The .38 Special, Loading for Accuracy and Velocity, and Differences in Barrel Length

semperfi71 · #1 04-30-2010, 07:12 PM

DISCLAIMER: Read the disclaimer posted at the top of this forum. AND, please follow that advice and mine which follows. Use a manual, work up your loads to these levels, safely. I am not responsible for anybody's mistakes.

I post this here in case anyone might be thinking along the same lines as me.

It has been my experience, in reloading ammunition, that accuracy in a handgun can be achieved via, varying the type of powder, varying the powder weight, and by varying the bullet type, or manufacturer.

As an example, 2400 is revered by many as THE best powder in THEIR magnum handgun loads. But the reality is that sometimes, depending on the handgun, and the bullet used, other powders will produce better accuracy. And that powder/accuracy combination can vary from one handgun to the next.

So, I have a LOT of Bullseye and set about to find the most accurate Bullseye load for four S & W K-Frame .38 Specials. This required trying different 158 grain commercial cast bullets. I wanted 2 1/2 inch groups or less at 25 yards from a two-hand rest.

Here's where I ended up at:

1. S&W Model 10-7 .38 special 2 inch barrel...Colorado Cast Bullets 158 grain lead flatnose.

2. S&W Model 10-5 .38 special 4 inch barrel...Colorado Cast Bullets 158 grain lead flatnose.

3. S&W M1905 M&P 4th model .38 special 5 inch barrel...Speer 158 grain SWC lead.

4. S&W M&P .38 Special 6 inch barrel...Speer 158 grain RN lead.

I extrapolated [fancy word for "guessed"] my loads from 18 different loading manuals, and online loading data sources. Hint: you can never have enough loading manuals.

For accuracy testing I loaded 4.0 grains of Bullseye under the above mentioned bullets [and other bullets] to get the most accurate loads, which became the above listed bullets.

I guessed [not having a chronograph then] that these loads were about 800 fps velocity based on my manuals and online data, thus safe working loads. I then began to seek my "ultimate", "full" load for my .38 specials. I wanted a load that would produce close to 900 fps in any of these revolvers with their prospective bullets. CAUTION: some manuals will NOT show 900 fps attainable safely in standard .38 Special loads [not talking +P], others will.

I chose [via extrapolation again] 4.5 grains of Bullseye under the above bullets. I used a Chrony Chronograph to test my loads. I shot 10 rounds per handgun. If no velocities are shown for a full 10 rounds its because the Chrony was saying, "ERR1", or "ERR2". Which means for that shot it was not feeling well.

Here's the results:

2 inch barrel: 854, 865, 853, 822, 830, 849.
4 inch barrel: 969, 910, 946, 939.
5 inch barrel: 925, 876, 892, 900, 872, 930.
6 inch barrel: 899, 888, 942, 904, 849, 910, 920, 911.

Note that the longer barrels did not necessarily produce the faster loads. Also note the sometimes wide difference in velocities from the same handgun. NOTE: that without true pressure test equipment, one REALLY does not know how much pressure is being produced. THAT is really the important data in load testing. But since us mere mortals usually average only enough money to own a chronograph we have to go with that and the prudent, oft-repeated "signs" to look for in hot loads; flattened primers, and sticking cases. My loads did not exhibit any of those pressure signs.

Also, I "think", that most .38 Special revolvers of good quality probably will not exhibit high pressure signs until one begins to get into .357 Magnum pressure loads in .38 Special cases. As in; the size of the gun, or quality of steel [M10 vs. M19 or M586, or M27] will not be an indicator of what is a high pressure load. In essence the .38 Special case can be loaded very hot in a .38 Special revolver before it starts to show pressure. SO BE VERY CAREFUL.

SO, one must be very, very careful in working up top velocity [even though safe] standard [not +P] loads in the .38 Special. What I'm saying here is a K-Frame S&W .38 Special might be able to handle some very hot loads, BUT, if it is an older, "before" heat treatment model, or just old period, powerful loads may not be prudent. NOT even +P. AND, even a M10 from 1980 might handle some hot loads okay...but at the expense of turning the gun into as Skeeter once said, "A rattling wreck." It may not blow the cylinder out, but it may just fall into disrepair.

I am not trying to "magnumize" my .38 Specials. But I do believe that a good K-Frame or larger .38 Special can handle 900 fps 158 grain loads, especially with slower powders than Bullseye. I load my .38 Specials to this level because I hike the backwoods of New Mexico and "might" [very rare] run into a mean cougar or black bear. More than likely I will run into an enraged field mouse.

Also, if I want more power, I will carry a .357 Magnum, or even larger.

What I found out here was:

1. 4.0 grains of Bullseye in MY handguns is probably more than the 800 fps I was "suspecting". A chronograph eliminates a lot of guesswork. I have considered it a must when working up loads.

2. I think 900 fps in a S&W heat-treated cylinder K-Frame .38 Special is "okay".

3. Don't do this in a J-Frame .38 Special, ever. Keep them down in the 800 fps levels. Unless you have pressure test equipment.

I hope this helps.

H Richard · #2 05-01-2010, 02:06 PM

The Lyman cast bullet handbook shows Win. 231 and the 158 gr. RNFP as most accurate load (4.9 gr. 231) with the 158 gr. bullet. I chronographed out of my 6" 686 at 906 FPS, which is nearly exact as the book showed, and shoots 1.5" from 25 yard sandbag rest. It is not a Plus P, and I shoot in all my .38's.

semperfi71 · #3 05-01-2010, 02:43 PM

H Richard, sounds like you have a really great load. I have yet to have a handgun shoot under 1 inch [which could be my lack of ability and eyesight] but I do have ones that will print anywhere from 1 1/4 to 1 3/4. Most will go into 2 inches easy. Thanks for the input.

I do not have the Lyman Cast Bullet manual and probably should get one because a lot of manuals, especially the older ones, do not have much cast bullet data, except Lyman which in their manuals will have cast data as well as jacketed.

For a lot of data I found concerning Bullseye, 900 fps was above maximum for standard .38 Special data. Most books stopped at about 850 fps or so.

There's a lot of powders out there that will work in the .38 Special, that's why its one of our best handgun cartridges for reloading. But, I have many, many pounds of Bullseye so stuck with it. It actually shoots well in most of my handguns anyhow. I might get better groups with another powder in a handgun but the Bullseye will usually print only an inch or so larger than the most accurate powder for a specific handgun.

Hence, some of my handguns I want the maximum accuracy I can get so I will buy a can or so to use in that handgun, for others, there are "plinkers" so extreme accuracy is not necessary for my uses.

I have two M586 six inchers and haven't yet begun to wring them out. Your M686 and mine just strike me as the best 6 inch .357 made. Nice muzzle-heavy feel, stout enough to handle any REASONABLE load, and a potential for great accuracy. I can hardly wait to start working with them.