Missouri Bullet .38 DEWC's in .357 Mag?

[fishhead1]

Have a box of Missouri Bullet Co. .38 DEWC's (.358 Diam) that I bought for .38 Special target loads. However, was considering using them for .357 Mag light target loads as well. Got to looking into the technical issues and see that their .38 DEWC's are manufactured to a Brinell Hardness (BHN) of 10. Using the handy equation in MB's Technical section for figuring optimum BHN's, it appears that I won't be able to avoid leading in my S&W Model 19 using any of the recommended powder loads I have found for similar weight LWC's. So was wondering if anyone has tried this particular bullet for .357 applications, or should I forget it.

[joneb]

I have loaded 148gr cast DEWC for .357 with good results using 3.2-4.0gr of Bullseye or 3.4-4.4gr of W-231 all seated to the crimp groove leaving about a 1/10th of inch protruding, with a light roll crimp. These DEWC's were not Missouri cast bullets but their BHN was 10-12

[Unclenick]

Seated flush with the case mouth, the DEWC's seating depth (how much bullet is inside the case) is much greater than an LSWC's. That leaves much less space for powder to start burning in, so it raises the pressure of any given charge weight. In other words, loads safe with the SWC will not be safe with the DEWC seated flush with the case mouth.

This is part of an on-going problem with load modern load manuals. Long ago they would list seating depth instead of COL. That got beyond most people's ability to do simple arithmetic, so they started listing COL. The problem, assuming your bullets are not seated out so far they touch the lands of the rifling (impossible in a revolver) is that seating depth is what matters to pressure for a given bullet weight. As the manuals are organized now, they make it appear that matching bullet weight is all that determines pressure for a given powder charge.

It's not!

To get the exact same chamber pressure from a given powder charge, the following bullet characteristics need to match:

Projectile weight
Projectile construction (thick jacketed, thin jacketed, lead, solid, saboted, etc.)
Projectile length
Projectile bearing surface length
Projectile seating depth
Projectile diameter
Projectile lubrication, where applicable

It's more than most of us want to deal with, so we normally just reduce charges 10% to get starting loads. In the case of the wadcutter seated, flush, though, it isn't enough because the case volume change under the bullet is so great.

When you calculate the effect of wadcutter seating depth on usable case capacity under the bullet, you'll find the 158 grain LSWC 0.69" long seated to 1.590" COL has room under to hold about 16 grains of water in a .357 Mag case, while a 148 grain LDEWC 0.58" long flush-seated leaves only about 11 grains of water volume under it. The rule of squares is only for changes of 10% or less, and in this larger span says charges would be reduced about 17%. Running some maximum pressure loads through QuickLOAD, I find that 20% reduction is closer. As a practical matter, allowing for powder differences, I would reduce maximum loads given for the LSWC by 25% for the LDEWC and work up, watching for pressure signs.

For a target load with the LDEWC's in .357 cases, try 3.0-3.2 grains of Bullseye with a taper crimp for longer brass life before mouth splitting. That works fine for me. The recoil isn't enough to unseat bullets from the taper crimp in any of the revolvers I own. If your guns are very light, YMMV.

As to leading, that's another issue. You have read the various pressure estimating values correctly. Be aware they are empirical and apply to bullets sized 0.001" over groove diameter. You can shoot much harder bullets can be fired without leading if they are sized 0.002" over groove diameter because that is enough to ensure a bore seat without depending on upsetting the bullet to fill the bore.

That said, over the years I've found the condition of the firearm usually has more to do with leading problems than the bullet specifics, so long as the bullet doesn't start out smaller than groove diameter. In a revolver it is critical that the chamber throats be at least half a thousandth bigger than barrel groove diameter. Slug the bore and slug the chambers to make sure this is so in your gun? If not, the cylinder can be removed and sent out for reaming. Ruger will do cylinder reaming free on their guns if you send them the whole gun with an accuracy complaint, but the postage costs exceed that of simply removing the cylinder and sending it by itself by regular carrier to cylindersmith.com, who will do the reaming for $37 last time I looded.

