Projectile Qualification !
Posted: Fri Oct 28, 2011 11:23 am
Hi All , A number of you guys have contacted me over the years as to how and why on the bullet selection process i employ .. Well i reckon i will put it down again and hope that some will get something out of it .. This is my process and not all of it is required depending on what discipline your compete at ..
Preamble, Some research into batches and brands is required before you actually purchase a product , as simple as find someone that you can trust that has had success with a particular brand *and then try to get the same lot(batch)*
I will use my present competition bullet which is the 30 cal BIB 187gn Flat Base as an example
1 / Start with a many of this *magic Brand/ Batch * as you can afford, i like to have at least 1000
2/ pour out the whole lot and sort by weight , with a 187 that i use i batch into lots of 187.0 to 187.2 and then 187.3 to 187.5 and so on if you have to
3/ batch into lots by bullet AOL , i set this at 1.325 to 1.327 and so on ( reason i do this is so that i can Meplat them with a minimum cut )
4 / inspect with a 10 power loupe to see if there are any folds in the ogive to meplat section and any nicks in the boatail area
5/ make up a fine wire with a small 45deg bend near the tip that you can hold and then insert into the hollow point .. This is used to run around the inside of the jacket just before the lead core .. What your looking for is irregularity's in the inside surface like lumps or craters .. Any changes here and the bullet will leave the group every time
6/ Next is Base to Ogive , i segregate into 1 thou lots for std matches and 1/2 thou for big events or possibly good condition times
6a/ when getting to fine measurements like this it is important to have equipment that is repeatable, if you measure 100bullets and then a half hour later remeasure them it has to be the same or it's not worth while doing the 1st time.. The most reliable of tools i have seen offered is the comparator by Accuracy One (google it) in the US because it is so easy to influence the cheap vernier style when used by people that only pick up a vernier once a month
7/ check Bearing surface real carefull , this has the most influence in long range elevation control.. same batching as B to O
8/ Juenke them if you can or you can pretend you can win anyhow ..I like to keep my AAA bullets at less that 2 on the Juenke scale .. Bill Shehane says you can't win Shooter of the Year without one and he HAS
9/ After B to O you then need to Meplat the bullet , i like to cut the minimum off so making sure the original AOL is close will allow this.. Then recheck the AOL , don't take for granted that they will be the same (i run only bullets that measure within 1 thou (1.319 to 1.320)
10/ Inspect with 10 power loupe the meplated end and put to sighters any that don't show you two complete machined edges (in and outside jacket).. If you have bullets that need 10 or so thou removed to clean up the meplat then u need to change brands IMO
11/ depending on how good your lot is you need to double check the Base to Ogive ,but at a lesser dia .. On my bullets i check everyone at .200 dia which coincides exactly with the seating cone ( you should be able to assemble 100 rounds that measure (in total AOL) within 1 thou if thats the tolerance you used on the AOL of just the projectile
12/ Need to keep in mind that with some bullets that is is easy to get complacent with lots that are very close , but i can assure you that no matter who makes them there will be a* Bad prawn in the pack*.. I check every bullet i use even to warm the barrel , knowing that they are the same gives the confidence that it was a condition that caused the point of impact variation and not the gun
..JR..Jeff Rogers
Preamble, Some research into batches and brands is required before you actually purchase a product , as simple as find someone that you can trust that has had success with a particular brand *and then try to get the same lot(batch)*
I will use my present competition bullet which is the 30 cal BIB 187gn Flat Base as an example
1 / Start with a many of this *magic Brand/ Batch * as you can afford, i like to have at least 1000
2/ pour out the whole lot and sort by weight , with a 187 that i use i batch into lots of 187.0 to 187.2 and then 187.3 to 187.5 and so on if you have to
3/ batch into lots by bullet AOL , i set this at 1.325 to 1.327 and so on ( reason i do this is so that i can Meplat them with a minimum cut )
4 / inspect with a 10 power loupe to see if there are any folds in the ogive to meplat section and any nicks in the boatail area
5/ make up a fine wire with a small 45deg bend near the tip that you can hold and then insert into the hollow point .. This is used to run around the inside of the jacket just before the lead core .. What your looking for is irregularity's in the inside surface like lumps or craters .. Any changes here and the bullet will leave the group every time
6/ Next is Base to Ogive , i segregate into 1 thou lots for std matches and 1/2 thou for big events or possibly good condition times
6a/ when getting to fine measurements like this it is important to have equipment that is repeatable, if you measure 100bullets and then a half hour later remeasure them it has to be the same or it's not worth while doing the 1st time.. The most reliable of tools i have seen offered is the comparator by Accuracy One (google it) in the US because it is so easy to influence the cheap vernier style when used by people that only pick up a vernier once a month
7/ check Bearing surface real carefull , this has the most influence in long range elevation control.. same batching as B to O
8/ Juenke them if you can or you can pretend you can win anyhow ..I like to keep my AAA bullets at less that 2 on the Juenke scale .. Bill Shehane says you can't win Shooter of the Year without one and he HAS
9/ After B to O you then need to Meplat the bullet , i like to cut the minimum off so making sure the original AOL is close will allow this.. Then recheck the AOL , don't take for granted that they will be the same (i run only bullets that measure within 1 thou (1.319 to 1.320)
10/ Inspect with 10 power loupe the meplated end and put to sighters any that don't show you two complete machined edges (in and outside jacket).. If you have bullets that need 10 or so thou removed to clean up the meplat then u need to change brands IMO
11/ depending on how good your lot is you need to double check the Base to Ogive ,but at a lesser dia .. On my bullets i check everyone at .200 dia which coincides exactly with the seating cone ( you should be able to assemble 100 rounds that measure (in total AOL) within 1 thou if thats the tolerance you used on the AOL of just the projectile
12/ Need to keep in mind that with some bullets that is is easy to get complacent with lots that are very close , but i can assure you that no matter who makes them there will be a* Bad prawn in the pack*.. I check every bullet i use even to warm the barrel , knowing that they are the same gives the confidence that it was a condition that caused the point of impact variation and not the gun
..JR..Jeff Rogers
