Steel-Cased 7.62x39 mm In Ruger Mini Thirtys?

by
posted on June 25, 2014
mini30F.jpg

Q: I’ve been shooting Russian-made 7.62x39 mm ammunition in my Ruger Mini Thirty. The steel cases are coated in some sort of lacquer for corrosion protection, which I think has been causing rounds to get stuck in the chamber. My brother has had similar issues, and he said the lacquer is causing a residue that is very difficult to remove-even after a thorough cleaning. Anyhow, I believe that this cheap ammunition is a failed product that is being offered and that NRA members should be made aware of the issues.

A: Thank you very much for your question concerning functioning issues of steel-cased ammunition in your Ruger Mini Thirty rifle. This is a sensitive, and sometimes emotional, subject for a number of 7.62x39 mm shooters. Needless to say, proper, efficient, and accurate functioning of firearms, especially autoloaders, requires that the firearm and ammunition “mesh.” In other words, the maker of the firearm and the maker of the ammunition must know and appreciate the dimensional and performance standards of the other party. It would do neither of them any good to design and develop their products in total isolation. That would represent not only bad business practice, but also lack of concern for consumer satisfaction, not to mention consumer safety.

That is but one reason for the existence of Sporting Arms and Ammunition Manufacturers Institute (SAAMI). Membership in SAAMI is voluntary, but essentially involves the agreement to produce products that will safely fit and function with other members’ products. The key word is “tolerance.” The tolerances allowed are close, but permit the manufacturers a degree of choice in design.

The 7.62x39 mm is an active SAAMI cartridge. One of the several cartridge “features” defined by SAAMI concerns chamber pressure produced. The means by which this property is measured requires a brass case, which immediately precludes steel-cased ammunition.

To get Ruger’s perspective, I contacted a member of the company’s service department. He was quite familiar with your concern, and also mentioned issues of extractor breakage and debris from the case coating fouling the firing pin and gas system, and that the ammunition is not to SAAMI specification. Ruger’s official comment regarding ammunition is, “Only factory ammunition manufactured to U.S. Industry Standards should be used in a Ruger firearm.”

That begs the question of why the same ammunition usually works fine in SKS and AK firearms? (Note that neither guns nor ammunition are produced to SAAMI specs.) The answer goes back to tolerance and design features of the firearm makers. Those rifles and their chambering were designed for infantry use. In such cases, accuracy is important, but reliability is paramount. The Ruger will deliver significantly better accuracy and can be utterly reliable, but it will require that the ammunition used be constructed with the same attention to specifications as the firearm.

-John W. Treakle

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