I am reloading for two rifles 9.3x64, and 9.3x62. My balistics program shows that the 9.3x64 has 63,816 psi rating, 9.3x62 has 56,564 psi rating on max. pressure. I know the reason for the difference- the strength of the actions the cartridge was chambered in.
QUESTION????????
If the rifles you are reloading for are modern (Win. 70'S), and the components you are using are new and modern, can you load the 9.3x62 to near or the same pressure as the 9.3x64??????
I have the same delema for sevral calibers---257 Roberts, 7x57, Etc..
lb404

The short answer? Yes.

The long answer involves cautions about strain gauges, chrony's, lost fingers and eyes, and marginal gains for taking all that risk. FWIW, Dutch.

Ballistics programs -- even the best ones -- use a lot of hypothetical hocus-pocus to estimate working pressures.

Barrels and components vary considerably and produce variable working pressures. You program produces a generalized estimation and NOT too reliable pressure data.

Something as insignificant as a change in primers or in powder lot will affect all your working statistics. Two identical guns will produce variations in statistics because they're produced with different tools on the assembly line.

The key to working up a load is to use a chronograph and to keep accurate notes. It's crucial that you use a large enough load string to produce a significant data sample in your chronograph tests.

Smokeless propellant generates working pressure by being ignited under pressure. Case capacity and even rifling twist can greatly affect working pressures. Pressures don't necessarily increase in a straight line increment. A slight increase in load can generate a dangerous spike in pressure -- because pressure is generated by pressure.

I wouldn't work up a load with a computer program and some pressure estimations.

For about $175, you can get a strain gauge setup that will read out in peak pressure. For about an additional $20 per rifle, you can add strain gauges to them. The gauge simply epoxies to the barrel, under the stock, and doesn't screw up your gun.

The good news is that you can accurately tell the differences in pressure between rounds.

The bad news is that getting a really accurate absolute calibration on the meter is difficult. It's kind of like having a bathroom scale that you can't exactly "zero". Still, the instrument is at least as useful as a chronograph. Just shoot several types of commercial ammo, and don't exceed the pressures they register.... or stay welll below the calibration you get by plugging dimensions into the formula they provide.

See www.fabriquescientific.com.

So,let me see if I can get it straight in my mind.
Most factory rounds are underloaded due to the fear of litigation.
Most reloading data is for loads much less than SAAMI/CPI specification due to fear of litigation.
Most chronographs can not read accurately.
HOW THE HELL DO RELOAD ANYTHING BUT ANEMIC ROUNDS?
I work up loads in my rifles the old fashion way 0.5 gr. at a time until I see things go wrong. Sticky bolt lift, primer leaks, extractor marks on the case, and finally inappropriate case head expansion. This I know, I value my eyes and hands as much as all of you.

THE QUESTION IS-----IS THE WORKING PRESSURE OF THE ROUND THE TYPE OF ACTION USED OR THE FLOW RATE OF BRASS OR SOME OTHER JUJU!!!!! I am not trying to aggrivate anyone only trying to understand why things are done this way.
Art ALPIN'S BOOKLISTS THE FOLLOWING:PEZO PSI
30-06 60,000
308 Norma 63,861
300 H&H 62,409
300 Win mag 64,000
300 Wby mag 63,861
etc.
all take 308 bullets, all can and are loaded in modern firearms, all are constructed of the same brass, why the variation in allowable pressures????????? I have two 9.3's that I worked up loads on that have been safe in my rifles and in all kinds of climates from 105 down and they are over the load limits set in the gun rags. I load for a lot of calibers that have limited loading data available for. I want to try other powders in them and still want to be reasonably safe. How do we do It?lb404

Frustrating, isn't it? Add to the list: The numbers given in books are only reasonable approximations of the pressures that happened in the chamber, when someone decided that enough was enough.

The 30-06 in particular has a lower PSI than the 270 or 308 because there are plenty of older actions out there that won't take full modern pressure. The 270 is recent enough that it does not have that problem. I am told that modern '06s will stand as much pressure as modern 270s, but I don't know.

I flinch a little when someone talks about working up, then backing down when they see "pressure signs". My understanding is that many of these signs do not appear until 70,000 PSI or so, and if you're shooting a 45-70, you're in serious trouble by then.

lb404,
The easiest way and I honestly believe the safest way is to have on hand all the reloading manuals that you can afford. I especially like: Art Alphins manual, Accurate and Hodgdons manuals because they list the pressures. Now take all of your books and look up the velocities for the particualr bullet you have. Going through the manuals you'll notice the velocities differ. Oh well. Average the max velocity for your given cartridge/bullet combo. Now you have the max velocity. Load 'til you hit that velocity. Don't go any higher. The voodoo is in reading pressure from your components. Because we have all the good metallurgy and components, you'll be way over by the time you see pressure indicated by brass flow ect.

This is my reasoning and how I do my reloading, of course you mileage may vary...