Chasing accuracy / 357 mag / LSWC's


July 30, 2010, 09:57 AM
I have been chasing accuracy on a Lee bullet for a while now and I think I came up with a zinger. It is a Lee .358 158gr LSWC with gas check and I have worked through fliers and terrible accuracy.
I tried everything in the book: 2400, Unique, H110, crimp style, casting voids, alloy changes, 4 different revolvers (3"-6"), other shooters with more experience, etc... I went from 10" groups down to 4" groups at about 20 yds shooting off a sand bag. Pretty pitifull aye? I could load any other (factory made) LSWC and shoot one hole groups off a sand bag at 20yds all day. Throw out that mold and buy another style. Not so fast... Long story short I tried seating and crimping with a Lee FCD in two steps and that bullet really tightend up the groups by a long shot. Not as good as a 158gr from MBC or OT but pretty darned good. It was not the crimp it was the post resize sqeeze it put on the bullet. Does it make sence to you? Well the last 50 I cast and sized to .357" with gas check and I can shoot much tighter groups and the occasional one hole group.
I'm not very well educated on barrel and throat slugging mathmatics but the home town self trained gun smith I paid $10 to do it claimed I should be shooting .358" (average .3584" to be exact). I don't doubt his measurements as all other cast bullets work great sized to .358".
Oh well it works.

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July 30, 2010, 12:44 PM
The first mistake you made was buying a bullet that requires a Gas Check, unless its for a rifle with a micro-groove barrel. Standard lead dia is .358" Standard load in 357mag w/158cast is 13.0gr -2400, very basic. Live and learn. :)

July 30, 2010, 12:58 PM
Forget the bore size.

Fit the sized bullets to your revolvers chamber throats.

They will slug up or size down to fit the bore.

Now, no mention of what powder charge you are using, but unless you are trying to push them to MAX .357 velocity, you will very likely get better accuracy if you leave the gas checks off the bullets.

You don't need them for mid-range .357 velocity or less.
In fact, if your alloy hardness and bullet size is correct, you don't need them period.


July 30, 2010, 03:46 PM
Yep you guys are right about the gas check bullet but it was a good thought when I bought into it. I really have no goal for this bullet but I do have about 800 more gas checks to go. So why not fiddle.
Typically I shoot a straight WW cast .358" and it works pretty well.

July 30, 2010, 03:46 PM
It took me a while, but I got mine better than I expected. Lee 158 SWC (WW) sized to .358. Tumble lubed kinda heavy, seated over 5.0gr Bullseye & a CCI 500. About every 800 rounds I clean the outside cause it looks like crap, but I haven't cleaned the barrel & just hit the 2000 rd mark with no cleaning & the riflings are still showing and the barrel looks better than my 9mm does after 50 rounds.

You will figure what it likes and you will be happier than a pig in slop when you find "The Load" it likes.

July 30, 2010, 08:45 PM
$4bill - I use a Lee flatbase tumblelube 158swc mold for 357mag(s&w 686), normally with a wheelweight alloy and water dropped.
These give me zero leading with midrange magnum loads and very minor leading at top end load levels. Which comes right out with normal after use cleaning anyway.
Using a harder (92-6-2) alloy would proberly eliminate any leading in my gun, but I don't really see it as that big of an issue and the loads shoot great.

July 30, 2010, 11:31 PM
Shoot em as big as ya can chamber em .

Unsized & I never use a FC die for revolver ammo , it down sizes the lead a little .

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