The common question seems to be, “Is it safe to shoot 7.62 NATO or .308 Winchester from an 1893 type rifle which has been rebarreled and” 7.62” stamped on the receiver ring? What about this mystery cartridge the 7.62 CETME?”
Let’s get this CETME cartridge debunked right now. The ORIGINAL cartridge (among a number of “prototypes”) was a 7.92 x 40mm round developed for the (then) experimental CETME rifle. It was then changed to a 7.62 x 51mm cartridge but at a lower pressure and lighter bullet then the 7.62 NATO. According to sources, this 7.62 CETME round was only used in two rifles, the CETME model A and B assault rifles. The 7.62 NATO is 7.62 x 51mm round also, but is loaded at a higher pressure and is still in use. The various re-worked rifles, including the FR7/8 and Guardia Civil, were ALL re-chambered in 7.62 NATO.
Recall we said earlier that Mauser upgraded his action designs, materials and heat treatment techniques to keep up with powder and cartridge developments? This may well be the most important thing we discuss about the 1893 action. The original cartridge for the 1893 is the 7 mm Mauser or 7 x 57. This cartridge was designed to have a breech pressure of no more then 46,000 cup. The 1893 action is designed within these parameters. Now, all actions are “proofed” with a high-pressure cartridge, often called a “Blue Pill”. However, they are not fed a steady diet of them. All Mauser actions have a bit of insurance built into them, they have to, however, they are not meant to push the envelope all the time.
The American ammo companies stay within that 46,000 cup ceiling for a good reason. I have many reloading manuals. The Speer Manual, specifically states the 1893 type actions should be limited to starting loads in 7 mm Mauser. Other loading manuals have 7mm Mauser loads in two sections; mild loads for military rifles, another section for commercials (Rugers, Winchesters etc).
In the 1950’s Spain rebarreled many 1893 types to the 7.62 NATO cartridge. Cartridges of the World, 5th Edition by Frank C. Barnes, DBI books, 1985, state the 7.62 NATO, M80 Ball, the standard rifle cartridge, has an average max pressure of 50,000 psi.
However, what about the .308 Winchester? In the book: Handloading, William C. Davis, NRA Publications, 1981, it states: “The commercial .308 Winchester is normally limited to a working pressure of about 52,000 cup, and the maximum average for commercial ammunition should not exceed 55,200 cup.”
Military rifles tend to have roomy chambers, usually crowding the high side of tolerance. Throats also tend to be on the long side. Both these factors translate into slightly reduced pressures. So, it seems that firing the 7.62 NATO round in an 1893 type that has been rebarreled and marked 7.62 NATO is safe. Let’s remember though, these are old rifles, some in excess of 100 years old. It would be wise to have the rifle completely inspected before firing. And, even then, a rifle, which appears perfect, will benefit greatly from reduced pressure hand loads.
No less of an authority then Frank de Haas, in his book Bolt Action Rifles 4th Expanded Edition, Krause Publications, 2003, states this about 1893 type actions: “I advise limiting the cartridge choice to those originally used, or to other cartridges within the following limits: any cartridge developing less then 45,000 psi breech pressure…I consider all of these actions…as having marginal strength and safety for the .308 Winchester (7.62 NATO) cartridge.”
Notice de Hass states “marginal”, not dangerous. Again, this seems an admonition to proceed with caution, not a condemnation of the 1893 type.
