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Keep them Shooting: Making .30-06 into 7.65 Argentine Brass

Sporterized 1891 mauser

Sporterized 1891 mauser

Whether you call them Argentine, Turkish or Belgian, the 7.65X53 cartridge is a pleasure to shoot in the Model 1889-91 Mausers.  Thousands of these fine rifles made it into the United States after World War II and sold at extremely reasonable prices.   Some were sporterized for hunting and others were left in their military dress.  The only real problem with them is that brass is difficult to find and expensive.  Norma brass will set the buyer back about $1.60 a piece before the cost of shipping. That makes shooting the beautifully crafted Mauser taking up space in the back of your gun safe a bit pricey.  Luckily, there is a simple and inexpensive solution to get those old 7.65 Mausers shooting again and all it takes is some trimming.1891 72

Belgian 188972

If you start with fresh .30-06 brass that hasn’t had a chance to work harden after a few firings you will be ahead of the game in terms of case life.

Remove the expander ball assembly from the 7.65 Mauser die.

Remove the expander ball assembly from the 7.65 Mauser die.

 

Apply a small amount of lube to the outside of the case, well down from the shoulder. Too much lube on the shoulder or case body will cause pressure dents.

Apply a small amount of lube to the outside of the case, well down from the shoulder. Too much lube on the shoulder or case body will cause pressure dents.

Run the .30-06 case up into the die to the top of the ram stroke for your first test case.

Run the .30-06 case up into the die to the top of the ram stroke for your first test case.

 

Here is the formed case. It just needs to be trimmed to 2.090" and you will be ready to make some measurements.

Here is the formed case. It just needs to be trimmed to 2.090″ and you will be ready to make some measurements.

Chamfer the case after trimming and run it up into the action.  The bolt should close with mild resistance.  If it closes easily, it may be necessary to re-adjust the full-length die to move the shoulder ahead a few thousandth of an inch to get a firmer datum on the headspace.  In our test rifle, simply setting the die to contact the shell holder created adequate headspace.

Cases after forming, trimming and a loaded factory 7.65 cartridge.

Cases after forming, trimming and a loaded factory 7.65 cartridge.

Once you are confident regarding the shoulder position, load the dummy to get a good neck diameter dimension.  Cases that are resized with brass below the shoulder sometimes develop thick neck dimensions.  In this case, the dimension was consistent with the loaded Norma round we had in the lab.  Case necks need about .003″ smaller than the chamber neck dimension to release cleanly into the bore.  The best comparison would be made with a cerrosafe casting of the chamber neck, but comparing it to a standard production cartridge neck should produce a safe test load.

Factory loaded 7.65 and a 7.65 formed from .30-06 flank two reformed .30-06 cases.

Factory loaded 7.65 and a 7.65 formed from .30-06 flank two reformed .30-06 cases.

 

If the dimensions look good, you are off to the races.  Load the next resized case with the minimum load and fire it.  If you are still conscious, measure the neck diameter and add .001″ to your number and that should provide a reasonable approximation on your chamber neck dimension.  Compare that to your dummy load and confirm that dummy round’s neck is at least .003″ smaller.  If it isn’t some neck turning will be necessary, but it wasn’t in our rifle.  Once the test round has confirmed that everything is working well, the sizing and trimming process can begin in earnest.

Trimmed, chamfered and ready to load.

Trimmed, chamfered and ready to load.

Chances are that all you will need to do is lube a .30-06 case and resize it in the full-length sizer die, trim and then chamfer in order to have a supply of good quality, reasonably inexpensive brass for that old Mauser.  It isn’t much work and they are truly a joy to shoot.