bullet sorting and seating

[jwp6114]

bullet sorting...
I just started sorting by bearing length to further reduce my extreme spreads, already anealing, about the only thing I'm not doing yet is trim & point meplats. I am shooting Berger 6mm 105's
I am sorting pills in lots of .003 (I.E. .319-.321 then .322-.324 ect), my question is has anyone ever done any testing to see velocity variation average differences with .002 .003 .005 or .010 ect bearing surface length differences?


bullet seating...
My next question in my quest for low (single digit) ES'S has to deal with bullet seating, ok less jump = more pressure and vice Versa,
To my knowledge there is not a seating die on the market that pushes on or near the bottom of the ogive or nearest the bearing surface, but they all seat from a random point on the ogive (not consistent seating depth)

What are your thoughts?

 

[jwp6114]

any thoughts?

 

[oldfatguy]

Way too much thinking for me. But if it makes you happy - why not.

OFG

 

[JGorski]

bullet sorting...
I just started sorting by bearing length to further reduce my extreme spreads, already anealing, about the only thing I'm not doing yet is trim & point meplats. I am shooting Berger 6mm 105's
I am sorting pills in lots of .003 (I.E. .319-.321 then .322-.324 ect), my question is has anyone ever done any testing to see velocity variation average differences with .002 .003 .005 or .010 ect bearing surface length differences?


bullet seating...
My next question in my quest for low (single digit) ES'S has to deal with bullet seating, ok less jump = more pressure and vice Versa,
To my knowledge there is not a seating die on the market that pushes on or near the bottom of the ogive or nearest the bearing surface, but they all seat from a random point on the ogive (not consistent seating depth)

What are your thoughts?

Just my 2 cents but I think you're wasting your time meplat trimming and measuring the ogive with berger bullets, they're that good/close. The Bergers I have the meplat looks as good as it's going to get. I did meplat trim my Nosler and Hornady bullets, though, and sort them for ogive length.

 

[P7id10t]

bullet sorting...
I just started sorting by bearing length to further reduce my extreme spreads, already anealing, about the only thing I'm not doing yet is trim & point meplats. I am shooting Berger 6mm 105's
I am sorting pills in lots of .003 (I.E. .319-.321 then .322-.324 ect), my question is has anyone ever done any testing to see velocity variation average differences with .002 .003 .005 or .010 ect bearing surface length differences?

If you're that good that a few mils off a bearing surface make the difference in your shots, I would recommend you also rent a high speed digital camera (50,000 fps or more) and photograph the bullet leaving your barrel and you can look for the bullets which exhibit best stability leaving your barrel. I would speculate those which have the least accuracy would also not jibe with the harmonics of your barrel and exhibit an inherent wobble or something like that.

bullet seating...
My next question in my quest for low (single digit) ES'S has to deal with bullet seating, ok less jump = more pressure and vice Versa,
To my knowledge there is not a seating die on the market that pushes on or near the bottom of the ogive or nearest the bearing surface, but they all seat from a random point on the ogive (not consistent seating depth)

What are your thoughts?

Pop out the bullet seating cup from your die, and machine a new one out of aluminum that matches your bullet so force is applied across a much larger bearing surface.
I have found if my bullet seating force surface is too small, it will leave a optically perceptible indent in the bullet -- one you cannot feel but can see in the light reflecting off the bullet.
Speculation: In theory, a cup with a "morse taper" would work well where the tangential force engagement would happen just above the bearing surface. However if the taper is not aggressive enough, the bullet will wedge in the cup and when you retract the press, it will pull it right back out.

 

[oldfatguy]

It is pretty easy to use a bullet and lapping compound to lap the seating cup to match your bullet's exact contour. Chuck the seating cup it a lathe or drill and hold the lapping compound smeared bullet against it while it turns. It does't take much to knock the dead sharp edge down to where it no longer leaves a mark on the bullets.

OFG