Ignition Properties and Factors
Jun 5, 2020 9:22:54 GMT -5
Post by ET on Jun 5, 2020 9:22:54 GMT -5
One aspect of testing powders is monitoring the strength of the ignition and end result for performance.
To start with the strength of the ignition source originates from the BP.
There are different BP’s out there that have different strengths of ignition source. As to the difference I can’t comment on other BP’s as my experience is limited to the Savage BP. With the savage BP I did increase the flame source by recessing the vent-liner. Reducing the length of the flame channel I had to adjust the head spacing to get the deepest fit of the primer to avoid blowback.
Regardless of the type of BP used 3-factors seem to stand out.
Powder Compression
The purpose of powder compression is to reduce space between powder granules that in turn reduces flame dispersion. This forces the ignition flame to produce a stronger and quicker burn start of powder and pressure build up.
Load Resistance
This is just another way of saying how tight the load fits to the bore. So’ what role does this play?
The accelerated powder burn rate is dependent to the amount of pressure build up before bullet moves. Here load resistance helps in 2-ways. One it adds support to powder compression. Secondly the more load resistance the more pressure built before the jump start of the bullet load. This in turn influences the continued burn rate of powder. You can observe this in a PT monitoring the Rise Time.
Duplex Load
Even though I haven’t delved into Duplex Load the PT’s that TG has graciously provided tells me enough. In order to get a good burn start with a slower powder to reach a certain pressure level before the load moves a booster accomplishes this need. Eventually I will need to move into this area to obtain some of the velocities I want especially for lighter bullets. For now, I will remain with single powder loads and see how far it takes me.
For me 2-others areas I focus on are bore heat and bore cleanliness. Here I need to reproduce conditions as close as possible to the previous shot for a good evaluation of a load. These 2-factors are probably not as crucial for sabot-less but I believe they do effect sabot loads.
This is my take on what effects powder ignition. Going on the points above this will also guide me in the direction of further load testing. Just wish I could get started again soon.
To start with the strength of the ignition source originates from the BP.
There are different BP’s out there that have different strengths of ignition source. As to the difference I can’t comment on other BP’s as my experience is limited to the Savage BP. With the savage BP I did increase the flame source by recessing the vent-liner. Reducing the length of the flame channel I had to adjust the head spacing to get the deepest fit of the primer to avoid blowback.
Regardless of the type of BP used 3-factors seem to stand out.
Powder Compression
The purpose of powder compression is to reduce space between powder granules that in turn reduces flame dispersion. This forces the ignition flame to produce a stronger and quicker burn start of powder and pressure build up.
Load Resistance
This is just another way of saying how tight the load fits to the bore. So’ what role does this play?
The accelerated powder burn rate is dependent to the amount of pressure build up before bullet moves. Here load resistance helps in 2-ways. One it adds support to powder compression. Secondly the more load resistance the more pressure built before the jump start of the bullet load. This in turn influences the continued burn rate of powder. You can observe this in a PT monitoring the Rise Time.
Duplex Load
Even though I haven’t delved into Duplex Load the PT’s that TG has graciously provided tells me enough. In order to get a good burn start with a slower powder to reach a certain pressure level before the load moves a booster accomplishes this need. Eventually I will need to move into this area to obtain some of the velocities I want especially for lighter bullets. For now, I will remain with single powder loads and see how far it takes me.
For me 2-others areas I focus on are bore heat and bore cleanliness. Here I need to reproduce conditions as close as possible to the previous shot for a good evaluation of a load. These 2-factors are probably not as crucial for sabot-less but I believe they do effect sabot loads.
This is my take on what effects powder ignition. Going on the points above this will also guide me in the direction of further load testing. Just wish I could get started again soon.
