Different Starting Loads?

[Josh Smith]

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:


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

Information

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[jmoore]

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!

[Patrick Chadwick]

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

Amen to all that!