what will happen if i under load a 357 shell?

What you need is some Speer shot capsules and some #9 shot for snakes. There are several powders that call for less than 5 grains for reduced loads in .357. Unique is one. 4.1 grains will get you 850 fps with a 158 grain bullet. It doesn't matter what caliber you are loading for, when making reduced loads you need to get the fastest burning powder available. No matter how it is distributed in the case a magnum primer will ignite it all at the same time. Any amount of fast burning powder will put the bullet out the end of the barrel. A magnum primer will almost put one out of a 4" barrel.

As far as detonation is concerned, loading a reduced amount of slow burning powder in a large case causes a flash over the top of the powder, forcing the bullet into the barrel and then an explosion of the remaining powder, many times causing damage to firearm and shooter.

I would not go below .38 spl load data, preferably in a .38 case (which are significantly cheaper and easier to find if you buy once fired anyway). I've heard of people using .38 data in .357 cases, but do this cautiously, yes it's only a hair longer but minimum load might not be quite enough if it has a longer barrel. Case a little longer means more room, meaning a little less pressure to propel the bullet. Probably safe, but I personally would avoid the minimum in this instance.

Try using a faster burning powder if you wish to either conserve powder or have less recoil. I've had some of my best results from a .357 using Unique, which should have a charge weight of less than what you're talking about. I use Win 231 from most of my smaller handgun cartridges, and it works well in .38 spl, and there is data available for .357. Since you're using lead bullets Trail Boss is a great powder for lower pressure loads; or else good if recoil is your concern, not so good if powder conservation is a concern since the cans are lighter due to it being so bulky.

You really don't want to go below the minimum charges as if you were to get a bullet that doesn't leave the barrel you'll have problems, especially if you don't notice and fire again.

You need to pick up some reloading manuals. Some powders are very limited to what charge you can use in a certain round. An under weight powder charge can actually be dangerous.

I don’t understand why you dont use some .38 special brass and load those 158 gr bullets in them.

Again get a bunch or reloading manuals. There are low powered cowboy action.357mag loads that recoil like a .38 special.

I do reload .357, .38 special and other calibers. But I don’t hand out load data. And if you want to be safe NEVER use load data on open forums like this. Good way to be minus some flesh and destroy the gun.

Hint look up data for Alliant 2400 powder. I use that a lot in .357 and .44 mag.

Edit;

G21.45 gave you a good answer and explained the dangers of an under weight powder load.

I suggested the 2400 powder because there are loads for it for reduced power .357, the powder fills the casing more than some other powders like Red Dot and therefore doesn’t require a filler. I have used fillers for some powders like Red Dot and Unique. I use (crazy as this may sound) cream of wheat or corn meal. In fact I use it quite a bit for some black powder cartridges because with black powder you can’t have air space or KABOOM!

You can make your own snake shot loads and there is load data for that using shot capsules and #9 lead shot. The problem with bird shot in a handgun or rifle is the rifling spins the shot creating a donut pattern with few shot in the center. Its only good out to a few feet. This is ok if the snake is just a few feet from you but is lousy if the snake is say 30 feet from you.

This isn't an entirely fair question to ask a general audience to answer - Especially when the respondents have absolutely no idea of the exact components involved. I'm going to suggest this: Open your reloading manual and and peruse all of the loadings for 38 Special through 357 Magnum. (Include the +P loads.)

I think you'll discover that, in general, you'll be duplicating 38 Special loadings in your 357 Magnum. (Which happens to be exactly how I load my 357's for PPC competition. I use the longer 357 cartridge case and a powder charge equivalent to a moderately loaded 38 Special.)

Gives me the best of both worlds: A full length case for my 357 chamber(s); and a powder charge that allows me to make very rapid follow-up shots. I literally have hundreds of 357 cartridges around here that are loaded to 38 Special specifications. You might want to do the same thing; but, I think you'd better study the reloading charts very carefully before you do.

PS: Don't load up more than one or two cylinders the first time you do this; fire very slowly, and examine the pistol carefully after every shot. Remember: When working with reduced charges you still want to fill-up the inside of the case as much as possible. (By the way, it's NOT a, 'shell'.)

eddiegordo19, you're thinking of, 'cartridge detonation'. It's what can happen to a pistol that's firing lightly loaded cartridges with a lot of air space inside the case.

It generally occurs when air gets between an ignited primer and the incendiary powder charge. Instead of igniting normally, the powder charge becomes mixed with the excess air inside the case and the cartridge, then, explodes with incredible violence.

The main reason cartridge detonation doesn't occur more often when using a fast powder in very light loads is because the gun's muzzle usually lifts during recoil and drops the powder charge back against the primer.

However, in the hands of an experienced pistolero who is firing very quickly the muzzle might not lift quite enough to cause a light charge to drop back against the primer. When this happens you'll think you were holding onto a stick of dynamite!

In addition to making sure to raise the muzzle between shots another thing you can do is to load some sort of inert material on top of a reduced powder charge in order to keep it in direct contact with the primer. I've known Bullseye pistol shooters who used everything from kapok fiber to (Ready?) oatmeal. It all works.

The danger in light loads is that the bullet doesn't make it out of the barrel and if you're firing rapid fire your barrel could explode, or at the least be ruined by a noticeable bulge when the next bullet hits the one stuck in the barrel. There is a reason for the range of powder loads, and it usually is related to safety. If it says to use 9.5 to 11 grains, then the light load would be the 9.5. You start working your loads down, you will have some serious accuracy issues. Just buy some snake shot, it pretty much is useless after 10 feet. Shoot safe.

Two problems.

One, don't "under-load" a .357 below what a .38 Special calls for, or you will have a bullet lodged in the barrel. If you reduce the powder in a .357 Magnum, you get a .38 Special.

Two, don't shoot a snake with a solid bullet, unless you want a pair of airborne FANGS that could land on you, and still bite. Use shot or a stick. When I was a damn fool kid, I shot a rattlesnake with a .44 and got to see him fly into the air. That blast lifted him up and out, sans head. Yeah, I was lucky to beat his strike, but IF I had missed, he would have had the final say. Not smart of me. Don't repeat my mistake, OK? Oh, and for the record, I was 3 feet away.

There's a safety risk in making low power loads. I can't recall exactly, but it has to do with leaving a lot of air in large magnum cases. Something to do with erratic ignition and possible case ruptures. The bottom line is you should load .38 Special loads if you want a light load.

G21.45 has given you a good answer. I'd also suggest that you might want to choose something different from your mystery propellant (you didn't name it, you know!) and not go lower than about 3 grains of Clays or 4.5 of Power Pistol.

See the last couple paragraphs. Better to buy a .22 then try to make a 5 grain 357 shell work. You would get a lot of misfires,

http://www.gunblast.com/RKCampbell_ColtTrooper.htm

http://ca.search.yahoo.com/search?ei=utf-8&fr=slv1...

I know absolutely nothing about hand loading rounds, but why would you even want to decrease the power of the bullet down that much? You want to kill a snake at 15 feet, throw a few rat shot in your pocket.