The M357 can shot 81 grain JSB diabolo pellets at over 1000fps for a magazine (5-shots) roughly between 190-216 fpe at the muzzle. I haven’t shot these pellets beyond 50 yards. If you can shot them accurately with consistency, they are more than capable of killing a coyote. I suggest testing them at your intended shooting distances. I have no idea how they perform at 100 yards or beyond.
If you go with NSA slugs, the lightest I’d use in this gun is the 110 grain hollow point. They can be shot well over 900 fps (I got to 982 fps on the first shot) from this rifle. From my testing I would stay between 110 grain and 155 grain slugs. For your intended use (400’), I suggest trying 140-145 grain boattails slugs. I like Griffin airgun slugs for my M357. They make some really nice .357 hollow point boattail slugs. Compres to NSA slugs, Griffins have a thinner wall. I’m hoping that they get better expansion. If I can recover one, I’ll take a photo so we can see how it expands. In my testing, slugs above 155 grains begin to get too long for the magazine to cycle meaning that they will load into the first opening, but you won’t be able to advance the magazine to load another slug. It appears that the limit for slug length is around 0.75”. Beyond that then they must be single-loaded by hand.
As for a compressor, do your due diligence. It’s your money to spend, but when asking that question it’s best to state your budget. I’d suggest a Bauer Junior II, Alkin W31 Mariner, or a Coltri Icon MCH-6; these are tried and true breathing-air quality compressors meant to fill SCBA tanks. There are threads about them and discussing them on AGN. I started out with the .357 Benjamin Bulldog. I first bought a SCBA tank and got it filled at a dive shop for about a year. Then I got a portable Benjamin Traveler compressor. I rarely used it. Then I graduated to a top tier breathing air quality HPA compressor to fill my SCBA tank and have zero regrets about my purchase. For big bores, I think keeping a SCBA tank nearby is necessary if you intend to shoot a lot.
With the Bulldog M357 you’ll get 4-5 good shots depending upon the projectile and fill pressure. I’d hate to do that much hand pumping, especially when shooting to test ammo. My last time out with the M357 I shot about 60 rounds. Here’s a thread in which I tested ammo with the M357.
I’d been contemplating picking one of these up for a while. I didn’t know if I wanted a .457 Bulldog or an M357. I decided to go with the M357 because it’s cheaper to shoot considering ammo costs, I have more experience with various iterations of the.357 Benjamin Bulldog and I’m pretty familiar...
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