S&W 340 questions

[historicfirearms]

I want to load up some defensive type practice rounds for my 340M&P in 357 mag. I've got some of the 135 grain gold dots as well as some 158 grain cast Lee RNFP and am trying to choose a powder that will, 1. work well (decent velocity) in the short barreled snuby to simulate the factory 357 loads, and 2. have low muzzle flash for shooting at night. Anybody recommend a powder that will meet these two goals. I want to do some simulated night defensive shooting to make practice as real as possible but I don't want to break the bank by shooting factory ammo.

My other question is more theoretical. My 340M&P has a scandium frame and stainless steel cylinder. There is a little stainless blast shield in the frame that stops flame cutting from gasses in the cylinder gap. Apparently scandium is very prone to damage by hot gasses. The S&W 340pd (scandium frame and cylinder) is only rated for bullets over 120 grains when fired with 357 mag. I read somewhere that the lighter bullets let too much gas past while it is jumping the barrel/cylinder gap. Now, I believe that S&W knows what they are doing, but I can't wrap my head around the logic. I am thinking that a light bullet would be loaded (factory) with a faster burning powder and so the powder should mostly be burned up by the time the bullet jumps the gap. It seems like a heavier bullet, loaded with a slower powder, would still have powder burning as it jumped the gap and allow more gas to escape at the gap. This assumes that the factory ammo is loaded with different powder for different bullet weights. If they use the same fast powder for either heavy or slow bullets, then I can see how a heavy bullet with more inertia would have a more complete combustion as it passes the gap. I know this is being really nit-picky, but hey, I bet someone else on this sight has already thought this through. I'd like to hear your theory.

[DaveCampbell]

FWIW: I have a 340 M&P that I often carry as a pocket pistol. It would take a lot of empirical evidence to convince me that the increase in velocity in this barell length would be critical in the performance of this revolver as a self-defense weapon. In other words, I'd need some very convincing evidence that the increase in recoil and muzzle blast would make a real difference in the capability of this revolver to save my sorry rear end.

As I see it this revolver is an eye-socket gun--something I would use to shoot a perp in the eye sockets in order to get me out of an unpleasant situation. That means it is a me-and-you gun--a three- to five-yard self-defense gun. At that range the difference in velocity and its effects between a .38 +P and a .357 would be negliable IMHO. So I just carry factory 125-grain Gold Dots and go on my merry way. For practice, my regular handload with a 148-grain wadcutter is sufficient.

Just my pair of pennies....YMMV.

Dave

[imashooter2]

There is no such thing as low flash in a 1 7/8 inch .357 magnum. Load your 158's with the book loads of Bullseye, Unique, W231, etc. and you'll have fine mid velocity practice rounds.

[2ndAmendmentNut]

I carry and shoot frequently my little 649 j-frame. It is the stainless steel one with the shrouded hammer. Honestly for a gun with no barrel or sights worth mentioning I have always been surprised by how well it shoots.

Now to your questions...

I have loaded bullet weights from 110-200, with powders from Bullseye to H110. I have also fired a good number of these loads in low light. They all make a pretty good flash simply because of all that powder burning outside the barrel. I believe the closest thing to what you are looking for is a heavy 190-200 grain Boolit such as Ranch Dogs 358-190 with small charges of Trail Boss.

Just in case you are interested my go to powder is 2400, and my projectiles are always cast.

[historicfirearms]

DaveCampbell - I agree that the J-frame is a close range gun, in fact any gun I concealed carry will probably only ever be used at arms length. I traded in my S&W 442 for my 340M&P wanting the extra energy of the 357. Most people can't shoot the full power magnum loads in the lightweight j-frames without a lot of practice. That is why I want to come up with a cast load that duplicates the factory full power loads.

2ndAmendmentNut - I shoot my J frame alot too. With my 38 spl cast loads they are really accurate once you learn the sights. I can hit my 12X12 steel plate at 100 yards almost every time, my friends can't believe it when I pull out a gun from my pocket and start hitting steel. I like the idea of the heavy boolit but haven't tried them. Do you think I could duplicate the feel of a full power 125 grain factory magnum load with them? Sometimes I think that the heavier boolits generate more of a "push" rather than the "snap" of the lighter boolit. I agree with you that all the magnum loads in a snubby are going to be pretty flashy, but I don't think it is exactly why you are thinking. Even in a magnum rifle, almost all of the powder is burned in the first two inches of the barrel (assuming proper powder charge and type). In a 357 round I would guess that all of even the slowest powder is burned before the bullet leaves the barrel. What we are seeing as muzzle flash is just the hot gasses escaping into the atmosphere, where they experience exponentially lower pressure immediately. Powder manufactures put in chemical flash suppressants in some powders to hide a lot of this, but I agree that in a snub barrel you will never get no flash.

[Walt]

Ramshot Silhouette is a medium burn rate, low flash, ball powder (improved Winchester WAP) that would make some good medium power 357 loads with your Gold Dots. Full house loads in a 340 are just not fun for practice. I ran a cylinder full through mine and I'll not do that for practice again. It's like having a handfull of angry bees. :mrgreen:

[MtGun44]

Just FYI, the frame is NOT scandium. It is aluminum alloy with a bit of scandium which makes
it much stronger than most aluminum alloy frames. S&W hypes the scandium because nobody
ever heard of it before. My bet is that it is under 2% of the alloy.

I have a 342 which I like a lot, but would not even consider firing .357 Mags in a gun this
size and weight. I have no doubt the gun will take it, but my hand is unhappy enough with
heavy boolit and moderately hot .38 Spl loads, no need to go farther.

Also, I believe the cyl is titanium on that, not stainless steel. IIRC, S&W says to never scrub
the cyl with metallic brushes, only nylon - the titanium has a thin, hard coating that you do
not want to scratch or remove. Maybe they made some with SS cyls, but I thought that
was a different model number.

http://castboolits.gunloads.com/picture.php?albumid=161&pictureid=3952

This load works extremely well for me, and is accurate and hits where the sights look. I
found no other load (after spending a bunch on expensive self defense ammo) that shot
very accurately and none that shot to the sights. Penetration in ballistic gelatin is twice
what I get in saturated phone books, so expect about 10" to the front of the boolit in
ballistic gelatin. Your .357 mag is more capable (velocity-wise) but the recoil must be
horrendous. I have a 329 and even with full power loads, it doesn't hurt my hand like
the 342 with med hot loads.

Bill

[Walt]

Also, I believe the cyl is titanium on that, not stainless steel. IIRC, S&W says to never scrub
the cyl with metallic brushes, only nylon - the titanium has a thin, hard coating that you do
not want to scratch or remove.

Bill

The "M&P" 340s use a stainless cylinder.

[subsonic]

I want a top-fuel funny car I can drive to work too.

You are going to have to accept compromises here. I would suggest that if you really want .357s, you should look at AA9 or Ramshot Enforcer for powders and try some projectiles around 140gr.

I like shooting big bore revolvers, and I am glad my scandium pocket gun is a .38spl. I would rather shoot my .500JRH with 440gr boolits going 1300fps+ than my 337ti with 158gr +P+ .38s.

A load I am playing with for mine is the Lee 105gr SWC over some 700x for practice. I chose this so that it shoots somewhat close to the same POA as my carry loads, which will be some sort of 110-125gr JHP and so I can start to learn how to shoot this this thing well without icing my hand afterwards.

But in all reality, I usually just slip my G20 on. It is much more capable than a 5 shooter pocket gun. The more I shoot them, the more I don't like tiny, lightweight carry guns. They give up lots of performance for convenience.