THIS IS GTR'S ORIGINAL DESIGN! NOT A AFTER MARKET.

This is the standard size in stock .705 Reamer Mandrel.

This multi purpose precision tool is priceless to the accuracy smith. The tooling is a must for accurizing actions and sleeving bolt bodies. It cuts the cost of having .0005 increment mandrels or stepped mandrels for multi diameter bolt bore raceways. With out a properly fitted mandrel, a canted false axis is set for the bolt bore, and a skewed machining will result!


The precision ground reamer / mandrel takes 4 weeks to manufacture. From it?s start as a blank mandrel, with rough out to hardening, onto cryo then aging to final grinding, this is state of the art tooling.

To start, the reamer is helical for interrupted cuts down the bolt bore. As with a .705 reamer / mandrel that is going to be used to rebore the raceway, it has multi position interchangeable bushings. This is to make sure you rebore down the centerline of the raceway and establish a true and concentric raceway.

As an example take a Rem. 700 action. The bolt will be receiving sleeves as part of the accurizing job. The action rear bolt bearing area has an I.D. of .7015. You install one .7015 bushing in this bearing area. Next to the front bearing area, and this I.D. is .7025. Install a .7025 bushing. Now from the front of the action, slide in the mandrel section in front of the helical section of reamer through the center of the bushings. As the reamer is advanced through the front bearing area of (put up pressure w/ your hand on the .7045 section) the action it pushes the bushings forward. As it advances it re-cuts the bolt bore to .705. Stop when you get into the ejection/load port, and then reinstall from the rear and cut again until the ejection/load port. Do not cut twice in the front bearing area of the action.

The rear portion of the reamer is a solid ground bearing area of .7045 as with the reamer section. The reamer maintains alignment on its entire cut from back to front.

This is now a install a front and rear bushings along with the .500 alignment mandrel.  This is used then to dial in the action in the ACTION BLUE PRINTING JIG. When dialed in, push the alignment mandrel back just behind the action lug abuments. This keeps the action round w/ the pressure of holding it in place. Remachine the action. Life is good

BUSHINGS SOLD SEPARATE