38 Reloading Data Question

[338Shooter]

I have a curious. I have the newest hornady manual and was trying to load up some 38 specials for certain purposes in my new bodyguard. The bullets I have are 135gr GDHP from Speer. I don't have the speer manual, but the hornady book lists a 140 gr XTP so it should be similar. The max load for the 140 is 5.2 grains of Universal Clays and then it lists 5.3 for a +P load. Cool beans. I don't want +p and I have a lighter bullet so I did 5.1 grains of Universal for the GD. After I got all done I started digging around just to see. Hodgdon's data center lists the max standard pressure for the 140gr XTP at 4.6gr of Universal and the 14th speer book lists the +p for the 135gr GDHP from 5.0-5.2gr of Universal. So I guess I got a good +p load for my pistol.

I guess I'm wondering why my books vary so much on similar bullets with the same powder? I have the newest nosler book, hornady book, and the 37th lyman book. I also use the powder manufacturers online resources if I can. Why are they all so different sometimes?

 

[jcbarlow]

I don't have a good answer to your question but anytime you need some load data from the speer manual shoot me a PM I'll look them up for ya.

 

[338Shooter]

Thanks for the offer. I think I'm gonna switch to XTP and eventually buy the speer book. Bass Pro has them and they are cheaper than the GD at H&H. Plus they are in my book!!

If anything comes up before I get the book I'll shoot a pm you way though.

 

[Roadking Larry]

I suspect that part of the differences in loads published by different sources is due to the old ways of measuring pressure. Modern equipment is more precise and is slowly becoming standardized across the industry. I expect we will begin to see less differences between sources as time goes by. Another possible reason is some of the published data is from old "tried and true" loads that was worked up years ago and the properties of the powder has changed slightly over the years.
I always make it a habit to check several sources when working up a new load and always start at least 10% below the lowest max load for a given powder and bullet weight/type and work up from there.

 

[338Shooter]

I can't even try the min loads in any of my bottom feeders. They just won't work. I usually start in the middle for them. I also have a Lyman DPS 3 for powder measurin.

I really love my redding 3BR powder dispenser with Universal. It throws consistently. I can measure 10 in a row and never vary even a tenth on the Lyman scale.

 

[WhiteyMacD]

Differences come from differences in test items. Bullets (even though same gr weight, they are all different, gun, temperature the day tested, altitude, humidity, length of barrel used, blah blah blah).

 

[NikatKimber]

I've wondered the same thing, as the min load in one of my books for HS6 in 124 gr 9mm is actually ABOVE the max load in another manual!!

 

[MBB]

I called Alliant, Sierra, Lyman, and Hornady asking the same question. They all said the same thing: Differences in bullet bearing surfaces, ambient conditions, primers, and even the test gun's chamber dimensions will produce different results. Using older (20+ years) primer and powders and/or not the most current reloading manuals will also cause big differences because the chemical compositions of primers and powders have changed drastically over the decades.

They all recommended using the most current loading data with current components that match the loading data as closely as possible. Start at least 10% lower than the max charge listed and work your way up looking for signs of excessive pressure.

If you're really concerned, use the lowest listed maximum, start 10% lower, and work your way up to the load you like without exceeding the highest listed max charge.

 

[Shriner]

Each company use's differnat guns for testing ;4", 6" bgll 10" unvel rev. check your books and see what was used as a test gun and why one book show a load hotter another

 

[Shadowrider]

A 158 gr JHP from Sierra and a 158 XTP HP. One would think that you could load both bullets interchangeably with the exact same data. And one would be wrong. Actually you can as long as you are not at the top end of the data for the caliber you're shooting. The two bullets while weighing the same, will have different bearing lengths in the bore and the one with the longer bearing length (increased friction) is going to have a higher pressure. ETA: ---> This doesn't even address the variable of different case capacity from the differing bearing lengths.

FWIW, I've always approached reloading as custom tuning a load for you only. So in essense the manuals are only a "suggestion", or a starting point so to speak. Now if you are loading for multiple guns, you can throw this mentality out the window. Follow the manuals. But if you are down from a max load you shouldn't have any problems and even if you do, you'll not likely 'splode your gun or anything. Just another reason not to skirt the ragged edge, it makes things simpler!

With all this said I can also say that I've loaded up max loads strictly by the book and not had a single problem in any gun I've shot them in which leads me to believe that the data in the manuals are a bit conservative.