Conversion factor of 1,422

[Jim 44-40]

Need some help! If I have a load with 11,400 Pressure C.U.P   Should the BHN be 8 ? Thanks in advance

[BCB]

Jim 44-40,

I believe that conversion number works for P.S.I. not C.U.P.  Ain't sure though, but BHN of 8 can surely handle 11400 C.U.P. I feel certain.   Good-luck...BCB

[LAH]

If you do 1422X8=11,376 then you certainly want nothing harder than 8 BHN for your load and perhaps somehting a little softer would be better.

[Jim 44-40]

Thanks guys, had time to do some math. To change C.U.P to Psi take Cup x 1.516 + cup=(____)-17,902=Psi .

[TennesseeNuc]

Can someone explain the use of 1,422 as a conversion factor?  I think it has to do with the bullets ability to upset and fill the bore, but I don't know how to use it.
Thanks,
TnNuc

[BCB]

TennesseeNuc,

You are indeed correct that the conversion number has to do with the bullet obturating, that is, the base being "smashed" to fill the rifling fully and allow for a good seal as the bullets travels the barrel.  An example of its use is:  Pretend you cast a bullet of BHN 10.  You multiply that times the conversion factor and you get 14220 P.S.I. to obturate the bullet.  If you are shooting a reload that produces 12000 P.S.I. the bullet may not obturate.  If you are shoot a reload that produces 15000 P.S.I. the bullet, in theory, will obturate.  
I think this is just a guide and not an absolute.  Good-luck...BCB

[TennesseeNuc]

BCB,
Thanks for the info.  I'll make a note and keep it in mind while casting and loading.  If I don't write it down I'll forget it. :?
Best,
TnNuc

[Graybeard]

Thanks guys, had time to do some math. To change C.U.P to Psi take Cup x 1.516 + cup=(____)-17,902=Psi .

Wrong oh! There is no such thing as a converstion factor. There is just no true relationship between the two means of measuring pressure. Some times CUP is higher than PSI for the same load and cartridge. At other times it's the other way around. Other times still they are almost identical. It varies too much to try to state any fixed relationship cuz there is not fixed relationship between them.

[Smokin Joe]

I agree with the Boss, where in the heck did you find that conversion factor? There's a big difference in measuring the length of a copper crusher slug and reading PSI from a strain gauge. I think you can toss the formula.........the sooner the better.

[Jim 44-40]

From ShootingSoftware.com

[Graybeard]

From ShootingSoftware.com

Then that's as good a reason as I can think of to not spend anymore money there or to believe anything else they tell you.