Lands and grooves for .338 Win mag.

[gene so]

We are building a rifle for informal target shooting and long range hunting. Barrel is Pence made, 33. Inches long and straight 1 1/2" in diameter. It will be bedding blocked into the lengthened prone stock.

The reamer was ordered for a tight neck, no turn chamber. Reamer arrived and the pilot is .330 and the grooves measure.328
Putting a .327 pilot bearing on the reamer would allow us to chamber this long, heavy barrel. But we are faced witha legitimate challenge. How high will the pressures increase with the .002 narrower dimensions when the rifle is fired? This is one of two barrels made for a Colorado rancher, probably some time ago.
I am hoping someone with adequate gunsmithing and practical experience has faced this challenge previously. Thank you in advance.

WW

 

[Kurz]

I am hoping someone with adequate gunsmithing and practical experience has faced this challenge previously. Thank you in advance.

First of all, this will depend on how you performed the actual measuring of the lands and grooves, grooves especially. We use very specialized tools to measure groove depth for each groove in the barrel. Lands are fairly simple with the proper tools. The top of the lands should measure .330" and the bottom of the grooves should measure .338", although you might find very, very slight variations of 0.0001" per groove.

If the measurements you have provided are accurate, that barrel should be sent back to the manufacturer. It's not a standard .338 barrel. Trying to create a new methodology in order to get what you need or want is a waste in my opinion. Get the barrel you're supposed to have and get on with the project.

Good Luck!