Question on Proof Marks

[furyous68]

Thought I'd pose this question for all you smithies...

Got a 1979 Italian made Sharps rifle. Here are the proof marks on the barrel:



The one in the middle is a "Gardone & Brescia Definitive Proof for Guns w/ Smokeless Powder".

I was under the impression that these should be used only with black powder loads, or reduced smokeless loads- like cowboy action loads.

But, it seems it was tested for smokeless. Does this mean I can shoot standard smokeless loads from it? Should I tear it down farther & see if the same stamp is on the receiver somewhere?

Thanks for any info. Here's a little more Sharps porn:

[kcstott]

well just because it rated for smokeless don't mean it's rated for 65,000 PSI.

Not knowing the caliber doesn't help. But i'll give you an example,

the 45-70 has three different smokeless loads,
Trapdoor loads at a max pressure of about 18,000 Cup
Lever action and falling block of up to 26-28,000 cup
then you have Ruger loads and those are as hot as the brass can handle

the lyman 47th handbook has the data
I'd buy loads rated for the 1886 Winchester and 1895 Marlin and nothing hotter.

[furyous68]

Sorry, should have provided the caliber. It is 45-70.

Previous owner pretty much only used his own BP loads, or light loads (equal to BP) using IMR 3031.

I'd buy loads rated for the 1886 Winchester and 1895 Marlin and nothing hotter.

So something in the 26-28,000PSI range?

[kcstott]

Sorry, should have provided the caliber. It is 45-70.

Previous owner pretty much only used his own BP loads, or light loads (equal to BP) using IMR 3031.



So something in the 26-28,000PSI range?

No that's PSI. I said CUP. not the same thing. Be careful with that as you can get in a bad situation reading PSI as CUP

Based on my formula for conversion that puts you at 20,000 psi

the best formula I can find is PSI= CUP X 1.51586 -17902
or CUP = PSI +17902 / 1.51586

like i said if you buy loads get them for 1886 winchester or 1895 Marlin loads

if you build loads it's the second section in the lyman book for the 45-70

look for loads in the following ranges

300gr @ 1650 FPS =23,000 CUP
350gr @ 1450 FPS =20,000 CUP
405gr @ 1400 FPS =20,000 CUP
500gr @ 1300 FPS =24,000 CUP

These velocities are approximate and conservative, Older weapon should be treated with a good deal of respect

[furyous68]

My bad. You did say CUP, not PSI. I just learned about those early yesterday, need to train myself to not interchange them.

Thanks for all the info. I'm starting to get a better picture on all this. I'm picking up a reloading book today, either a Lyman's or Hornady, and studying it this weekend.

I'm kind of laughing right now. Was worried about the box of ammo I bought. But when I called the mf'r, they told me the rounds were 9900CUP. Sounds like they'll be just fine. I am going to reload for this rifle... too expensive not to.

[kcstott]

My bad. You did say CUP, not PSI. I just learned about those early yesterday, need to train myself to not interchange them.

Thanks for all the info. I'm starting to get a better picture on all this. I'm picking up a reloading book today, either a Lyman's or Hornady, and studying it this weekend.

I'm kind of laughing right now. Was worried about the box of ammo I bought. But when I called the mf'r, they told me the rounds were 9900CUP. Sounds like they'll be just fine. I am going to reload for this rifle... too expensive not to.

Sounds like those are trapdoor loads and will be just fine. gentle but fine.

Both of those book have the data in them for the various loads for the various actions. just remember CUP is always higher than PSI

[furyous68]

Gotcha. Thank you for your insight. I'm sure I'll be back with more questions.

[kcstott]

Gotcha. Thank you for your insight. I'm sure I'll be back with more questions.

That's what we're here for. Feel free to PM