Different books, different loads, same components?

idahoducker

Getting ready to start loading for the 300 H&H so looking through my books I'm wondering about the difference here. I know each company has different barrels, equipment, etc. but I'm wondering if it's mostly just the primer in this case?

180 grain Nosler BT in Nosler #5 says 61-65 grains of IMR4350 with a magnum primer.

With the same components except for a standard primer Lyman #49 says 60-67 grains.

15 fps difference in velocity between the max loads.

Fairly big difference there in the max charge. How much would just the primer effect this?

Not planning to get to max loads, just wondering.

Rocky Raab

Is that Lyman data for a 180 Nosler or a different 180-gr bullet? Because bullet type alone can make a three or four grain difference in load data. Bullets can change the pressure that's developed by a significant amount, possibly more than any other swapped component (except powder type, of course.) A primer change can produce almost as much difference, to answer your direct question.

So when the Lyman lab loaded to the same pressure, they likely got almost the identical velocity - but had to use more powder to achieve that pressure due to the bullet's characteristics or the different primer, or a combination of the two. Make more sense now?

idahoducker

Both used nosler BT. It mostly makes sense. Just wondering if a mag primer would make that much difference. Lyman used the standard primer and 67 grains while Nosler used a mag primer and 65 grains to get the same velocity. Nosler a 24" Lilja barrel and Lyman a Remington 721 26". Each with a 1-10" twist. Interesting stuff. I'll likely use a mag primer and therefore use less powder.

Rocky Raab

Just keep in mind that it can also go the other way. Changing primers from standard to magnum or the other way can increase pressure, have no effect or lower pressure. And there's no way to predict in advance.

BTW, if you haven't read my piece on the "95% Solution" you might find it helpful. Use Firefox to keep from scrambling the pages http://www.reloadingroom.com/index_files/95S.htm

idahoducker

Haven't looked at your site in a while. I'll check it out.

MIKE WISKEY

" I'll likely use a mag primer and therefore use less powder."............it doen't always work that way, some time back I compaired loads in a .30/06 and got less vel. with a mag. primer (the only difference)

remingtongeo

Remember that Lyman uses a test barrel in a lab, not a rifle. I've found that Lyman is only good for a starting point. The best results come from books that use real firearms. The only way to know what the difference in primers and powders will do is to test with your own rifle.

JustC

chamber and barrel differences come into play as well.

Rocky Raab

The main problem with testing with "real guns" is that such guns don't provide pressure measurements. So the data developed is just a best guess at safety. With a pressure barrel cut to absolute tightest dimensions, I might not get as high a velocity from the loads shown, but I'm almost assured that I'll also get lower and safer pressures as well. I'll take that option "ever durn tahm."