Bought a new S&W M&P 340 CT a few weeks back. Also bought a box each of the Speer 38+p and 357 mag Speer short barrel loads that use the 135 gr Gold Dot bullets. These are designed for the short 2" or less barrels.

I wanted to duplicate the factory velocity so I could practice my BUG draw from my front left pocket so I bought 500 of the bullets. On hand I already had all the Federal 38 and Remington 357 cases I could use along with CCI 500 sm pistol primers. You'll note I'm not using mag primers in the 357 mag since I'm not using the large charges of slow burning powders.

First thing was to check the velocity of the factory loads. With my CED M2 chrono set @ 15' from the muzzle I ran 10 rounds each through the 1.875" barrel of the little S&W.

38+p = 860 fps
357 mag = 990 fps

I then proceeded to try several powders I had on had. You may notice I didn't try the extremley slow powders such as H110, 296, etc. They might have achieved the desired velocity but accompanied with the attenuating muzzle blast and flash.

I used two sources for load data; Hodgdon and Steve's reloading pages which in on-line. Of course I'm not taking responsibility for your reloading practices so be careful, use good safety precautions and work up.

I've listed what I came up with as a max charge right after the charge I used. (Ie, "5/6" means I loaded 5 gr but 6 was what I determined to be the book max charge)

Here are my results of 5 shots over the chrono

38 Special...............

Universal Clays - 6/6.5 gr = 865 fps (promising)

700x - 4.2/4.1 gr = 706 fps

Titegroup - 4.7/4.6 gr = 775 fps

HS-6 - 7.1/7 gr = 694 fps

Power Pistol - 6.4/6/4 gr = 799 fps

I did not fully pursue the 38+P as I felt I could tolerate the velocity of the 357 mag.

357 Mag.........................

700x - 5/6 gr = 779 fps

HS-6 - 9/10.5 gr = 842 fps

Universal Clays - 6.5/7 gr = 882 fps

W231 - 6.5/7.7 gr = 829 fps

Titegroup - 6.3/7 gr = 926 fps
Titegroup - 6.8/7 gr = 976 fps

Solo 1000 - 6/7 gr = 921 fps
Solo 1000 - 6.5/7 gr = 944 fps

Power Pistol - 8.6/9.6 gr = 965 fps
Power Pistol - 9/9.6 gr = 1021 fps

As you'll note, I felt the last three powders were the most promising and retested them, looking for that little extra velocity. I had a 3rd round of loads loaded up and ready to run over the chronograph but at the range my CED M2 chrono would not work, no matter what. It was sent off to CED two days back. Once it is returned, I will complete the testing and let you know the results.

I feel Solo 1000 will be "the" powder. Not because the velocity but because of the potential for zero/little muzzle flash. By that I mean that several years back I tested 1/2 dozen different powders in my 1911 defense loads and the Solo 1000 not only gave great accuracy and the desired velocity but very importantly it gave zero to little muzzle flash. One night I took my video camera and filmed myself shooting in the dark and the Solo 1000 was the best of the lot.

As for shooting the pistol. When I first received it, I took with me to the range, what ammo I had on hand to wring it out a bit. Ouch! But that is because besides the two factory boxes I bought, all I had was a few hundred rounds of something I put up over 20 years ago for a LARGE 6" N-frame M28. They are a 170 gr Lyman cast bullet from mold #358429 over a health charge of 2400 in 38 cases. They hit 875 fps in the short barrel of the little M&P 340. I also forgot to bring my PAST shooting gloves. I won't make that mistake again. The factory Speer loads were quite sedate but I still would not practice with out the gloves in place.

Also, shooting strong hand (right for me), I found I needed to keep my strong thumb pointing straight towards the muzzle. If I curled it down, wrapping it down and around the frame, the bottom edge of the cylinder release would peel some skin off my thumb. Fortunately for me, I mean to carry and shoot this thing weak handed in my front left pants pocket and it wasn't a concern.

Enjoy!

Alan