Wildly different load data

[PodPeople]

I have some Missouri Bullet Co. 158 gr. SWC bullets (their "38 Match") which I want to load as 357 magnums with Bullseye powder. For this powder the Lee Modern Reloading Second Edition book on page 528 shows a starting load of 4.2 grs. and a maximum load of 4.8 grs for "158 Grain Lead Bullet". The Lyman Cast Bullet Handbook 4th Edition shows on page 259 a starting load of 6.2 grs. and a maximum load of 6.9 grs for Bullseye (this is for their 158 grain mold #358665, a RNFP bullet). Why such a huge difference? Looking at the load data for 38 Special for the same bullet and Bullseye powder Lee on page 535 shows 3.1 to 3.5 grs. and Lyman on page 256 shows 3.0 to 3.4 grs. I am hesitant to make up the 357 magnum loads because of the conflicting load data.

[Ben]

Not really unusual to see these wide variations in loading manuals.

If you look at some of the old speer manuals from the 60's, you'll see load data with some ' ginger ' also.

The newer manuals have been toned down by lawyers.

Ben

[lka]

What Ben said, I have old books from G-Pa and new books the newer books are more Conservative, I always start out a low as they say and work it up using a chroney, it sounds like a pain but it's fun and Ives you an excuse o keep going to the range

[Jupiter7]

FWIW, the alliant website shows 4.8grs of bullseye under 158lswc for 939fps.

In comparison, the same bullet in 38spl over 3.4grs bullseye for 815fps.

Hope that helps.

[jonp]

Run into this all of the time like others do. The load data for Red Dot is all over the place. Start near the bottom and work up as always.

[mroliver77]

It depends on how much of the boolit is inside the case also. While not knowing each boolit they are different designs.
J

[Tatume]

The bullet makers claims it is not the lawyers at all. The reason loads are lighter is because they have better testing equipment, and the old loads were too hot.

One reason Lee is lighter is because they sell dippers, and the charges thrown with dippers are wildly variable until the reloader learns to use them.

[nicholst55]

The bullet makers claims it is not the lawyers at all. The reason loads are lighter is because they have better testing equipment, and the old loads were too hot.

One reason Lee is lighter is because they sell dippers, and the charges thrown with dippers are wildly variable until the reloader learns to use them.

I think its a combination of things, personally. I've read in several places that some of the reloading manual publishers didn't have ballistic labs for many years, and based their load data on notoriously inaccurate pressure signs - like we have all been taught to do. Once they finally got chronographs and pressure guns, they discovered how inaccurate their data had been - for years. I also don't doubt that their corporate lawyers have a significant influence on published data.

One other aspect that many reloaders discount is that different bullets of the same weight can create wildly different chamber pressures. This is more of a concern with jacketed bullets, but it is also an issue with cast. Just because both bullets weigh 158 grains doesn't mean that they both create the same chamber pressure with the same powder, primer, and case.

[PodPeople]

FWIW, the alliant website shows 4.8grs of bullseye under 158lswc for 939fps.

In comparison, the same bullet in 38spl over 3.4grs bullseye for 815fps.

Hope that helps.
Thanks. So Alliant and Lee agree on the maximum load but Alliant doesn't show a starting load. Guess I'll load up a batch in increments of 2 grns. with the Lee data and see what kind of velocities I get.

[gefiltephish]

The rule of thumb is that when only the max load is given (Alliant), reduce by 10% and work up from there.

[dtknowles]

I have some Missouri Bullet Co. 158 gr. SWC bullets (their "38 Match") which I want to load as 357 magnums with Bullseye powder. For this powder the Lee Modern Reloading Second Edition book on page 528 shows a starting load of 4.2 grs. and a maximum load of 4.8 grs for "158 Grain Lead Bullet". The Lyman Cast Bullet Handbook 4th Edition shows on page 259 a starting load of 6.2 grs. and a maximum load of 6.9 grs for Bullseye (this is for their 158 grain mold #358665, a RNFP bullet). Why such a huge difference? Looking at the load data for 38 Special for the same bullet and Bullseye powder Lee on page 535 shows 3.1 to 3.5 grs. and Lyman on page 256 shows 3.0 to 3.4 grs. I am hesitant to make up the 357 magnum loads because of the conflicting load data.

I expect that the Lyman load data is safe, check data for a similar weight jacketed bullet. I have not had problems using jacketed pistol bullet data for use with cast because cast bullets normally generate lower pressures than jacketed and at least it provides a couple more data points to consider. That said I would not personally use Bullseye for magnum loads in a .357 only target and midrange loads because it is such a fast burning powder and small changes can make a big difference plus the risk of a double charge.

Tim

[dtknowles]

Thanks. So Alliant and Lee agree on the maximum load but Alliant doesn't show a starting load. Guess I'll load up a batch in increments of 2 grns. with the Lee data and see what kind of velocities I get.

two tenths of a grain increments right.......:=)

[Larry Gibson]

Not wanting to get into the "conspiracy theories" regarding lawyers, etc. so I'll skip all that and get to the point;

Lyman is specific about the bullet used for the data they list. It is a cast bullet of the listed alloy and the load data is correct for that bullet.

Lee's data on the other hand is for a "158 Grain Lead Bullet" which could mean anything but more than likely refers to the soft almost pure swaged lead 158 gr .38 bullets from Speer, Hornady, Remington, Winchester and a few other manufacturers. The data Lee shows is also correct for those types of "158 Grain Lead Bullet".

Neither manual is wrong. we just need to understand what is said.

Larry Gibson

[PodPeople]

That said I would not personally use Bullseye for magnum loads in a .357 only target and midrange loads because it is such a fast burning powder and small changes can make a big difference plus the risk of a double charge.

Tim

The reason I picked Bullseye is because it is the only powder I have that I could find reload data for the 125 gr. lead bullet. Maybe I'll just wait until I can find a slower powder. I think my workflow technique minimizes the chance of a double charge. I weigh each case on an electronic scale immediately after charging and if the weight is within a tenth of a grain of my target weight I put a bullet on top of it and put it in a loading block.

[uscra112]

Watch that the zero on that electronic scale doesn't drift. Cheap ones drift as much as a full grain over time. My Pact II is better, but can still go off by a several tenths of a grain if I'm not watching to see that it regains its' zero in between charges. I do not use electronic scales for weighing powder, and especially small charges for pistols, and that's why.