Min fps for reliable slug expansion in .357

[JungleShooter]

At what range are you placing the gelatin block for expansion tests? Are these pellets/slugs at 800++ FPS at reasonably normal hunting distances?

For clarification:

(1) I have not conducted these tests, only summarized what I found online.

(2) The velocity that is critical to expansion is not the muzzle velocity but the impact velocity.
Depending on the projectiles BC, the ranges at which an impact velocity of 800fps can be maintained varies wildly. E.g., calculation with ChairGun of three .22cal HPs, shot with a 36FPE gun:
● H&N Crow Magnum (18.21gr) published BC 0.022 (GA) (though likely lower for a "flying ashtray" at such high velocities)
➧ MV=944fps | IV=800fps at 24 yards

● H&N Baracuda Hunter Extreme (18.52gr) published BC 0.026 (GA)
➧ MV=936fps | IV=800fps at 27 yards

● FX Hybrid slug (22.00gr) published BC 0.080 (G1)
➧ MV=858fps | IV=800fps at 40 yards


Cheers,
Matthias

 

[Airgun-hobbyist]

Here's some food for thought... When it comes to lead and the intended critter, there's always a balance between projectile weight, energy dump, expansion, critter penetration and the needed speed to accomplish said.

Those hollow Varmint Knockers and FX Hybrids were designed by bird and rodent "pesters" and they do very well with those size of critter. On a meatier more robust game animal that design of a slug, even weighing more, are usually a poor choice for penetration because they dump all of their energy within three to four inches of penetration. A more solid hollow point slug of the same weight will have far better penetration and possibly (ideally) pass through for two leaking holes.

Pictured left to right, 240 grain, 325 grain, 350 grain. Same lead, nose shape, and hollow point. Had the heavier lead been travelling a hundred fps faster they would have looked like the lighter slug does on the left. And likewise, it would have penetrated a bit less because of the greater expansion and energy dump.

Muzzle velocity - Foot Pounds Energy
240 grain - 845 fps - 381 pfe
325 grain - 745 fps - 401 pfe
350 grain - 711 fps - 392 pfe

Gel block penetration & impact speed:
240 grain - 838 fps - 10"
325 grain - 737 fps - 22"
350 grain - 708 fps - 25"