Revolvers not uncommonly have a constriction in the rifling where the barrel screws into the frame. That has to be removed by hand lapping or by firelapping before leading can be minimized. Indeed, if the bore is not uniform, the muzzle must be the narrowest point, or lead bullet accuracy will be seriously diminished and leading will tend to be be severe. In other words, a uniform bore or a bore that tapers slightly narrower approaching the muzzle is fine. A uniform taper to a half thousandth narrower at the muzzle is generally agreed to produce maximum lead bullet accuracy. Any other combination than straight or progressively narrowing taper down toward the muzzle makes a mess due to gas blow-by that cuts lead unevenly from the bullets, unbalancing them, and deposits it in the bore.

Correcting bore constrictions by firelapping tends to create that desirable taper condition and typically increases accuracy, often quite significantly. BHN 10 bullet hardness is suitable for firelapping and you might devote some of them to the process if your slugs show the bore has constrictions ahead of the muzzle? It can also correct chamber constrictions, but that won't be quite uniform if the chambers aren't uniform. If you are going to get the chambers reamed, save it for after firelapping.

Another factor is whether you cylinder locks up with the chamber well aligned with the bore. If it does not, a gunsmith can correct it, provided the frame is not twisted.

[jmortimer]

This is where the Laser Cast 148 grain DEWC from Oregon Trails would be nice in a .357 as it is hard-cast - You could drive it to 1,200 fps - not "soft" like Missouri Bullet

[LeadHead]

I use both the 148 dewc and the 158 swc in 357 cases. I have had good results with these loaded just a touch hotter than 38 special loads with Bullseye powder. Leading doesn't seem to be an issue. Fired out of a Smith 66 6".

[bluetopper]

I just chrono'd some today......

357 Mag cases
148gr DEWC, 17 brinell hardness, bullet out to crimp groove
6.2gr Universal Clays powder
1,283fps

6" S&W model 686-3

[RedHawk357]

Thanks for taking the time to put together such an informative post. Certainly gives me some things to consider.

[jmortimer]

He do know a whole lot and is nice enough to share good info.

[bluetopper]

Yeah, he do.

[RedHawk357]

Bought 500 DEWC off of Reloaders Auction from Seller Illinois Bullet for 29.00. He claims a BNH 15 IIRC. Tested with Universal, 2400, Titegroup, Bullseye,and HP38. For the powders I tested anything over 1000fps leaded for me. In the past I have been able to just clear 1500fps with Daradas 158 grn SWC and 2400 with just a faint trace of leading (10 rnd test sample).

Parasite, I quit with Universal at 5.5 grns and had a fairly good amount of leading did you find the same results?

[bluetopper]

No, I didn't see any leading. Barrel looks clean and shiney.

[RedHawk357]

Thanks I might reshoot a couple with a little less crimp and see if I still get the leading. I just recently got a couple Lyman M expanders and Redding profile crimp dies. Might have over crimped.

[bluetopper]

My 148gr DEWC bullets came from Two Alpha bullets and I highly recommend them. I've put 12gr of 2400 behind them and my barrel came out clean.

Also I have been very fortunate I think, but I have not experienced any leading even in full house 44 Magnum loads with various powders. I buy these bullets from a vendor on gunbroker.com, "JKFAB". They are wonderful bullets, and the cheapest I have found. I just ordered some of his 158gr SWC and can't wait to try those at top 357 speeds.

[salvadore]

My limited experience with lead bullets tells me that hardness, up to a point, isn't as important as how size relates to the throats and groove diameters. I shoot wheel weight metal in just about everything I have and get little to no leading. The great thing about the DEWC is you have a nose pour bullet with a perfect base is you load the sprue up.

[fishhead1]

Thanks for the good inputs, folks. Guess I'll load up a few with a little Bullseye (about 3.0 gr to start with) and see how she goes.