Fat bullets
- Thread starter johara1
- Start date
Alex Wheeler
Site $$ Sponsor
It would be interesting to know, but you can still get them to shoot. My lot from last season has a .2432 shank and a .2438 pressure ring, they broke every HG agg record.
Bryan Litz Ballistics
Site $$ Sponsor
This is a question for a bullet maker. I've made Eric Stecker aware of this thread and hopefully he'll be able to comment.
-Bryan
-Bryan
Raythemanroe
Bullet Whisperer
The fat ones are harder to kid nap ;D Just tagging along
Ray
Ray
Jim,
We believe the pressure ring growth is faster than the bearing surface growth for two reasons. The first is because in forming the nose, the rear of the bullet is where much of the force is realized by the bullet. (This can be proven by pointing a bullet of a smaller caliber in a larger caliber die) Since this is where the bullet is most "snug" in the die, as it is ejected this produces an amount of friction that is greater on the inside of the bullet die than the rest of the bullet.
The second reason is related to tooling. As some or many reading this thread knows, the difference in OAL of a bullet can vary from lot to lot. At this point we are unable to explain why this occurs. However, we do know that steps we take to force the material to form to the same length each time produces bad bullets.
Since the bullet OAL will vary from lot to lot, the distance that the punch goes into the die will vary slightly from lot to lot. Add to this the fact that BT punches are thin at the place where the pressure ring is found. Over time, this essentially laps the area where the pressure ring will be for a different lot. The difference in this location is not great but the affect it has on the wear in the die and the growth of the pressure ring is observable.
In a way, this subject comes at an interesting time for Berger. To address forming issues related to folding and for exploring other areas about which we are curious regarding materials affect on performance, we've hired a materials engineer who has his master's degree from MIT. We are excited about what he will be learning and applying to our process.
Regards,
Eric
We believe the pressure ring growth is faster than the bearing surface growth for two reasons. The first is because in forming the nose, the rear of the bullet is where much of the force is realized by the bullet. (This can be proven by pointing a bullet of a smaller caliber in a larger caliber die) Since this is where the bullet is most "snug" in the die, as it is ejected this produces an amount of friction that is greater on the inside of the bullet die than the rest of the bullet.
The second reason is related to tooling. As some or many reading this thread knows, the difference in OAL of a bullet can vary from lot to lot. At this point we are unable to explain why this occurs. However, we do know that steps we take to force the material to form to the same length each time produces bad bullets.
Since the bullet OAL will vary from lot to lot, the distance that the punch goes into the die will vary slightly from lot to lot. Add to this the fact that BT punches are thin at the place where the pressure ring is found. Over time, this essentially laps the area where the pressure ring will be for a different lot. The difference in this location is not great but the affect it has on the wear in the die and the growth of the pressure ring is observable.
In a way, this subject comes at an interesting time for Berger. To address forming issues related to folding and for exploring other areas about which we are curious regarding materials affect on performance, we've hired a materials engineer who has his master's degree from MIT. We are excited about what he will be learning and applying to our process.
Regards,
Eric
Eric, What i have a had time understanding is, if the jacket and lead is captive in the die and is formed how can it grow past the dimensions of the die. I know that just a change in jackets can do this but if the pressure ring is .2434 and you change lot of jackets it goes to.2438 ? Both were in the same die, does it expand after it comes out? ……… jim
Jim,
I'll say up front that we aren't certain as to why such things happen and to what extent they occur. This is one of the reasons why we are eager to get a materials engineer who can spend every day sinking there teeth into learning more about such things.
Having said that, I will tell you why I believe this occurs. First, when you describe the situation as one lot of jackets making .2434 bullets while another lot of jackets makes .2438 bullets, I'll relay that we haven't see that same thing (or at least not to that result) while the bullets are being made unless the jackets were dirty in which case you would get unusual sized pressure ring diameters but they would vary from bullet to bullet.
If I have two lots of jackets and make them into bullets one right after another we have occasionally seen the pressure ring change from one lot of jacket to another lot of jackets by roughly .0001 but I don't recall seeing or hearing about a change in the pressure ring of .0004 when going from one lot immediately following another. This much of a change would be reported as it is way outside what our set up process allows.
You asked how can the bullet grow larger than the die and my answer to that is that it can't. One other reality of bullet making that we are working to resolve is shrinkage. An alternative cause as to why the bullets you see are different by .0004 is not because one bullet got larger but because the other got smaller.
It is unknown why some bullets shrink after being formed but it does happen. When shrinkage occurs it is usually less than .0002 and it takes 24 hours for this to occur. If they don't shrink within 24 hours they won't shrink. I've heard several theories but so far we have not been able to affect this result.
I won't bore you will all the experiments and tests we've done to review this situaiton. What we do know is that bullets that shrink shoot as well as bullets that don't. This much we have proven conclusively. As to why one lot shrinks while another lot doesn't, we simply don't know yet.
Regards,
Eric
I'll say up front that we aren't certain as to why such things happen and to what extent they occur. This is one of the reasons why we are eager to get a materials engineer who can spend every day sinking there teeth into learning more about such things.
Having said that, I will tell you why I believe this occurs. First, when you describe the situation as one lot of jackets making .2434 bullets while another lot of jackets makes .2438 bullets, I'll relay that we haven't see that same thing (or at least not to that result) while the bullets are being made unless the jackets were dirty in which case you would get unusual sized pressure ring diameters but they would vary from bullet to bullet.
If I have two lots of jackets and make them into bullets one right after another we have occasionally seen the pressure ring change from one lot of jacket to another lot of jackets by roughly .0001 but I don't recall seeing or hearing about a change in the pressure ring of .0004 when going from one lot immediately following another. This much of a change would be reported as it is way outside what our set up process allows.
You asked how can the bullet grow larger than the die and my answer to that is that it can't. One other reality of bullet making that we are working to resolve is shrinkage. An alternative cause as to why the bullets you see are different by .0004 is not because one bullet got larger but because the other got smaller.
It is unknown why some bullets shrink after being formed but it does happen. When shrinkage occurs it is usually less than .0002 and it takes 24 hours for this to occur. If they don't shrink within 24 hours they won't shrink. I've heard several theories but so far we have not been able to affect this result.
I won't bore you will all the experiments and tests we've done to review this situaiton. What we do know is that bullets that shrink shoot as well as bullets that don't. This much we have proven conclusively. As to why one lot shrinks while another lot doesn't, we simply don't know yet.
Regards,
Eric
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