Measuring a reamer freebore

[Alex Wheeler]

I posted this the other day but that thread is gone. I thought I would put it up because it may help someone save some grief. This is a quick easy way to verify that your freebore is close to what it should be. I can usually get within .005" of the true length doing this. Which is close enough for freebore length. This one is a .140". So if you come up with .130-.150 and the print says .140, it probably is. This will tell you if something is far enough off to cause an issue.

 

[Nvreloader]

Alex
Thank you for posting this info,
now I'll double check my reamer.

Tia,
Don

 

[nakneker]

Helpful!

 

[Nvreloader]

Alex
Question for you,

What if there is NO parallel section shown (like your photo shows),
and there is only a straight taper from the neck mouth to bore diameter,
would this indicate NO free bore?

Could you possibly show a reamer photo with NO free bore?
I think, I found a possible problem......

Tia,
Don

 

[Alex Wheeler]

A zero free bore would not have the freebore bore section in the picture. You would have a taper starting right from the case neck. If you hold the edge to the light and you dont see the grind transition from the freebore to the lead, (the line on the left in the top picture) you have a zero freebore.

 

[Nvreloader]

Alex

Thank you,
this explains why I am having problems, I have a non free bore reamer,
means I have to get a throating reamer, to set the bullet depth I want.

This reamer was suppose to have a .120" free bore.

Which is better than having a free bore too long.

Tia,
Don