357 Mag light loads

[JohnB-40]

I'm enjoying getting to know my Winchester(Miroku) '73 carbine in 357/38 caliber. It has turned out to be a very accurate,easy handling rifle. I like the lighter cowboy action rounds for around the ranch,nice recoil and easier on the neighbor's ears. The Black Hills "Cowboy" 158gr RNFP are really accurate and real hoot to shoot,but really expensive. I hope to work up a load like the Black Hills round.

I purchased.....
357 Mag dies including crimp.and case length gauge
Trail Boss powder.
Badman Bullets 157gr RNFP.
CCI SP and SPM primers.

I reload rifle necked cartridges,but have never loaded pistol ones before. I've checked out load data online,but it is often conflicting,no one seems to even agree on whether SP or SPM primers should be used on 357M with Trail Boss. Any advise on loads using the above components to get the wanted results and things to watch for when loading straight case would be appreciated

 

[frankmako]

I use mag primers on my 357 mag match loads. I don't use trail boss powder so I can not help you there. I load 6.5 of titegroup, 158 gr hp zero bullet with mag primers for my marlin 1894 CB rifle. This is used in nra lever action pistol cartridge silhouette matches. Easy shooting load.

 

[jmorris]

I call my 357 magnum light loads, 38 special loads.

You can load the same loads at 357 OAL and they will be even lighter and not fowl the chamber because of the shorter case.

 

[Curator]

I load .357 mag brass with 4 grains of TB and the Lee .358-158 RNFP cast bullets with excellent results, The load is accurate, clean burning, and gentle to shoot. Revolver or lever action rifle, all shoot well with this load.

 

[joneb]

Trail Boss is fine with standard primers.
I reload for a Rossi 357 mag with 158gr Xtreme plated RNFP with Accurate #5 and standard primers with very good results. the charge is between 38 spl and 357 mag, Works well in a 2.75" barreled revolver too.

 

[kidneyboy]

3.7gr of Trail boss under an Acme 158gr RNFP is very good in my Henry and GP100.

 

[Walkalong]

An X-Treme 158 Gr SWC over WST or Competition for my light ".357 Mag" plinker.

I doubt it will matter much which primer you use (I use standard SP primers, never tried mag SP primers with this), but it would be easy to test out and see if one does better than the other.

 

[RedLeg105]

158gr. X-Treme SWC loaded in .357 Mag. casings with 4.0gr. of Bullseye and any SP primers, are very accurate and light recoiling loads. I've been loading them like this for years for target shooting and general plinking. According to Alliant's reloading manual this is a heavy .38 Special +P loading.

 

[reddog81]

Hodgdon lists 3.2 to 4.2 with a 158 LSWC. Not the same bullet but probably pretty close. They used a Winchester SP Magnum primer, but I'm not sure it would make a difference. the pressure ranges from 16,500 to 20,400, so you're basically looking at a 38 special +P load on the hot side of the load data. I'm guessing the 4.2 grains will almost fill the case and adding any more powder will not be advisable. I would feel perfectly fine using a regular of magnum primer.

 

[Jesse Heywood]

With TB and 158 gr SWC I tested from 3.2 to 4.1 gr. 3.2 gr did well, 3.6 gr was a tad better. That was in a sixgun.

With Trail Boss you do not want to compress the charge, pressure goes haywire. To determine your load range, fill a case to the base of the bullet. Weigh the charge, which is your max. For the min take 70%. Works for rifle & pistol. Makes it easy to develop loads.

Here's a link to the Hodgdon data sheet. https://www.hodgdon.com/wp-content/uploads/2016/11/trail-boss-reduced-loads-r_p.pdf

 

[kidneyboy]

With Trail Boss you do not want to compress the charge, pressure goes haywire. To determine your load range, fill a case to the base of the bullet. Weigh the charge, which is your max. For the min take 70%. Works for rifle & pistol. Makes it easy to develop loads.

This is how I worked up the load for the Acme 158. We also worked up a 30-30 round this way.

 

[MEHavey]

This is the "exact duplicate" of the Black Hills loads in the `73:


https://thefiringline.com/forums/showpost.php?p=6410209&postcount=9

.

 

[JohnB-40]

Thank you gentlemen for the advise in your replies. I appreciate it ME Harvey for sharing your research and load data with me,I will get a pound of W231. I agree with you about the accuracy of the Black Hills round. I fired 3 rounds resting on my Cadwell jr at target 25 yds away. Two holes were nearly touching,I thought the third was a flier,but on closeup inspection two rounds went through the same hole. I can't remember ever doing that before.

 

[brewer12345]

I use 3.8 to 4 grains of hp38 in a 38 special case in my lever, very accurate. 231 is the same powder with a different label.