Building a Custom 308 Precision Chassis Rifle- PART 3- Cutting the chamber, final assembly and test fire

This is the third and final post of my series on building a custom 308 precision rifle. The first two parts can be found here:

Building a Custom 308 Precision Chassis Rifle- PART 1, Barrel removal, action blueprinting
Building a Custom 308 Precision Chassis Rifle – PART 2- Barrel preparation and threading

Before we get to the work, please take a look at the following disclaimer:

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Any modifications made to a firearm should be made by a licensed gunsmith. Failure to do so may void warranties and result in an unsafe firearm and may cause injury or death.

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I ordered the following tools and parts from Brownells to complete this project:

In addition to these parts, for this build I selected a MDT ESS chassis system. The MDT ESS chassis system offers a series of advantages over a fiberglass stock. It is readily adjustable to fit a wider range of shooters and optics and in this configuration it comes with a continuous top rail for use of additional equipment; and most importantly, the ESS chassis is easy to install.

Since we are going to do a lot of barrel work, we need to use a lathe- not really a way around it when you are building off of a rifle blank. This is my lathe (when it was new, it is way filthier now). It is a Precision Matthews PM-1440GT. I’ve found it does everything I could ask of it exceptionally well.

The breech face of the barrel on Remington 700 rifles and clones requires a bolt nose recess. This can either be cut with a boring bar or a form tool. I use both methods at the shop. In this case, I am using a form tool/counter bore held in a floating reamer holder.

I use a depth micrometer to check the depth of the cut. Depending on your rifle, this is typically around .150″ deep.

With the bolt nose cut, it is time to ream the chamber. In this case, I’m holding the reamer in a floating reamer holder and taking it slow. I use a slow spindle speed, start the lathe, feed the quill slowly, stop the lathe, retract and clean the reamer and repeat the process. When I get close to full depth I begin to check the headspace.

These are the headspace gauges. I’m using a go and no-go gauge. First I place the go gauge in the chamber and screw the action into place.

When the action and recoil lug and threaded onto the barrel and the go gauge is in place, there is a small space in front of the action (top photo). This is the depth the chamber needs to be cut. To measure this, I use a set of feeler gauges. Once I have the remaining depth of cut determined, I cut half this depth and repeat the process.

When the headspace is correct, the handle will easily close on the go gauge and stay open on the no-go gauge.

The edge of the counterbore needs a chamfer (or radius) to help feed rounds and prevent the brass from being scratched. I like to cut this with a boring part.

The finished chamber looks great!

The muzzle end of this rifle will be threaded 5/8″-24 for a brake. I dial in the the barrel on the lathe in the similar manner as I did to chamber it. Once the bore is concentric to the lathe, I cut the shoulder for the threaded tenon.

I then use a high-speed steel threading tool to cut the threads.

I like the way helical flutes look on a bolt action rifle. I cut these on my CNC Mill using a 3/8″ 4-flute ball- nosed carbide end mill.

After the barrel is torqued into the action, it is time to install the chassis. This is by far the easiest part. The MDT ESS simply bolts into place. Unlike a traditional stock, fitting and installation isn’t needed.