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Making a Cartridge Check Gauge
by Roy Seifert


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Disclaimer:  This article is for entertainment only and is not to be used in lieu of a qualified gunsmith.  Please defer all firearms work to a qualified gunsmith.  Any loads mentioned in this article are my loads for my guns and have been carefully worked up using established guidelines and special tools.  The author assumes no responsibility or liability for use of these loads, or use or misuse of this article.  Please note that I am not a professional gunsmith, just a shooting enthusiast and hobbyist, as well as a tinkerer.  This article explains work that I performed to my guns without the assistance of a qualified gunsmith.  Some procedures described in this article require special tools and cannot/should not be performed without them.

Warning:  Disassembling and tinkering with your firearm may void the warranty.  I claim no responsibility for use or misuse of this article.  Again, this article is for entertainment purposes only!

Tools and firearms are the trademark/service mark or registered trademark of their respective manufacturers.

Introduction
If you shoot a lot like I do then you are probably also a reloader.  If you only shoot factory ammo then you either donít shoot very often, or youíre in a higher income bracket than I am.  Shooting factory ammo has some advantages over reloading; it is very reliable and very consistent.  You almost never have a failure to feed, failure to fire, a squib or over-charged round with factory ammo.  A squib is a round that has little or no powder in it.  When factory ammo is fired through a chronograph the velocity often has a very low standard deviation.  Standard deviation is a statistical value that shows how much variation or "dispersion" exists from the average.  The smaller the standard deviation value the more consistent the load, which results in better accuracy.  A standard deviation value of 10 or less is considered excellent for ammunition, and factory ammo often reads way below this value.  But for me I just canít afford to throw 2, 3, 4 or more quarters downrange every time I pull a trigger.

Reloading is not only cheaper than purchasing factory ammo, but there is a certain zen to the repetitive processes involved.  With reloads you can tailor your loads to your particular gun and need, whereas with factory ammo what you buy is what you get.  However, reloaded ammo can have many problems including those mentioned above. 

Raised Ring of Lead
Most semi-auto pistol cartridges use rimless cartridges which headspace on the mouth of the case.  Although it looks like the case has a rim, this is actually the extractor groove.  When I first started reloading semi-auto pistol rounds with lead bullets I quickly discovered a problem.  Most pistol caliber seating dies have a built-in taper to apply a taper crimp to the case mouth.  At the time the crimp was applied the lead bullet was still being pushed into the case which caused a ring of lead to be pushed ahead of the case mouth.  This problem did not occur with jacketed bullets, and was a non-issue with revolver cartridges.  Chamfering the inside of the case mouth reduced this somewhat, but it didnít eliminate it.  The cartridge would headspace on that ring of lead instead of the case mouth, which prevented the slide from going completely into battery. 

This was a constant problem for my lead pistol reloads until I discovered the Lee Precision factory crimp dies.  Although this requires a separate step, the case is crimped after the bullet is completely seated so there is no ring of lead causing the cartridge to headspace incorrectly.

Cartridge Check Gauge
The final quality control step I perform to my hand-loaded ammunition is to see if it will fit in the chamber of the gun in which I plan to shoot it.  This will find any bulged or out or spec cases, or in the case of lead reloads for pistol calibers, improper headspace caused by a raised ring of lead.  I do this by using a cartridge check gauge.

Whether you know it or not, every gun comes with a built-in cartridge check gauge; itís called the chamber!  Revolvers come with 5 or 6 chambers in the cylinder, and pistols and rifles come with one in the barrel. 

 

To use a revolver cylinder to check loaded ammo I first measure each chamber to find which one is the tightest.  If my reloads will drop into the narrowest chamber with no friction, then they will fit in all the other chambers.  If Iím using a single-action revolver cylinder, I remove the cylinder from the frame.  If Iím using a double-action revolver Iím very careful; safety first, last, and always.  I drop the loaded round into the tightest chamber and if it fits, I remove it immediately and put it in my ammo box.  I DO NOT SWING THE CLINDER CLOSED WITH THE LOADED ROUND IN THE CYLINDER.  If I was to close the cylinder I have now loaded the revolver, which should never be done unless ready to fire.  If the cartridge does not seat completely in the tightest chamber, I set it aside to rebuild it later.

 

For a semi-automatic pistol I use the barrel as the chamber check gauge.  Most modern pistols allow you to remove the barrel.  I shoot a lot of .45 ACP so I use one of my 1911 barrels.  The process is the same; drop a loaded round into the chamber; if it drops in without any friction, and sits flush or below the barrel hood then it passes.  If I am checking cartridges in a pistol with a fixed barrel like a Walther, I remove the slide and drop the cartridges into the chamber.  Again, if the cartridge fits with no friction and flush or below the barrel hood the round passes.

 

EGW makes a four-caliber cartridge check gauge available from MidwayUSA product #744135.  Drop the reloaded cartridge into the appropriate hole, if it drops in with no friction and fits flush with the top of the gauge itís good to go.  They make one for revolver calibers as well.

 

L. E. Wilson also makes a cartridge check gauge for many individual calibers also available from MidwayUSA.  Type in ďcartridge check gaugeĒ in their search field and you will see all of the choices available.

Making a Cartridge Check Gauge
One of the potential problems I see with these stand alone gauges is that the hole is not the same size as the chamber of the gun in which the ammo is to be used.  I decided to make my own chamber check gauge for .45 ACP that would match all of my .45 ACP chambers.

 

How would I know the gauge would match all of my .45 ACP chambers?  Long ago I purchased a .45 ACP chamber finish reamer from Brownells #513-051-451.  I used this reamer in all of my .45 ACP barrels and cylinders to ensure all of the chambers were of the same dimension.  Back in 2011 I purchased a Rock Island Armory M1911A1 as a gift for my son, but the slide would not go into battery with most of my reloads, and even some factory ammo.  It turned out the chamber was way undersized so I used this reamer to finish the chamber and bring it to the proper dimensions (refer to my article Reaming a .45 ACP Chamber).  Using this same reamer to make my gauge will ensure the rounds will fit in all my .45 ACP guns.

 

I purchased a one-inch diameter brass rod 6-inches long from OnlineMetals.com.  I took a hacksaw and cut off a piece 1 3/8Ē long.  I cut it just a little longer than it needed to be because I canít make a straight cut freehand.  I mounted it in a machinist vise mounted to my table-top milling machine and used a 1/2Ē square end milling bit to square off the cut edge.  The square piece of metal you see below the brass rod in the above photo is a parallel.  It is cut perfectly square to ensure the piece Iím milling is straight and square.

 

I marked the center of the piece then milled a 0.4515Ē hole through the center using a 0.250Ē square end milling bit.  The front of the chamber reamer measured 0.451Ē so I wanted the hole to be just a bit larger so the reamer would turn, but not wobble.

 

I set the brass piece upright in a padded vise and used a large tap handle to begin cutting the chamber.  I made sure everything was lubricated before cutting.  Brass is much softer than steel so I had to be careful I didnít cut too deeply.  The reamer was designed for a 1911 barrel; the lip in the center of the reamer indicated by the arrow in the above photo is meant to touch the barrel hood indicating the chamber was cut to the proper depth. 

 

I marked the reamer at the approximate position where I wanted to stop reaming.  When I got close to that mark I used a .45 ACP go headspace gauge to monitor my progress.  When the headspace gauge fit flush with the top surface of the brass I was finished.

 

Now I can take a couple boxes of reloaded ammo and an empty cartridge box, sit in front of the TV, and check my reloads.  If the cartridge seats smoothly in the gauge, and sits flush with the top, and it doesnít have a high primer which I check by running my finger over it, I put it in the completed box.  If the cartridge doesnít seat smoothly and fully into the gauge, or has a high primer, I set that round aside to rework it.

Summary
Ok, so purchasing the reamer, the brass, and other tooling is way more expensive than the $20 for the EGW or L.E. Wilson gauges.  But since my gauge matches all of my .45 ACP chambers, I know if a cartridge fits in my gauge, it will also fit in all of my .45 ACP revolvers and pistols.  So why not just spend the $20 for the EGW gauge and ream it with my reamer?  The 6-inch brass rod cost more than that.  I plan to use that brass rod for other projects so it was actually cheaper to fabricate my own.  The reamer has more than paid for itself since I saved the labor of having a gunsmith fix my sonís 1911 chamber and ream my other chambers.  So all in all I believe Iím ahead of the game.

 

 
   © Copyright 2014 Roy Seifert.