Thread: Rebore.

Originally Posted by Nakihunter

My understanding is that any existing caliber needs to be bored out first. This brings it back to a blank stock and then a button can be drawn through this. So a 243 barrel will need to be bored out to a new hole of say 249 & then rebore to a minimum 257. The grooves are usually 0.004 inch for a total caliber of 0.008 more than the original bore diameter. (For example 308 has a 300 bore & 7mm = 284 with a 276 bore.)

The late Din Collings once told me that a well used barrel would have a better molecular structure for reboring.

Nice idea
But wrong

Yes the steel is stress relieved by thousands of shots
And yes you can put a button through and correctly sized piece of steel
But you can NOT put it through and existing profiled barrel and get a usable barrel

Buttons are not pulled through a bore diameter drilled barrel blank
They are made especially for being pulled through a certain fixed diameter of steel
The drilled and reamed hole they go through is slightly smaller than final bore diameter
This allows the button which is actually larger that the final bore and groove to be pulled through and the known diameter and known type of steel too spring back to final bore and groove