Healthy Respect for Pressure
Mar 9, 2022 18:40:08 GMT -5
Post by ET on Mar 9, 2022 18:40:08 GMT -5
We utilize pressure for the driving force in our SML’s to accelerate our bullets to a desired velocity. The key component for pressure is the powder we use. Secondary components are the strength of the ignition source and weight of the bullet whose rate of movement provides volumetric spacing to help regulate the pressure build up. This is the basic concept that happens in 1.5-2 milliseconds. So now it boils down to using said components in a way to keep the pressure to a desired level for achieving our velocity goals for a particular weight bullet.
Powder burn rate can be a confusing terminology because the rate of the actual burn can be altered say with the ignition source. There are a few different designs for choice of BP for hotter ignition than say the Savage BP. But what they appear to lack is a flame channel that also acts as a pressure reservoir to reduce the pressure that the primer will be exposed to. If there is direct exposure to bore pressure, I agree that bolt lugs should be considered as a precautionary measure.
What I find interesting is the response of slower burning powders seen on a pressure trace. The Rise Time to peak pressure is slower and so is the pressure decay behind the bullet. The rate of acceleration is dependent on the amount of pressure behind the bullet. Hence slower powders produce higher velocities. But a possible down side of slower powders is that peak pressure is achieved further down the bore. Something to consider if using a high-pressure load with slower powders.
Being hunter orientated shooting a max of 200yds I feel the velocities I want to achieve can be done under 40K. For those that shoot higher pressures they have bigger kahunas than I do, chuckle. To each his own.
This post is intendent only to be informative and not dissuade anyone of their SML goals.
Powder burn rate can be a confusing terminology because the rate of the actual burn can be altered say with the ignition source. There are a few different designs for choice of BP for hotter ignition than say the Savage BP. But what they appear to lack is a flame channel that also acts as a pressure reservoir to reduce the pressure that the primer will be exposed to. If there is direct exposure to bore pressure, I agree that bolt lugs should be considered as a precautionary measure.
What I find interesting is the response of slower burning powders seen on a pressure trace. The Rise Time to peak pressure is slower and so is the pressure decay behind the bullet. The rate of acceleration is dependent on the amount of pressure behind the bullet. Hence slower powders produce higher velocities. But a possible down side of slower powders is that peak pressure is achieved further down the bore. Something to consider if using a high-pressure load with slower powders.
Being hunter orientated shooting a max of 200yds I feel the velocities I want to achieve can be done under 40K. For those that shoot higher pressures they have bigger kahunas than I do, chuckle. To each his own.
This post is intendent only to be informative and not dissuade anyone of their SML goals.