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Old March 9, 2013, 08:36 PM   #9
Rainbow Demon
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Join Date: September 27, 2012
Posts: 397
I was also speaking of the Chilean 1895 and Spanish 93 and 95 actions.
While these are plenty safe enough with M80 Ball if rebarreled properly and in good condition, some Chilean rifles were instead rebored and a chamber insert soldered into a reamed out chamber shoulder to take up the slack between the 7mm 57mm chamber and the 51mm chamber of the 7.62 NATO.

While some of the Spanish rifles have digested regular M80 Ball and the more common .308 hunting loads with no problems, others exhibit lug recess set back, and there have been a few blow ups, though defective ammo is the most likely cause.

Most 98 actions have a much greater safety margin. Some of these have had problems with set back when extra heavy loads are used.
While machining is pretty good on any license built Mauser (with the exception of a small run of FN Mausers that suffered cracked lugs due to insifficient radius cuts),Metalurgy and thickness of the carburized layer runs the gamit.

The problem isn't so much with the rifles, but rather the poor quality of a lot of NATO surplus ammo.

19th century German proof testing took degradation of propellents into consideration. The Special powder used for proof testing was formulated to give the aprox pressure of a propellent damaged by poor storage in tropical climes.
Powder charge weight was the same as the regular powder but pressure about 20-25% higher.
The Gew 88, the Model 91, and Model 93 were proofed at 58,000 CUP.
The 98 rifles were proofed at higher presures, IIRC around 75-78K CUP.

The 1895 Winchester operated fine with WW1 era .30-06 ammo at 48,000 CUP but often suffered lug set back with M1 Ball at 50,000+ CUP.

PS
The greater the operating pressure of a particular load the greater the pressure increase one may expect from any degradation of the propellent.

Last edited by Rainbow Demon; March 9, 2013 at 08:45 PM.
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