Different Starting Loads?

Hello,

I start my handloads using, of course, the minimum load.

I'm aware that below minimum can cause pressure spikes.

My question is this: Different sources list different starting loads. For example, I like Varget. When loading for the 7,9x57J, I go first to Hodgdon Powders' data. They list, for a Hornady 150grn soft point bullet, a starting load of 45.5grns for a velocity of 2561fps and a pressure of 37.5K CUP.

Now, I flip over to Sierra and their load data says 45.1grns to start. Granted, different bullet with different bearing surface, but it also has a longer COL. Same weight bullet though.

Now, I go to Hornady's load data and they list a starting load of 43.5grns for a 2400ish feet-per-second. I like that -- but why the 2 grain discrepancy between the powder and bullet manufacturer?

I tend to think the powder people know their pressures and such the best so I go with their data before the bullet peoples' data, but it still leads to some confusion.

On top of everything else, my bullet is this:

https://www.milsurps.com/images/impo...24_40849-1.jpg
Buffalo Arms - Product Detail - .318" Dia. 150 Grn. Spitzer Jacketed Bullet - $37.00


It's made by Buffalo Arms Corporation and appears to have about the same bearing surface as the Hornady, so I load and watch for pressure sign.

Is this the correct procedure?

Should I be doing anything differently? How does one go about getting data for bullets not listed?

Any other advice?

Thanks,

Josh

Check the data for different cases, primers, and whether they worked up their loading data using a specific type rifle vs. a "universal receiver" with a test barrel. Lots of variables. Whilst not specific to your case, Hornady bullets, such as the .44s are actually bigger than everyone else's- 0.430" vs. the usual 0.429" and there load data is a bit different too. Other factors- Jacket thickness, Ogive form (secant vs. tangent), Powder lots, Chamber throat geometry...Just compare some reliable data and either pick one that best matched your situation or find a happy medium from which to start.

As far as generating loads for unknown components, ummm--- ain't gonna do it! I have my own thoughts and techniques, but nothing that I feel safe sharing. Like building a 25-35 WCF load using Nosler ballistic tips and seeing how fast I could reasonably push them. Completely outside all the boxes!

Quote:

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Originally Posted by jmoore

As far as generating loads for unknown components, ummm--- ain't gonna do it!

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Amen to all that!