Slowly Coming Together
Sept 25, 2019 7:37:40 GMT -5
Post by ET on Sept 25, 2019 7:37:40 GMT -5
Because of this post containing some theory and unproven facts (for now) I thought this post was better suited here. Also a lot of other factful help issues being dealt with on SML board.
The overall question is “What makes SML function as it does?” Surprisingly there are numerous factors that influence SML performance. Generated gases move and accelerate a moveable obstruction we call bullet-bullet /sabot. Now the one component that is most influenced is choice of powder and how it’s used. Normally we follow given load recommendations and simply pour the powder into bore and place our bullet load on top. Okay but how many of us apply some kind of compression on the powder.
Savage feels this was important enough to mention in their 10ML-II Quick Tips under loading. Here is the excerpt.
Consistent ignition and velocity for the smokeless powders listed, depends upon the sabot/bullet being seated with enough force (30 to 40 pounds of pressure) on the ramrod to compact the powder charge. Best accuracy is achieved when the same amount of seating pressure is used on the ramrod for each and every shot.
This suggests to me that by compression we reduce spacing between the grains for better ignition and burn.
Next up is the ignition source from a primer. Now I see there has been development of different style BP’s for aiding of a better ignition. My focus for now is on the Savage BP. The Savage BP has what is considered a long flame channel from the powder. Here IMO energy is lost before it reaches the powder. To compensate for this loss the flame channel length needs to be reduced for a higher energy output. Hence my choice for a recessed BP.
Now by recessing a BP we also create a smaller entrance chamber when powder is first ignited. Here the oncoming hot gas/flame is limited to its dispersion because of chamber size. IMO this produces a better burn start for the powder. As to what degree of influence for different size diameter recesses is yet to be determined, hopefully through PT testing that will be revealed.
Hopefully I’ll get some answers eventually to questions even with the slow process of getting PT results.
Ed
The overall question is “What makes SML function as it does?” Surprisingly there are numerous factors that influence SML performance. Generated gases move and accelerate a moveable obstruction we call bullet-bullet /sabot. Now the one component that is most influenced is choice of powder and how it’s used. Normally we follow given load recommendations and simply pour the powder into bore and place our bullet load on top. Okay but how many of us apply some kind of compression on the powder.
Savage feels this was important enough to mention in their 10ML-II Quick Tips under loading. Here is the excerpt.
Consistent ignition and velocity for the smokeless powders listed, depends upon the sabot/bullet being seated with enough force (30 to 40 pounds of pressure) on the ramrod to compact the powder charge. Best accuracy is achieved when the same amount of seating pressure is used on the ramrod for each and every shot.
This suggests to me that by compression we reduce spacing between the grains for better ignition and burn.
Next up is the ignition source from a primer. Now I see there has been development of different style BP’s for aiding of a better ignition. My focus for now is on the Savage BP. The Savage BP has what is considered a long flame channel from the powder. Here IMO energy is lost before it reaches the powder. To compensate for this loss the flame channel length needs to be reduced for a higher energy output. Hence my choice for a recessed BP.
Now by recessing a BP we also create a smaller entrance chamber when powder is first ignited. Here the oncoming hot gas/flame is limited to its dispersion because of chamber size. IMO this produces a better burn start for the powder. As to what degree of influence for different size diameter recesses is yet to be determined, hopefully through PT testing that will be revealed.
Hopefully I’ll get some answers eventually to questions even with the slow process of getting PT results.
Ed