Bullet diameter/concentricity

[SteveOak]

What is the best way to measure the concentricity of the diameter of a bullet at various points along the bearing surface?

I am sourcing some new bullets and would like to evaluate enough to assure myself that the manufacturing/production process is adequately controlled for diameter and concentricity.

I could use a mic but that would be a bit tedious for more than a few bullets and still not thorough. A dial indicator set up something like the Sinclair concentricity gauge would measure run out but not absolute diameter.

I looked online at the Sinclair site and didn't see anything that looked promising.

 

[Canadian bushman]

Are you looking for concentricity or roundness?

 

[SteveOak]

This would seem to be the way to measure concentricity. Now how to measure diameter at several points in an efficient manner.

 

[Jim Hardy]

What is the best way to measure the concentricity of the diameter of a bullet at various points along the bearing surface?

I am sourcing some new bullets and would like to evaluate enough to assure myself that the manufacturing/production process is adequately controlled for diameter and concentricity.

I could use a mic but that would be a bit tedious for more than a few bullets and still not thorough. A dial indicator set up something like the Sinclair concentricity gauge would measure run out but not absolute diameter.

I looked online at the Sinclair site and didn't see anything that looked promising.

I use the Accuracy One concentricity gauge with a dial indicator that reads to .0005 -- very expensive but the best on the market. I find this tool mandatory as a bullet maker and bullet modifier. BTW, it has many other functions as well. Check out the videos on this tool.

Jim Hardy

 

[LR Hunter]

Why not just use Berger bullets and not worry about it?

 

[SteveOak]

Berger does not make a bullet that has the terminal performance that I require.

 

[6MMsteve]

T Rex

 

[SteveOak]

A 55 pound plate of AR500 to be knocked off a stand at 500 meters.

Bullets of typical lead/copper construction tend to expend most of their energy turning to dust and not transferring their energy to pushing over the plate.

Even if you could stand the recoil for a 40 shot match I have seen a 308 and 30-06 fail to knock the plate over.

 

[wapiti25]

a 250 gr .338 Berger will knock it over out of a 338 win mag. 7mm 08 with 160+ bullets have worked in the past.

 

[SteveOak]

a 250 gr .338 Berger will knock it over out of a 338 win mag. 7mm 08 with 160+ bullets have worked in the past.

Magnums are not permitted by NRA rules. Not that it would matter, only an idiot would attempt to shoot a 40 shot match with a 338 Win Mag.

7-08's with various weight bullets from 150 to 180 gr also fail. I have seen it happen repeatedly.

 

[mikecr]

Juenke machine. For measuring bullets themselves, this is the ticket.

 

[SteveOak]

I have looked at a Vern Juenke Machine and considered buying a kit. They are quite interesting. My understanding is that it does not actually quantify the dimensions of a bullet, rather it compares the rotating mass of one bullet to another bullet. This is helpful in determining out of balance conditions due to voids or eccentricities.

 

[JRS]

Juenke machine. For measuring bullets themselves, this is the ticket.

Right

 

[SteveOak]

Right

What results do you get with one? Please provide units of measure.

 

[Jet]

Tag--I'm interested in the response for the Juenke

 

[mikecr]

It's Air-coupled ultrasonic measurement that simply reads in 'Deviation Units'.
I believe it shows combined jacket thickness variance and air gap variance (from any bullet runout).
It's very sensitivehttps://www.deepdyve.com/lp/spie/air-coupled-ultrasonic-measurements-in-composites-dFKYoE2MjH

 

[JRS]

It's certainly sensitive

 

[rardoin]

It's certainly sensitive

I prefer an E-meter...I have the local Scientology group audit all my bullets