Burn Rate VS. Speed (Pressure)

[Waskawood]

I am working on a cartridge for which there is no reloading data available. I have been fire forming some brass and have been using a combination of powder, primer, and bullet that give me 3650 fps with no visual signs of pressure. If I change the powder to a faster burn rate and adjust the quantity to give 3750 fps will the pressure remain close to the same as before? All other components remaining the same. It is a 17 caliber cartridge so 3650 fps isn't smoking hot.

 

[Joe R]

IMO if you change powder you should start from the beginning and work your way up.

 

[Waskawood]

Joe, I completely understand that. If you stop and think about it, there is no data available so I have to go back and start low to find what will give me a safe round. My question is and I repeat. When I find that amount of powder that gives me 3650 fps will the pressure be close to what I had before. I guess to try and simplify my question can a chronograph be used to indicate pressure to some extent?

 

[CatShooter]

I am working on a cartridge for which there is no reloading data available. I have been fire forming some brass and have been using a combination of powder, primer, and bullet that give me 3650 fps with no visual signs of pressure. If I change the powder to a faster burn rate and adjust the quantity to give 3750 fps will the pressure remain close to the same as before? All other components remaining the same. It is a 17 caliber cartridge so 3650 fps isn't smoking hot.

No...

If the case is NOT full and you are getting 3650, you can increase the amount of powder (I know, that is obvious )

But if the case is full and you are getting 3650, without obvious signs of pressure, you must go to a faster powder in order to get more velocity.

Doing so will give you more pressure. It is unavoidable.

 

[CatShooter]

I guess to try and simplify my question can a chronograph be used to indicate pressure to some extent?

No... a chronograph will not give any indication of pressure. Learn to read primers and cases for pressure.

 

[Waskawood]

Thank you gentlemen. I appreciate the help.

 

[searcher]

It is my understanding that any time a faster powder is used to arrive at the same velocity with the same projectile, pressure will be higher because the pressure curve is faster.

 

[asauer]

Somewhat off topic, but still related- has anyone else noticed loads may be listed that average around say xx.x grains = xxxx velocity and 62,900psi for example with a 50 grain bullet. Well with that exact powder and a different weight bullet, they may stop at xx.xx grains, xxxx velocity, and only 61,300psi. Does this mean only maybe 0.1gr more powder resulted in a severe pressure increase?

I doubt it, but always find it curious. I guess maybe the technicians gathering data don't bother to bump powder charges until pressures are very consistent across bullet weights?

 

[Nvreloader]

What case in that 17 caliber??????

Tia,
Don

 

[Waskawood]

What case in that 17 caliber??????

Tia,
Don

It is a 22 TCM necked down to 17 caliber, neck turned with a 40 degree shoulder.

 

[Nvreloader]

Waskawood

I know that case,
I have been doing the same thing,
just attempting to find the perfect rifle for it, etc.

If you don't already know about it,
drop in at,

http://www.saubier.com

There is load info there and us guys ONLY play in these small caliber etc.

Tia,
Don