August 14th 2021
This clever DIY tool was discovered by Frank Shuster, a Forum member who unfortunately passed away in 2015. Frank was a skilled shooter and was always willing to help others. Here’s one of Frank’s clever inventions. He invented a method to measure the length a rifle’s chamber with a fired cartridge box. Frank’s method involves cutting a “collar” from a portion of the case neck. This is then used to slip over a bullet that has been loaded with powder or primer. The collar will move back as you chamber the dummy cartridge. To ensure that the dummy rounds can chamber fully, make sure the bullet is well seated.
You can make the gauge shown here at home with parts you already have. Frank explained that he used a Dremel to remove the neck portion of the front case neck. To de-burr both edges, use a jewelers needle file. You don’t need to cut a perfect square surface, as you will be using the original straight mouth to contact the chamber’s front. Any bullet can be seated to the normal length. Next, apply a small amount of oil to the bullet’s ogive. Then slide the ‘collar” over the bullet. Next, chamber the dummy cartridge and close the bolt. Take the round out slowly and carefully, and measure it with a caliper (see top photo).
Frank’s DIY chamber length gauge is very useful. Frank wrote in a Shooters Forum thread: “I have compared length dimensions doing this way and with my chambering reamer drawing and the Sinclair gauge and they all fall within.001?” or so.”
Custom Chambers May Not Use Commercial Chamber Length Gauges
Frank used Sinclair chamber-length gauges in some applications. These bullet-shaped gauges fit into a cartridge but Frank found it inconvenient to order the gauge without paying $6 shipping for a $7 item. Sinclair gauges might not fit into a custom chamber that has a smaller neck dimension due to the excessive diameter of the ring at its end.
The collar-type, homemade gauge can be used in place of commercial gauges. The homemade gauge will work with smaller-than-standard chamber neck dimensions, as long as you use a piece of appropriately-turned fired brass that fits your chamber.
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Tags: Chamber Length Gauge, DIY Chamber Gauge, Frank Shuster, OAL Gauge
