What to do when bullet mold not listed in published loads?

[JNG3]

Been doing a lot of reloading for my Ruger 38spl LCRX and my 357 mag GP100 lately. Would like to try a bullet in my LCRX that I've been casting for the GP100. It is a RCBS .38-150-swc. This mold strongly resembles the Lyman 358477. Problem is that neither of my manuals show much in the line of swc's in the .38spl. If this was a center fire rifle and jacketed bullets I would just carefully work up a load looking for signs of high pressure. Can't really do that in a 38spl. Gun will grenade before most of the classic high pressure signs show themselves. So here's what I've got-

Rem cases
Fed small pistol match primers
RCBS 38-150-swc bullets weigh 154 grs on average and are cast from 20-1
Have Bullseye, Unique, and 2400

Anyone care to recommend a load?

[acoop101]

If the bullet truly weighs 154 grains any 158 grain load data will be safe.

Sent from my XT1565 using Tapatalk

[Nueces]

Nearby weights offer a starting point, as acoop101 says. Maybe more important in general is seating depth. Reducing the pre-ignition powder space by deep seating will raise pressure even if the bullet weight is the same as listed in your manual. Thus, deep seated full wadcutter loads must take this into account.

[Kraschenbirn]

If you've got an older edition of Lyman Cast Bullets Handbook, you can use data for the 358430 (150 gr. RN) or, from a more recent edition, use data for the 358091 150 gr. WC.

Bill

[Charles Ellis]

From the RCBS Cast Bullet Manual #1-- The only powder on your list that they give data for is Bullseye--4gr to 4.5gr.
Other listed loads are--4227-11.6gr to 12.6 gr-----H110 9.7gr to 10.7gr.----2400 9.2gr to 10.2gr.----231 4.5gr to 5.0gr
Good luck with the project.

[Yodogsandman]

Stick with Bullseye or Unique. 3.0 gr Bullseye is the listed starting load for a 158 gr Lyman 358665 SWC, with 3.4 gr being the maximum load per the Lyman Cast Bullet Handbook #4. A 3.0 gr load of Bullseye is very popular load. Unique starting load is 4.0 gr to 4.5 gr max load. 2400 is not listed for this weight boolit, probably not listed because of +P pressures.

When you can't find the load listed for that boolit, go up to the next higher weight boolit listed and start at the listed STARTING loads.

[Scharfschuetze]

I've used that RCBS boolit for years. Any safe load for a 158 grain boolit will be fine with it. I've had great results in both the 38 Special and moderate loads with the 357 Magnum (apx. 1,100 fps) using that boolit. Any of the normal or common fast to medium pistol powders will work well.

For years I just used straight clip on WWs with the design with perfect performance. I now add a little tin as the latest WWs seem to be deficit in Sn.

By the way, RCBS published a cast bullet hand book several years ago. You might find one on E-bay. It has our design in it. If you have some specific questions, post and I'll look it up for you.

[Shiloh]

They frequently aren't. Find something similar and develop a load from there. LEE 175gr. .325 8x57 Mauser has no data. There is a 165 gr. load listed. I used the starting load and worked up.

Shiloh

[dragon813gt]

It's called load development for a reason. If all you want to do is load to a recipe than stick w/ jacketed. I'm not trying to be harsh. But this question is asked frequently.

[runfiverun]

the rcbs book is within arms reach.
in the 38 it shows with a 4" barrel
2.0-2.5 for 231 and bulls-eye 525fps to 720
and 2.1-2.6 for 700-x 650-800
2.3-2.8 for PB which is basically imr's green-dot 650-800 fps
you could work up from lymans data for the 477 if you want to try something else.

[rintinglen]

Between 1980 and 1999 I shot about 10,000 38 specials loaded with that boolit, RCBS 38-150 KT allegedly 150 grain though mine generally ran 3 or 4 grains heavier from wheel weights. Every one was shot over 5.0 grains of Unique, which was the powder and charge recommended by Elmer Keith for his 358-429--worked great. A man with only one mold to choose from could do a lot worse.

I also ran a few score 357 magnums with 15.0 grains of 2400 with the same boolit, but found leading to be a problem so most of my 357 magnum shooting was done JHP's or 358-156 GC boollits.

