Reamer Print Question

[Crowe284]

On this reamer print, am i correct in assuming that my total overall "working length" CBTO would be 2.225"? In other words, I know that different bullets have different bearing surface lengths, base to ogive lengths, nose lengths, etc., but would any bullet be at the lands at 2.225 CBTO? In trying to visualize this, at the caliber diameter the bullet is going to hit lands no matter how long the nose, bearing surface etc. is. So, should've the total amount of "room you have to work with" stay constant? I have realized that my brain DOES NOT think well this way!

 

[Edd]

On that print, the distance from the bolt face to the .284 diameter spot of the throat is ~ 2.252".

 

[Crowe284]

On that print, the distance from the bolt face to the .284 diameter spot of the throat is ~ 2.252".

Do you mind "showing your work" on how you got to 2.252"? Thanks!

 

[Edd]

The print shows 2.045" from base to front of neck.

The print shows the step from the neck diameter to the freebore diameter goes from .319" to .2845". That is .0345". If the angle is 45°, most of them are, that will add .01725" to the length.

The print shows .180" freebore.

The print shows a 1.5° throat angle. To get from the .2845" freebore diameter to a .284" diameter at a 1.5° angle adds .00955" of length.

2.045" + .01725" + .180" + .00955" = 2.2518"

I'm guessing you are measuring your bullet at some diameter less than .284". The distance from the front of the bearing surface to the point where your measuring tool contacts the bullet will be determined by the shape of the bullet. So your measurements won't be the same with all bullets.

 

[Crowe284]

Thank you for laying that all out!