Hmm....Wasn't expecting that....

[DanAKAL]

4" Ruger GP100 357 Mag loaded with 158 gr SWC, 5.0 gr Unique, Winchester Magnum Primer, Mixed Brass. I put this load together for shooting Steel Challenge. I don't need anything in the magnum class of loads just for ringing steel. Something 38 special-ish in a 357 Magnum case was my goal and this seems to be it. Shoots good, no lead, and scary accurate.

Now to my condrum. I have two boolits on hand for this load. Meister 158 gr SWC and Missouri Bullet "357 Action" SWC. The Meister bullet is advertised at 16 BHN with the Missouri at 18 BHN. Testing three samples of these bullets with my Cabine Tree tester indicates they are each harder than advertised. Something in the 18 - 20 BHN range (linotype). Given the 5.0 grains of Unique in this load I expected them to significantly lead the bore of my gun. Alas, that isn't the case. In fact my bore is as clean as a whistle! Just some carbon fouling and a rifling star at the muzzle. Two passes with Hoppe's and everything is clean. I'm not complaining but this goes against traditional wisdom of a low pressure load with a hard boolit. Since I am using a Magnum primer I'm concerned that pressures are not as low as I believe them to be. The boolits each measure .358" to .359" consistently with my gun bore at .357".

I am exceptionally pleased with this particular handgun. The bore is as smooth as silk and more accurate than I am, even on a rest. I have about 500 rounds through the hand gun with 300 of them being the boolits listed here. The other 200 were Hornady HP/XTP that I used for barrel break in.

Any comments or observations on my findings would be greatly appreciated.

Dan

[Doc_Stihl]

Fit is king.
When I first started loading .357 Magnum the only commercial cast stuff available Leaded my guns profusely. Come to find out they were .356 diameter. The lube was INCREDIBLY hard and VERY dry. Looked like wax crayon mixed with corn starch.
Very hard bullets that are undersized is a recipe for leading.
In your case, it looks like you have a good fit.

[buckwheatpaul]

Doc Sthil is right...fit is the most important.....back in the mid 70's I had the same problem with .356 bullets....correct fit is paramount to avoid blow back and leading.....5 gr. of Uniquie is one of my favorite loads in .38!

[1Shirt]

Yep, fit is the key to a number of realities, with accuracy and elimination of leading at the top of the list. Prime example, most of the loading manuals list 9MM Luger as .356, and 356 will do well in most of them with cast. But with cast, in all probability, most of the 9's want .357 or .358; and some providing they will feed are loading and shooting .359 in their 9MM's.
1Shirt!

[dverna]

I used to cast straight Linotype for 148 gr match .38 bullets. Velocity was about 700 fps - no leading. 3" 50 shot groups at 50 yards. Lubed with 50/50.

I don't buy the story that hard bullets at low velocity and pressure lead.

Don Verna

[GREENCOUNTYPETE]

fit , the one place fat is good well some fat anyway about as fat as you can chamber , I run 9mm boolits in to the case with 2 coats of of alox as they fell from the mold at .360 it always swages down a bit if I pull a bullet i find they are .358 and perfect to go down my .357 barrel I use 4.5gr of power pistol and they shoot great

[DanAKAL]

Well Thanks Guys! Seems I hit on the perfect combination for my gun right out of the box. Now I know what to duplicate when I start pouring my own soon. I have everything I need to start pouring except a bench location to work from.

[osteodoc08]

As far as pressures, I'd at least run them over the chronograph and compare with other known entities.

It's all about fit.

[DanAKAL]

My Chronograph shows these with an average of two five shot strings at about 910 fps. The wrinkle in the finish here is that I am using Magnum primers. I shoot down to about -10 degrees. (Yes, that is ten degrees below zero, fahrenheit.) Henceforth, I want to stay with a magnum primer just for these occasions. The data that I find for 5.0 grains of Unique behind a 158 gr boolit does not list a magnum primer. Looking at Lee and Lyman is of little help because Lee lists Standard Primers for 357 and Lyman doesn't list Unique for 357. The one load that comes close is in the 4th Edition Lyman Cast Book under 38 Special. It shows a 158 gr Lyman boolit (358665) at 871 fps with 4.5 gr of Unique using Standard Primers. However, this load is in a 38 special case which has a smaller volume than my 357 cases. I am somewhat insistent upon using Unique for this load as I have about ten pounds of the stuff to use. Also, I want to use 357 cases as using 38 Special cases in a 357 has been a very bad experience for me. I know lots of people shoot 38's in 357's but it just doesn't work for me.

Since I have had such very good results with what I am shooting I'll load some of these with standard primers, although they are harder to come by. I'll make three loads with 5.0, 5.5, and 6.0 grains of Unique and fire them when it is below zero and see what I get. I expect that one of these three will duplicate my 900 fps velocity and probably work just as well. Only testing will tell.

[osteodoc08]

No issues with magnum primers so keep on keeping on. Looks like you have a good combination. -10F is seriously cold for me. Hope you're wearing gloves!

I use magnum primers when I have no regular primers or am looking for that last bit of accuracy (which may or may not improve with mag primers) They are "mandated" with 296 for good ignition. I have tons of them lying around as that's my favorite magnum pistol powder.