Martindale Gauge

Martindale Gauge

If you reload 45 ACP for automatics (but not necessarily for revolvers), you need one of these gauges from Bruce Martindale ( It’s basically a bored-out nut — made on a precision lathe — and you pass all your brass through it before reloading.

If the brass passes, reload it. If it won’t, chuck it.

Fired brass is subject to some interesting ills.

First, every time a gun such as the model 1911 is fired, the slide is propelled backward, pushed by the rim (bottom) of the shell. Over time, this causes the solid brass rim to “squish out” and increase in diameter. Eventually, the rim will be too large to fit under the extractor and the gun will jam with a partially fed round. Similarly, the extractor “hook” may nick and slightly draw-out the area it contacts.

Most so-called “full length” resizing cannot correct this problem. “Roll resizers” may do better but such machines are usually the domain of commercial reloaders who can afford the larger investment required.

Next, in some guns such as the Glock in 45 ACP, it is thought by some that the slide’s rearward movement begins while a substantial pressure still exists in the shell and, coupled with the different chamber end found in that gun, the brass in that area is given a bulge that stresses the brass beyond its ability to recover.

“… the unsupported region of the chamber [is] a fact of life in any automatic but much worse in some types of guns.” Bruce Martindale, personal email, November 24, 2008.

Although full-length resizing may temporarily compress such brass back into tolerance, the shell has been overstressed and will not “spring back” correctly after firing ever again. Worse, if during reloading the brass expands in the later stages after resizing, it will be left “fat” and may be too large to fit into the gun’s chamber. A jam will result. This type of failure can also arise from overuse, overloads, weak brass or a bulged or oversized chamber.

Bruce adds a warning about re-using such brass.

“… it is possible for bulged brass to fail (burst) if reused in a gun with inadequate chamber support. True it is a bit ‘broad in the beam’ but it may still chamber, with no indication of the upcoming failure or if it doesn’t fully chamber, it can burst if the gun is capable of firing out of battery.” (Same email.)

Bottom line: Bulged brass and hammered out rims are bad, even dangerous.

When I first started reloading 45 ACP, I became a “range scavenger”. If anyone near me was shooting that size and they weren’t picking up their brass, I’d ask if I could have it. The answer was almost always, “Yes,” and brother, did I think I was getting a deal.

Fast forward a couple of months and you’d see me dealing with jams and misfeeds about once every 20 rounds or so.

Fast forward again and you would see me in the garage running all my brass, shell by shell, through the newly acquired “Martindale Gauge” — and discarding almost 30%. (Glocks were, and probably still are, very popular at the range I was using at that time.)

And then fast forward and look, and forward to look again, and fast forward again and again and you won’t see a single jam in my admittedly tight-chambered wadder.

Bruce’s directions will give you the details but the process goes basically like this:

  1. Clean the fired brass as usual, then
  2. Mouth first, drop each piece of brass through the Martindale Gauge and, if it won’t go through easily, reject it.

Bruce makes his gauges for a nominal fee on an irregular basis. You’ll need to email him to get “on the list”. He can be reached at

And tell him I said, “Thanks!”

2 thoughts on “Martindale Gauge

  1. Pingback: Case gauge vs. Chamber

  2. Pingback: 1911 jamming badly with SWC rounds - Page 2

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