But more generally, when confronted with finding a load for a boolit for which there is no published data, there are several paths to follow. Regardless of which you choose, start at the bottom and work up. Your goal should be an accurate load that functions well in your gun, not to set some new velocity record. Hot loads break guns.

First, if there is a similar weight jacketed bullet listed for your cartridge, you can use the starting loads for the JHP projectile and be reasonably assured that as long as your boolit profile isn't too dissimilar from that of the JHP and you load them the same OAL you will be safe. If you have a chronograph, you then run ten or so across the the sky screens and see how your velocities compare. If they are equal to or less than the published velocities for the same powder charge, you can feel free to increase the charge until you get the accuracy you want.

Now if for some reason, you see that the book velocity for 5.6 grains of Wonder X is 822 fps and you are getting 863 fps for the same charge--slow your roll. Although 41 fps doesn't sound like much, the rule of thumb is a 5% increase in velocity means an increase of at least double that in pressure. As long as you started at bottom, you should still be safe. Most published charts have at least a 10% difference in pressure between top and bottom, with most more like 15-20.

Second, if there is published data for a similar weight cast projectile, especially if they are of the same basic design, feel free to use the published data with your substitute. For example, maybe you have an Old Modern Bond boolit that looks like a 311-41 but isn't an exact duplicate. You can use the Lyman data and as long as you don't red line it, you can be sure that you will be safe. Stay a grain or two under the published max and blaze away.

Third, if there isn't a published load for anything close to your boolit's weight, go to the next heavier load. Say you have a 44 boolit that runs 230 grains and is a round nose. Lyman publishes loads for their 429-383, a 246 grain round nose boolit. Use that data and feel safe do so.

Somewhat similar is the method for determining a safe load with a powder that is not listed for your particular cartridge and boolit. In 2012 I found myself out of ww-231, one of my main stays. More problematic, my stash of 38 Spl wadcutters had run out. It was time to improvise. The only powder I could find that was remotely akin to it was titewad. There was no published 38 special info for that powder at that time. So I entered into uncharted waters, warily. First, I looked at the comparitive burn rate charts to see what it was close to. Now one thing to be aware is that the fact that two powders are near each other in the chart does not mean they are equally distant. New York to Philadelphia to Saint Louis to Honolulu is one way to look at east to west cities, but while they may run east to west, they are not equidistant. Likewise, powders may be sequentially numbered in the burn rate chart, but still be pretty different in burn rate. Still, that gives me a place to start.

Titewad is down there with the very fast boys. Only Norma R1, Alliant E3, AA Nitro 100, and Vitavouri 310 are faster. Well, r1 has been out of production for a good many years, but VV-310 seemed likely, but no good--they had no load data for it for 38 special. But I did find some data for AA Nitro 100. A recommended charge for AA Nitro 100 for a 158 grain LSWC was 2.4 to 2.7 grains. The max charge was only 16, 250 psi.

Now my boolit is a 142 grain H&G 50 WC. But By looking at the two loads and comparing them to loads for Bullseye for a 158 LSWc and a 141 grain WC, I started at 2.2 grains and went up to 2.4 grains where I stopped. I had the accuracy I was looking for, more or less, and the recoil and velocities were at levels where I felt certain that my pressures were low. My Chronograph crapped out while I was doing testing of velocities, bu the data I did get seemed to affirm that I was safe.

Perhaps a bit long winded, but these are the methods I have used to identify safe cast loads for my revolvers and pistols, as well as my rifles..

[JNG3]

For those who suggested that I didn't want to work up a load and to just use jacketed bullets, well if I wanted easy and jacketed bullets I would not be on this forum.

I have been loading button nose wadcutters using a Lee mold and Bullseye for the 38spl. Of course the manuals don't call for that exact bullet. I used the data for two very similar button nose EC's that were of comparable weight. Worked up a very nice accurate load. Now with the SWC, the only swc load listed in my manuals uses the Lyman 358156. I was concerned with seating depth differences, dissimilar number and style of lube grooves, and the fact that is looks to be a gas check design. Did not want to assume that using the data for that Lyman bullet would be OK. Assumptions lead to problems. Thanks to all who offered help. I will start with Unique at 4 grs and work up from there.

[vrh]

Ditto on the load data for 358091 150 gr. WC. It's in the Lyman Cast Bullet Handbook.