Truing a Remington 700 Action on a Lathe
“Blueprinting” or truing an action is the process used to square the critical surfaces of a bolt action rifle receiver prior to barreling. This is done to enhance accuracy.
In a previous post I covered a method that did not require a lathe, using a specialized kit from Manson. Alternatively, a metal lathe can be used to perform the same task.
To view these posts, see:
Those critical of the Manson style truing kits argue that taps and dies, no matter how stout, follow existing holes and do not provide the same results as single-point cutting the receiver on a lathe.
Here, I will be working on a new Remington model 700 short action with a .223 bolt face. I will be truing the following surfaces:
- receiver ring
- receiver lugs
- minor diameter of the the receiver threads
- receiver threads
- front and rear faces of the bolt lugs
- bolt nose
- bolt face
This post will cover #1-4 in the list above. To see how the bolt is trued, read Truing The Bolt On A Remington 700
Note: in addition to these steps, some gunsmiths will also ream the bolt hole to a larger diameter, sleeve the bolt, bush and recenter the firing pin hole.
I ordered the following items from Brownells:
- Remington 700 short action
- receiver mandrel set .701″ and .703″ (521-103-000)
- Viper’s bench rest chambering and truing fixture (100-013-366)
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All lathe work is conducted on a Grizzly gunsmith’s lathe.
The chambering & truing fixture that I am using has a series of brass tipped screws, located at 12, 3, 6 and 9 o’clock around the receiver. Dial indicators and the mandrel are used to dial in the receiver, as shown in the photos below.
I make the receiver lug cuts from the receiver wall in. I have the DRO zeroed to the inside end of the receiver wall and take a series of light passes.
Its critical you don’t allow the boring bar to move too deeply into the receiver. My lathe has a DRO, before making any cuts, I set the maximum depth to “0.0000” and take caution to avoid cutting too deeply or crashing into a receiver lug.
Picking up the threads can be a little intimidating if you haven’t tried it before, however, it is not that difficult. This is the process I used:
- Set up the lathe for threading operations. In this case the threading tool is adjusted with a fish tail to cut square to the receiver, the lathe is set to cut 16 threads per inch (for the M700) and the lead screw is engaged.
- Set lathe to 70 RPM- that’s the slowest my lathe will go.
- Adjust threading tool so it will not make contact with the receiver.
- Turn on lathe, engage the half nut at the appropriate point on the threading dial (on my lathe this is an marked graduation for even thread pitches) and allow the threading tool to move two or three threads into the receiver then turn off the lathe.
- The compound, mine is set at 29.5 degrees, is then used in conjunction with the cross slide to adjust the tip of the threading tool into the root (or valley) of the thread. The thread is now located.
I used the cross slide on the lathe to adjust the depth of cut, .001″ at a time. A gauge I had previously made (.013″ over std diameter) was periodically checked against receiver to determine with the proper depth of cut was achieved.
Once again, it is critical you don’t bump the threading tool into the receiver lugs or cut too deeply into the receiver. I zeroed my DRO to prevent this, however, a dial indicator could be used as well.
Once the threads are cut to depth, the bolt surfaces need to be trued. To see how the bolt is trued, Truing The Bolt On A Remington 700. Finally, the action will be ready for a new barrel.
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