.38 Special load in a .357 Magnum case for subsonic use

[cpy911]

Howdy!

My favorite .38 special load of 4.6 gr Unique under a 158gr RNFP boolit shoots wonderful in my suppressed Rossi 92 levergun. It stays subsonic and the sounds of the boolit hitting the target are louder than the air gun sound the rifle makes. However, my Rossi does not like to feed .38 cases very well. I would like to load the same load in a .357 magnum case, but my load book says 6.0 gr is the minimum. I got daring and tried a load with 5.5gr Unique under the 158gr boolit and it was supersonic in the 16" barrel.

My question is, what would happen if I dropped down to 5gr of Unique in a .357 magnum case under a 158gr boolit? Would it be safe, or would I have some weird detonation? I think 5gr or so under a 158gr boolit will keep it subsonic.

Here is the video of me having a blast, no pun intended. https://www.youtube.com/watch?v=n_AoomzWwSw

I hope someone on here knows if it is safe. I am wanting to load down about 1gr from what the manual says.

Thanks!

[fecmech]

Nothing will happen other than you 4.6 load will be a few FPS slower out of the mag case.

[cpy911]

Thanks. I will bump up my 4.6 load a little in the .357 magnum case and see if it still stays subsonic. I just didn't want to risk detonation with a smallish charge of 5gr in a .357 magnum case. I assume Unique burns fast enough to reduce a detonation issue?

Nothing will happen other than you 4.6 load will be a few FPS slower out of the mag case.

[Cowboy_Dan]

If all else fails, a little dacron, used properly, will trick the powder into thinking the case is smaller.

[gwpercle]

The 5.0 grain load in 357 case should just about duplicate 4.6 in a 38 special case. Unique has no small charge detonation problem. Don't worry about about that. Unique does require a certain amount of pressure to burn cleanly and completely. 4.0 grains was about the lightest, clean burning charge I could use in the 38 special, after that I found 700X, Bullseye, and Red Dot worked better for light "target loads" but I tried to use Unique for them for a while before giving in and getting a faster powder.
Let us know how it works out,
Gary

[runfiverun]

Gary has about the same advice I would have.
except the use of a magnum primer may help, it does in my lower velocity swaged bullet load with unique.

[jonp]

The 5.0 grain load in 357 case should just about duplicate 4.6 in a 38 special case. Unique has no small charge detonation problem. Don't worry about about that. Unique does require a certain amount of pressure to burn cleanly and completely. 4.0 grains was about the lightest, clean burning charge I could use in the 38 special, after that I found 700X, Bullseye, and Red Dot worked better for light "target loads" but I tried to use Unique for them for a while before giving in and getting a faster powder.
Let us know how it works out,
Gary

^^Mirrors what I have found along with runfive and the mag primers. I would try both spp and spm. My target loads in 357 use a faster powder, Promo/Red Dot mostly

[cajun shooter]

What about trying a powder such as Trail Boss that would fill the 357 case? Just a thought, and I'm a BP shooter so if it's a crazy idea, please excuse my lack of Ballistic training with smokeless powder.

[TCFAN]

I use 4.2 grs. of Bullseye powder in 357 case with my S&W 686 for bullseye one hand target shooting. Velocity is 850 fps, average out of my 6 inch barrel. It is very clean burning.If Unique proves to be to dirty burning at lower charges you might look at the Bullseye powder.....Terry

[Outpost75]

+1 on the 4.2 grains of Bullseye as a ".38 Special Equivalent" when loaded in .357 brass!

I use this in a BSA-Martini cadet rifle with soft lead 1:30 tin/lead, plainbased 180-grain flatnosed bullet, and it averages 1050 fps and is very accurate. In my Ruger Blackhawk with 4-5/8" barrel it gives 855 fps.

Attachment 141979

[fecmech]

What about trying a powder such as Trail Boss that would fill the 357 case? J

IMO no real need to. Small charges of BE give very uniform ballistics in big cases. In my 30-30 with a 150 gr. cast bullet and 7 grs of BE I get 1272 fps,es of 22 fps and sd of 6 fps. That is a 10 shot string with no attempt to position the powder,just remove from box and shoot!

[cajun shooter]

I've loaded tons of BE in my 68 years with over 15 of that as a Range Officer and Firearms Instructor for a Metro Police Force of 1200 officers and I'm very familiar with it's burning characteristics.
I was answering the question from the point of view that the OP was looking for a powder that would fill the case and be a safe load. Later David

[fecmech]

I was answering the question from the point of view that the OP was looking for a powder that would fill the case and be a safe load.

The OP never mentioned trying to fill the case, only saftey of the load in a mag case.

please excuse my lack of Ballistic training with smokeless powder.

I was only responding to your post, I thought you were unaware of BE's ballistic uniformity in large cases.

[cpy911]

Unfortunately, I only have Unique to work with. There is still a shortage of all pistol powders in my area and Unique is all I have.
IF I ever see BE for sale, I will buy a pound and try that too.

The OP never mentioned trying to fill the case, only saftey of the load in a mag case.


I was only responding to your post, I thought you were unaware of BE's ballistic uniformity in large cases.

[jonp]

You only have Unique? I could live being stuck with that as my only powder.

[cpy911]

Yes, this has been my sole pistol powder that I first ever started reloading with. I have even reloaded 30-30 with it for a mild plinker load too. It is good stuff that works for many applications.

You only have Unique? I could live being stuck with that as my only powder.

[45-70 Chevroner]

Unique, Unique, Unique. I use other powders but unique is my favorite. Light loads of Unique in 357 cases are quite safe, just don't go too low or you will stick a boolit in the barrel.

[rak1]

Is anybody using HS6 in a light target load.

[243winxb]

Powder Position Sensitivity- Powder forward or back may make a difference in velocity, resulting in a stuck bullet in the barrel. I would guess, Unique is not one of the problem powders ?? http://www.thehighroad.org/showthread.php?t=607180 Note the very low velocity in the data.

[warf73]

Up until recently I used 357mag case ONLY using either red dot or herco running 38spec fps with great accuracy.
The red dot load was
3.X grains
Lee 150gr round nose(sized .359"),
mix lot of 357mag cases
WW small pistol primer
Never ran this load across the chrony but would guess 800~850fps.

Herco load
6.Xgrains
Lee 150gr round nose(sized .359"),
mix lot of 357mag cases
WW small pistol primer
Never ran this load across the chrony either but would guess 950~1000fps.

Both loads were very easy to shoot in long range sesions and accurate out to 25 yards using S&W 627

Never used Unique but just found several loads ranging from 4.X~6.Xgrains using a 158gr lead boolit. With FPS ranging from 800~1200.
If you can pick up a Lyman loading manual, or almost as good a RCBS lead casting book (small hard back book) it has nothing but lead loads a great source for reloading cast boolits.