high pressure formula

[jdwilson0906]

All max charges are based on the max OAL. Does anyone know how many grains to add to equal book pressure with say every .005th of longer OAl. I know its usually trial and error to get to right load. My personal loads i load to the nat hair but friends that i will be loading for i wont make .001 off the lands and it would be nice to know by math how to match my own pressures in there guns with a little shorter oal.

[PawPaw]

All max charges are based on the max OAL

Max charges are based on pressures obtained in a lab with a pressure fixture. It doesn't even look much like a rifle, but it shoots ammo and the companies are able to trace the pressure curve.

The basics of handloading remain the same for every rifle. Reduce all recipes by 10% and work up each load for a particular rifle. If you're not willing to do that then you're flirting with danger. Each rifle is different, even two of them with consecutive serial numbers and each handload has to be tailored for each individual rifle.

We old-timers have learned that some loads work better across the board than some others. I've got one .308 load that shoots extremely well in every rifle I've ever shot it through, but it's not a max load, to the contrary, it's what many would consider a starting load.

There is one load that I've used that's not a max load in the book, but exhibits over-load characteristics in my particular rifle. I'm still two grains under the book max, but I get flattened primers and a sticky bolt. That particular load is an overload in my rifle.

Don't flirt with excess pressure. It's not worth it. Work up each load for each rifle and don't shoot anything that's been reloaded by another hobbyist. Tell your friends to follow the same rules.

[reloader28]

I loaded the Lee FN 44 mag bullet at both seating depths to see the difference once in my pistol.
The difference between the lower crimp groove and the upper is about .08".
It took 2gr more powder when I seated it long to get the same speed as when it was seated shorter.

Whether this means anything or not, it takes a certain pressure to hit a certain speed. Again, this was in a pistol, not a rifle.

[Brian Pfleuger]

Does anyone know how many grains to add to equal book pressure with say every .005th of longer OAl.

.005 is a very small amount and the difference is likely very close to zero but the actual space "opened" by extending the bullet .005 will be dependent on the exact cartridge.

For example, extending the bullet .005 in a 32acp makes a difference of about .006cc, which is only about 1%. The same change in a 50BMG makes a change of about .017cc, which is only .09%.


In other words, you'll never know the difference. The difference in distance from the landes will have a far more drastic effect on pressure, as will the difference in chambers from one gun to another.

[wncchester]

"All max charges are based on the max OAL."

Really?


"Does anyone know how many grains to add to equal book pressure with say every .005th of longer OAl."

No, it doesn't work that way. IF it were possible every loading manual would list it. And wouldn't that actually work contrary to your first observation?


"I know its usually trial and error to get to right load."

Well, it's not "usually", it's always. On that "nats" thing, it would be helpful to know if you're talking about rifles or handguns. ??

[dahermit]

All max charges are based on the max OAL. Does anyone know how many grains to add to equal book pressure with say every .005th of longer OAl. I know its usually trial and error to get to right load. My personal loads i load to the nat hair but friends that i will be loading for i wont make .001 off the lands and it would be nice to know by math how to match my own pressures in there guns with a little shorter oal.

Put just one in the cylinder, spin it, close it, close your eyes, etc., etc. Those who play Russian Roulette with pressure will usually learn the error of their ways. As all the hand loading manuals say, "Start with the lowest load for the powder you are using...". And stop when you find an accurate load! Load for accuracy, not pressure. Safety is everything.