Chamber Checkers

Reloading Aid or “Plunk” Test in a Bag?
Reviewed by Harwood Loomis for M1911.ORG

Recently, I had a discussion with Larry Weeks at Brownells, Incorporated, about a 1911 that seemed to have problems with failures to return to battery, but only with certain types of ammunition—none of it including plain vanilla 230-grain ball ammo. The pistol fed that flawlessly, but on most hollow-point or lead semi-wadcutter ammunition it choked horribly, completely stopping the pistol and requiring some effort to clear it and get it running. After putting a micrometer to some of the cartridges that did and didn’t feed, I had begun to suspect that perhaps the chamber had been reamed undersized (or perhaps the finishing reamer step had been missed in manufacturing the barrel). Larry commented that Brownells sold a couple of different chamber checkers, and he volunteered to send me samples of them to see if one might help solve the mystery.

The issue with the pistol has not been resolved as yet, but this is a look at the tools that Brownells kindly sent us (along with one I already had on my reloading bench), and a discussion of what they do and what they don’t do.

What Larry sent us from Brownells was a multi-caliber Chamber Checker by EGW (Evolution Gun Works), and a Case Checker from Wilson Gages (not to be confused with Wilson Combat). Just to make things interesting, I also grabbed a Lyman Max Cartridge Gauge from Lyman Reloading Products. With all this hardware, I was cautiously optimistic that I’d have the tools to zero in on the cause of the problem.

The lineup included:

EGW 4-Caliber Chamber Checker

Wilson Case Gage

Lyman Max Cartridge Gauge

EGW 4-Caliber Chamber Checker

The EGW 4-Caliber Chamber Checker is a handy device for shooters who load their own ammunition and have concerns about whether or not their reloads will fit the chamber of their pistol. This is especially of concern for competition shooters, since an out-of-spec round can tie up the pistol long enough to completely ruin the shooter’s time on a stage. What this little gizmo is intended for is to be used as a quick-and-dirty “GO / NO GO” check on the ammunition. Drop each round into the appropriate hole in the nicely machined aluminum block, and if the round drops in easily, the head sits flush with the top of the block, and the cartridge then drops out easily … it should be good to go.

Unlike the other two products, the EGW 4-Caliber Chamber Checker is (as its name implies) suitable for testing ammunition in any of the four most popular centerfire calibers for semi-automatic pistols: .45 Auto, .40 S&W, .38 Super, and 9mm Luger. Each caliber has a hole that is bored and then reamed to the maximum SAAMI chamber diameter for the caliber. Inside the block, each chamber has a shoulder, located at the proper depth for the cartridge, again in accordance with SAAMI specifications. On the bottom end, each hole is bored to the SAAMI maximum bore diameter for the caliber.

The block is nicely machined from a solid block of 6061 T6 aluminum, and finished in a matte black anodized treatment. Rather than use boring bars to cut the chambers, EGW rough bores them and then brings them to final size using Clymer finish reamers—the same reamers gunsmiths use for working on barrels.

This tool is excellent for the reloader to keep next to the press, since it incorporates four popular cartridges into one handy gauge, and it’s also small enough (and light enough) for the competitor to toss into his range bag and carry along for use at matches.

In use, all that’s necessary is to drop a cartridge into the block. If it drops in cleanly and the case rim is flush with the top surface of the block, the cartridge should be within spec. As a final check, the lower portion being bored to the SAAMI diameter for the barrel bore serves as a check for bullets that are not seated deeply enough into the case. If the bullet doesn’t drop out of the Chamber Checker easily, the base of the bullet may have engaged the “bore,” suggesting that the bullet needs to be seated deeper in the case.

The EGW 4-Caliber Chamber Checker in use

What the EGW 4-Caliber Chamber Checker does not do, unfortunately, is check for cartridge overall length (COAL). Since it covers four different cartridges, each of which will have a different COAL for different types, weights and styles of bullet, it would be impossible to make one gauge that would cover even a fraction of the possibilities. So they didn’t even try. The block is machined to a uniform depth, and does not pretend to check for COAL.

The bottom of the loaded Chamber Checker, .45 Auto to the right

We really like the EGW 4-Caliber Chamber Checker. Unfortunately, it didn’t do what we needed. Since we suspected that the issue we were having was due to a tight, or undersized, chamber, a gauge reamed to the maximum allowable diameter would not replicate the suspected problem. All the ammunition with which we had problems was standard, commercial ammunition from well-known brands (some of it premium self-defense ammunition), so we knew it would work in an in-spec chamber.

On to the next candidate.

Wilson Case Gage

The Wilson gauge doesn’t bill itself as a chamber checker, but rather as a case gauge (or “gage,” as they choose to spell it). Its purpose is not checking completed cartridges, but checking empty cases before reloading. It is very nicely machined, of steel rather than aluminum, and comes in the white. However, as nicely made as it is, it serves a very limited purpose, and that unfortunately did not include anything that would help me to diagnose the problem I was dealing with.

