Post by Bullshop on Sept 28, 2022 18:52:07 GMT -7
We know that in the heyday of shutzen target shooting that competitors not only fired their bullets in the same sequence as they were cast but also usually had an index mark in the mold that transferred to the bullet when cast. I have often pondered the reasons for this and recently founds some answers.
First the casting shooting sequence. The reason for this is because with the lead /tin alloys used almost always poured with a ladle after first stirring the melt in the same fashion for each cast. Because the percentage of tin is so much less than the lead and the stirring for each cast caused surface oxidation the tin is being oxidized at a higher percentage rate than the lead. Because of this over a long casting session the bullets at the start will be of a lesser weight than the bullets at the end of the session.
Shooting in the order they were cast prevented bullets from each extreme end of the casting session to be fired in a group. Shooting in the order as cast kept the bullet weight consistent per group fired even though the total number of bullets produced in the casting session may have a several grain variation within the total.
As always consistency is the key to accuracy.
Now to chamber orientation of the bullet. Again consistency is king of accuracy. I learned from the book by Dr. Franklin Mann , ""The Bullets Flight From Muzzle To Target "" That they could accurately predict a defective bullets point of impact on target from the orientation of the bullets defect in the chamber and knowing the barrel length, the rifling twist rate, and the muzzle velocity. It is quite interesting that if the defect usually a groove cut into the bullet base edge is oriented consistently in the chamber then the deflection from true bore center was repeatable. When the defect was oriented 180* to the other side of the chamber the deflection was the same but on the opposite side of the target.
From this we can see why for the sake of consistency it is a good idea to orient the bullet consistently the same in the chamber for each shot in a group. If there is a consistent defect in a bullet due to an anomaly in the mold or from casting technique then consistent chamber orientation will keep the resultant deflection the same.
Its never a bad idea to take advice from those with more experience than oneself but it is far more palatable if you understand the reasons why!
First the casting shooting sequence. The reason for this is because with the lead /tin alloys used almost always poured with a ladle after first stirring the melt in the same fashion for each cast. Because the percentage of tin is so much less than the lead and the stirring for each cast caused surface oxidation the tin is being oxidized at a higher percentage rate than the lead. Because of this over a long casting session the bullets at the start will be of a lesser weight than the bullets at the end of the session.
Shooting in the order they were cast prevented bullets from each extreme end of the casting session to be fired in a group. Shooting in the order as cast kept the bullet weight consistent per group fired even though the total number of bullets produced in the casting session may have a several grain variation within the total.
As always consistency is the key to accuracy.
Now to chamber orientation of the bullet. Again consistency is king of accuracy. I learned from the book by Dr. Franklin Mann , ""The Bullets Flight From Muzzle To Target "" That they could accurately predict a defective bullets point of impact on target from the orientation of the bullets defect in the chamber and knowing the barrel length, the rifling twist rate, and the muzzle velocity. It is quite interesting that if the defect usually a groove cut into the bullet base edge is oriented consistently in the chamber then the deflection from true bore center was repeatable. When the defect was oriented 180* to the other side of the chamber the deflection was the same but on the opposite side of the target.
From this we can see why for the sake of consistency it is a good idea to orient the bullet consistently the same in the chamber for each shot in a group. If there is a consistent defect in a bullet due to an anomaly in the mold or from casting technique then consistent chamber orientation will keep the resultant deflection the same.
Its never a bad idea to take advice from those with more experience than oneself but it is far more palatable if you understand the reasons why!
