6mm & 22Caliber Leade or Freebore

[anyrange]

I am just wondering what sort of leades or freebore the bench rest guys are using in their 6mm and 22 caliber bench guns.

My Wilson 6XC barrel I am using first on my Tubb Gun came with the best that I can tell a leade in the .100" to .120" range. After 138 shots the it has grown .036" thousands and now the 107 Sierra MK are in the case .175". The 6XC neck is .305" long which leaves me .130" behind the bullet. It Looks to me that one could start with zero leade and after a few shots the bullet's rear shoulder would be right at the case neck base.

 

[Cheechako]

I am just wondering what sort of leades or freebore the bench rest guys are using in their 6mm and 22 caliber bench guns.

My Wilson 6XC barrel I am using first on my Tubb Gun came with the best that I can tell a leade in the .100" to .120" range. After 138 shots the it has grown .036" thousands and now the 107 Sierra MK are in the case .175". The 6XC neck is .305" long which leaves me .130" behind the bullet. It Looks to me that one could start with zero leade and after a few shots the bullet's rear shoulder would be right at the case neck base.

Larry

I think you're mixing leade/freebore with the throat. Freebore is that part of the chamber immediately in front of the case neck that is reamed cylindrical, free of rifleing. The throat is the tapered transition to full rifleing.

If you have measured a growth of .036" in the first 138 shots there is something wrong. I'd guess it's your measuring methods but it's just a guess. The throat should not wear at anywhere near that rate. Did you measure and record the jam length before shooting the rifle? Did you measure it again after 138 shots using the exact same tools and methods?

Ray

 

[anyrange]

Ray,
I used the same bullet and case for measuring using a RCBS Precision Mic. I may have determine the initial length with the barrel off and jamming the case to stop on its shoulder while seating the bullet. In both before and after firing the bullet was seated to jam point in the chamber. When I put OEM barrel on and fire lap it, I plan on measuring after each shot and clean.