The Wilson Case Gage is simply a heavy steel rod with a hole bored through it for a case. The gauge is cut and machined to the maximum SAAMI length for the case, and on one end there is a slot machined across both flat faces to a depth of the SAAMI minimum length. The “bore” is slightly smaller than the SAAMI maximum chamber diameter, but still larger than the SAAMI maximum for case diameter. But that’s it. There is no shoulder, and no extension to mimic the barrel bore or throat. The Wilson Case Gage is intended for checking to determine whether a case is within the allowable length for the caliber. That’s all it does … and to do that requires that the flush end be resting on a uniform, flat reference surface. If the case head isn’t higher than the outer surface or lower than the surface of the slot, the case is in-spec and suitable for reloading.

The Wilson Case Gage with a loaded round–not useful

The Wilson Case Gage is well made and does what it is intended to perfectly. Being machined from solid steel, it is virtually indestructible and should last a lifetime (or three). However, it didn’t give me any way of checking the fit of a round in a chamber reamed to minimum dimensions.

So we moved on to candidate number three.

Lyman Max Cartridge Gauge

The Lyman Max Cartridge Gauge is a single-caliber checker that does essentially what the EGW Chamber Checker does, with one added feature: In addition to checking for case length and grossly over-sized rounds, it also checks for cartridge overall length (COAL) as a function of the longest FMJ round that will fit in typical magazines and firearms chambered for the round. The upper surface, like that of the Wilson Case Gage, is machined to a flat surface with a transverse depression, allowing it to serve to indicate both maximum and minimum length for cases. The Lyman Max Cartridge gauge, however, also has a “bore” extension beyond the shoulder that establishes chamber depth. Unlike the EGW Chamber Checker, though, the overall length of each Lyman Max Cartridge Gauge is set to the SAAMI maximum COAL for the round.

For example, on the page for .45 Auto, the SAAMI specifications show a dimensioned drawing of a cartridge with a round-nose (ball) bullet. The COAL is shown as 1.190” (min) and 1.275” )max). For 9mm Parabellum, the minimum COAL is shown as 1.000” and the maximum is shown as 1.169”. The SAAMI specified case length for .45 Auto is .898” - .010”; and the SAAMI case length for 9mm is .754” - .010”.

The Lyman Max cartridge gauge and the Wilson Case Gage

The Lyman Max Cartridge Gauge for .45 Auto yielded minimum and maximum case lengths (chamber depths) of .890” and .896”, a range of .006” that leaves a margin of .002 on each end of the range. For COAL, the Lyman gauge measured 1.268” and 1.274”. Thus, a cartridge that fits within the gauge will be within maximum SAAMI specifications for COAL. For 9mm, the Lyman gauge measured an overall depth (length) of 1.162” and 1.171”. This is .002” longer than the SAAMI maximum, which could be a manufacturing error or might be attributed to the fact that my bearing surface was a stamped steel plate rather than a machined reference plate.

The Lyman Max Cartridge gauge in use

The bore diameter of the Lyman Max Cartridge Gauge for .45 Auto was .455. The SAAMI specification for bore and grooves is .442” + .004” and .450” + .004”, respectively. Thus, the “bore” end of the Lyman gauge is .001” larger than the SAAMI maximum groove diameter for a .45 Auto barrel. The chamber itself measured .477” in diameter. The SAAMI minimum and maximum dimensions are .476” - .006”, so the Lyman gauge is again .001” larger than the maximum SAAMI dimension.

Finally, the “bore” end of the Lyman Max Cartridge gauge is sized to the maximum diameter for the grooves of the respective caliber. This is unlike the EGW Chamber Checker, with has the “bores” reamed to the bore diameter rather than to the groove diameter.

The Bottom Line

My problem was that I suspected either a tight chamber or a tight “leade” section in the barrel. The only way to test for this would be to subject the rounds that had problems to some sort of chamber or cartridge checker that is machined to minimum dimensions rather than maximum. Unfortunately, all three of these products are well-made and generally well-suited to their intended purpose … but none of them includes as its intended purpose diagnosing the problems my pistol patient was experiencing.

The Tale of the Tape

The table below provides comparative dimensions for the three candidates:

Summing it all up

Although all three of these tools are quality products and will do what they are intended to do, what we needed was a hand-held tool or gauge that would allow us to replicate the aptly-named “plunk” test that is often used by 1911 shooters to help diagnose if a problem is in the pistol or if it might be caused by the ammo. The fact that none of these tools does that is not a criticism; the simple fact is … that’s not what they were intended to do, so we should not be surprised that they don’t do it.

In this reviewer’s opinion, for use on the reloading bench I think I prefer the solid steel construction of the Lyman Max Cartridge Gauge, along with the fact that it checks for COAL as well as case length and diameter. But hauling a set of the Lyman gauges around to events and ranges adds weight and pieces to be kept track of. For something to carry around in the range bag for making checks in the field, the EGW Chamber Checker is perfect. The Wilson Case Gage is also a good tool, but in this reviewer’s opinion it offers less flexibility than either of the other two.


M1911.ORG is grateful to Brownells, Incorporated, and to Larry Weeks for the opportunity to evaluate the EGW and Wilson tools.

You may discuss this article here.


200 S. Front Street
Montezuma, IA 50171
Tel: 800-741-0015
Web Site: