in 6.5 CM
Long Range Wolf Guns
Some places in North America where wolf hunters tread require taking shots beyond the 400-yard mark, like Alaska. For taking these long shots, you need more fps at the muzzle.
The disadvantage of these long range big game rounds is, of course, they will do significant damage to the hide if you have to take a shot at close range, and they tend to have significant felt recoil that takes some getting used to. We're talking about beefy rounds like the old standby .30-06, the 7mm Magnum, and powerful 30-caliber rounds like the .300 Win Mag and even the .338 Win Mag.
Rifle actions have to be strong to handle these high pressures. Even though there are some semi-auto hunting rifles out there chambered for these powerful rounds, your best bet is a quality bolt gun and a solid optic for these long distance shots.
Thompson Center Venture II in .300 Win Mag and .30-06
Mossberg Patriot in .338 Win Mag or 300 Win Mag
Whatever you decide to use, it should only be high quality hunting ammunition. Even though ammo prices are high, don't trust reloads from your buddy when it comes to any kind of hunt, especially a wolf hunt.