Pilot Diameter Chart
Copyright 2019, Fred Zeglin, reprinted by permission of the author.



These Charts come from Fred’s book, “Gunsmith Tools, Cutters, & Gauges – A Primer“.
There is so much more in the book, check it out!

Copyright 2019, Fred Zeglin, reprinted by permission of the author.



These Charts come from Fred’s book, “Gunsmith Tools, Cutters, & Gauges – A Primer“.
There is so much more in the book, check it out!

Before accepting a barrel for machining to accept screw-in chokes, you must measure the outside diameter (O.D.) to determine if there will be sufficient wall thickness after machining. “Mike” the O.D. of the barrel and the O.D. of the tap for the particular gauge. Subtract the O.D. of the tap from that of the barrel,…
By Brady Kirkpatirick Introduction If you’re in the world of firearms, you’ve likely heard the term ‘headspace.’ But what is it, and why is it so vital? My name is Brady Kirkpatrick, the founder of GunMade.com, and I’ve spent years delving into the intricacies of firearms, including the concept of headspace. In the simplest terms,…
There is a lot to learn about chamber prints. We recommend the post on this blog. We are asked for reamer prints on a daily basis. We have never provided them as they do not represent a specific tool. Prints are representative of what you would receive. Reamer makers like all machinists use tolerances when…
We often have clients ask about roughing reamers. We have never carried them because that would more than double our inventory costs and would not come close to paying for the expense. In 2025 Forster started offering a new batch of tools, “Piloted Roughing Drills”. They are offered in three (3) pilot size ranges. The…
We at 4D Reamer Rentals LTD have long had requests for some kind of protection policy against the cost of broken, damaged or lost tools. Our clients are responsible people who understand that under the Rental Agreement they have reasonable obligations. This protection plan is one way to handle that obligation. There are a lot…
Designed by John Lazzeroni and introduced in 1996. This 7mm cartridge was dropped from the Lazzeroni line in 1999 when the 7.21 Firebird came out. It could push a 120 grain Barnes X at 3697 feet per second. As well as a 140 grain at over 3500 fps. We picked up the reamer for this…
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