The fitting of the Clark ramped barrels requires that two cuts be made to the frame. The first is a cut through the feed ramp of to a depth of .315" from the top of the frame. The second is a cut .270" from the top of the previous cut, extending back to leave a thickness of .210" from the rear of the cut to the front of the magazine well. This fitting gauge will assist you in making those cuts accurately with a minimum of extra measuring.
1. Description of the gauge.
The gauge is a "T" shaped piece of steel with a 1/16" pin extending from one arm of the gauge. The length of the bottom arm of the "T" is .315". The distance between the top of the pin and the top of the gauge is about .225". These two reference points are used to fit the custom barrel.
2. Use of the gauge.
I use an angle plate clamped to the mill table and indicated in for this installation. The frame is then clamped to the angle plate and indicated in along the top rail to assure that it is perfectly square with the mill head. Clark recommends that a non-standard mill cutter of .365" be used but states that a standard .375" (3/8") cutter is acceptable. I use a standard 3/8" carbide cutter. This is especially necessary with some of the stainless steel frames which have a harder heat treatment than most carbon steel frames.
Measure the width of the frame and center the spindle over the work piece. Install the 3/8" endmill and mill to a depth of .125". Then back off the endmill and insert the bottom arm of the "T" into the cut. Measure the distance between the top of the frame and the bottom arm of the "T". This is the remaining distance to be milled. Use the gauge several times during the cutting process to insure that you do not cut too deeply. A set of calipers may be used for the first measurements and feelers gauges for the final measurements. Cut until the bottom of the "T" cross arms rest on the top of the frame.
Move the endmill forward, into the dust shield area. Then, lower the cutter .270". Cut rearward, using the arm with the pin as a gauge. When pin is firmly against the rear of the cut and the top of the "T" just touches the forward edge of the magazine well, you should be within a few thousandths of correct fit. From here, use the barrel to be installed as a final fitting gauge and mill the frame until the barrel ramp is flush with the front of the magazine well.
USE OF THIS TOOL BY INEXPERIENCED OR UNTRAINED INDIVIDUALS MAY RESULT IN AN UNSAFE OR UNUSABLE FIREARM. NEITHER THE MANUFACTURER, NOR THE RETAILER, ACCEPT RESPONSIBILITY FOR ANY IMPROPER USE. THE DETERMINATION OF FITNESS IS THE SOLE RESPONSIBILITY OF THE USER.
Copyright © 1999 by L. Bengtson Arms Co.