Questions about Lee 105 SWCs in 357 cases

[Indybear]

After more than 25 years without a 357 I recently saw a new GP100 6" stainless at a gun show that just had to come home. I quickly ran through my old stash of around of Lee TL158 SWCs and since it is still too cold to get the pot out, I have my eyes on a coffee can full of unsized Lee 105 SWCs. I used to run these in 9mm before I switched to a 120 TC, so they are cast from an extremely hard alloy (18-20). I've loaded these in 38 cases before for other guns out of a much softer alloy and they worked extremely well but GP100 hates this combo. It has also not been nearly as good with any 38s load I've used (factory or handloaded) than 357s.

I've got 5000+ with Midway head stamped 357 brass, 9lbs of HP38, WSPs and a progressive press and I would like to make this combo work. I just sized and lubed 25 @ 358 and loaded them over 4.3 HP38 in 357 cases and I'm waiting on a trip to the range but my gut tells this is not going to work for many reasons.

My question is what are others doing? I've read many are using some form of filler to take space but that seems like it will be hard to do in a progressive press. What kind of crimp? Med to med heavy? What is a good light target load of HP38 with these 105s in 357s.

[Larry Gibson]

The problem with that light weight cast bullet in the 357 is one of case volume and a long jump to the forcing cone coupled with low mass of bullet. That translates into using a powder that is fast burning, ignites easily (HP38 does both) and builds pressure faster as the volume increases as the bullet moves forward. I found in the 38 SPL in my M15 that bullet required 4.7 gr Bullseye for consistent internal ballistics and any useable small game accuracy beyond 10 yards. That load shoots very well to 50 yards and the velocity out of my M15's 5" barrel is 1050 fps. Thus I suspect, unless shooting at close range, you will find your load is not burning efficiently. Might be a starting load but you'll probably have to work up from there and you'll find perhaps, at an accuracy load, the noise and velocity is a might more than you want. I, like most cowboy action shooters, have found that 125 gr cast bullet is about the minimum bullet weight for best results in the 38 SPL and 357 Mag at lower "target" velocities.

BTW; I did a considerable amount of R&D for a cartridge company with that bullet and VV and other powders for cowboy action loads. The 125 gr cast give acceptable accuracy at 10 yards with a revolver and 25 yards max for a rifle in either cartridge at the low velocities used. I would not consider the accuracy acceptable for small game or even plinking at smaller targets much beyond 10 yards. However, when pushed up so the powder burns efficiently (generally at 12 - 13,000 psi) the 105 can be a very good bullet. Just realize the trade off of less lead = more powder and thus more noise.

Larry Gibson

[fecmech]

I think your 4.3/hp38 is way too low. I have not shot anything that light in my GP but have used the Ranch Dog 105 gr. in my K-38. It shot well with 4.5/Bullseye and that translates to 5.3 HP38. My GP shoots very well (2-2.5"@50 yds) with 5.3/231 and the Lee 125 rnfp. If it was me I'd be looking in the 5-6 gr range of HP38 for that bullet.

[FLHTC]

I've used that bullet over 9 grains of Bullseye and in a Dan Wesson it shot extremely well. I don't think a plain base bullet being cast with 18 to 20 BHN is going to do well being shot slow. JMO You won't get any obturation going that slow.

[TMenezes]

I agree with the above, dump more powder in for a boolit that hard. Also what size are they before you size them? Try loading some unsized just to see what happens as long as they aren't massively over sized.

[220]

Ive been using the 105swc in my marlin over 5.0gr AP-50N gives around 1100fps and 1.5" groups at 50y.
Havent checked the velocity from my 6" 686 but accuracy for 10 shots at 25m is around 2.5".
For a light load I use 38spl brass with the boolit deep seated ( nose 1/10" below case mouth) 2.5gr AP-50N gives around 650fps from my 6" accuracy is great, I'm sure from a ransome rest it would keep 10 in one hole at 25m I can usually keep 9 in around 1" but usually throw one opening groups up to 1.5-2"

[Centaur 1]

I did the same thing just last week, and it worked out pretty well. I used 5.6 grains of HP-38 which is a starting load in the .38 special +P range. I am going to up the charge the next time I load some more. Those light boolits had a hard time knocking over the steel plates that I was shooting at.

[220]

Gave a mate some of my 105swc HT coated boolits to try, at 25m he had no trouble holding the 10 ring using 5gr AP-50N in his 6" python.
Gave him some of my deep seated loads in 38 cases to try, again no trouble holding the 10 ring from his python, his 4" N frame surprised with a group just over 2"

[rexherring]

I loaded a bunch of those for a friends snubbie S&W with Trail Boss. He said they worked great and almost no recoil for his wife.

[Indybear]

My light load of 4.3 of HP38 and sized 358 was like a shotgun but when ran them unsized, rolled in JPW with 5.1 of HP38 and light crimp, it was a magical combination. Accurate, zero leading after 200, light recoil and the wife loves the load. Our current range is only 50' so no idea how truly accurate these will be at range.

Thanks all