Thread: 7.65X53 Mauser Chambers, dies, brass, ammo and case forming

Retrieved: 08/20/2016
Last Post: 01/03/2016

This is some of the data that I have gathered from 7.65 Mauser rifles, dies, factory ammo and new factory brass.

Keep in mind that there are NO SAAMI standards for this round. However there are CIP (European) standards for this round.

Because CIP drawings use a different scheme to dimension the drawing I had to change the measurement units to inches and calculate the Gauge dimension using trigonometry in a spreadsheet. The CIP drawings are not toleranced unless there is a seperate reference document so I calculated my own SAAMI go and no go and field dimensions for my own use.

If you are more interested in the subject you can read about the delta L problem with some cartridges. The delta L problem exists where the longest ammo permitted, by the standard, is longer than the shortest chamber permitted in the rifles. This means you could get ammo that is in tolerance that will not chamber in rifles that are also in tolerance. This is not really good engineering practice. Just do a web search for "delta L problem".

Gauge = The dimension from the head of the case to a .375 gauge diameter on the shoulder.

The measurements were taken with a .375 gauge bushing mounted on a set of dial calipers.

The calipers were set using a 7X57 Forster gunsmith headspace gauge. They were set using the dimension marked on the gauge.

This provides for a very accurate gauge setting.

For the rifles I sized a fired .270 Win case until the stripped bolt body would close with a very slight drag.

This case was measured with the gauge set up above. The result is what I considered the chamber length for that rifle.

Notice how uniform the results are.

Rifle      Cal     Gauge
M1891      7.65    1.822
M1891      7.65    1.821
M1891      7.65    1.820
M1898/09   7.65    1.820

Note that Norma is somewhat shorter. Norma ammo was not as consistent as PPU.

The new brass of each brand was very uniform. The 4th and 5th decimal places came from calculating the averages.

Norma ammo will stretch about .010 worst case when fired in my rifles.

                        Gauge                        Gauge
Norma Factory Ammo = 1.812-1.816    Norma brass     1.81520
          PPU ammo = 1.819 -1.821   PPU brass       1.81775

.001 increment guage pins - for the neck and base diameter of each die

Brown & Sharpe 0-1 micrometer - Shoulder diameter and pressure ring diameter produced on cases sized by the dies

Caliper with .375 diameter gauge bushing attached - Sizer Headspace = head to shoulder length produced on cases sized by the die.

The last 3 columns are just the GO, NO GO and Field dimensions that I decided upon based on the rifles, the ammo and dies.

These are my preferences based on the data. You are free to use your own calculations.

           RCBS   Die     Die   NECK   SHOULDER  BASE  Pressure GAUGE  SIZER                   FIELD
Cartridge  Code   Brand   TYPE  DIA.     DIA.    DIA.    Ring   DIA.  HEADSPACE GO MIN  NO     MAX
                                                         Size                   MIN     GO
7.65
Mauser            CH      TRIM  .3360   .4260   .4690   .4670   .375    1.7810  1.8160  1.8200  1.8240

7.65
Mauser            Pacific FL    .3360   .4250   .4710   .4660   .375    1.7970  1.8160  1.8200  1.8240
                                      
7.65 
Mauser            Lyman   FL    .3320   .4230   .4670   .4660   .375    1.8140  1.8160  1.8200  1.8240

7.65 
Mauser     66     RCBS    TRIM  .3390   .4280   .4690   .4670   .375    1.8160  1.8160  1.8200  1.8240

7.65 
Mauser     88     RCBS    FL    .3310   .4300   .4670   .4650   .375    1.8180  1.8160  1.8200  1.8240

7.65 
Mauser     N      RCBS    FL    .3290   .4250   .4690   .4660   .375    1.8190  1.8160  1.8200  1.8240

7.65 
Mauser            LEE     FL    .3250   .4250   .4710   .4660   .375    1.8380  1.8160  1.8200  1.8240

Some dies will require some extra time setting them up to maximize case life.

Notice the old CH and Pacific dies are too short and the Lee die is too long. The Lyman is a little under my min chamber length and the RCBS dies are just about perfect.

runfiverun
12-29-2015

Well that would explain why I use LEE dies for one rifle and RCBS for the other two.

The Lee dies are too long for #2 and #3 but just right for #1.

When making brass I make it all in the LEE die set and TTL.

Then re-run it through the rcbs set as needed and keep everything separated after the first firing.

EDG
12-29-2015

I have a lot of dies and form a number of cases.

Setting and resetting the dies for different rifles is tedious if you want the cases to match the chamber to within .001. Since I have more rifles than dies in most cases I did not want to be setting and resetting a single die for each rifle by feel only. I have a Wilson gauge that can check cases also but it has some limitations. So I bought the Hornady gauge to measure the head to shoulder lengths. By using formed cases to transfer the shoulder length of the chamber I can get a good idea of the lengths of both chambers and sized cases so I can make them match. I am also recording all my chamber lengths.

I had been using telescoping gauges to measure the necks and base diameters. Then I bought a set of .251 to .500 .001 increment gauge pins to make the measurements less tedious. I had been recording neck diameters for a long time for all of my dies to use as a reference for case forming.

I now have a large spread sheet with the data from these and many other dies. Some of the data is very useful for case sizing and forming. I will eventually measure the chambers for all of my rifles.

I learned a lot from the 7.65. The main thing I learned is, the best way to know what you have is to measure it with a reliable method. Once you have the numbers, you can easily understand what is going on.

Mk42gunner
12-29-2015

Seems strange that there are no SAAMI standards for this cartridge since Winchester made a few model 70s chambered for it; and I seem to recall they also made some model 54s, I could be wrong on that memory.

It would be interesting to see what a Belgian or Turkish Model 1889 Mauser chamber measures compared to the Argentine ones.

runfiverun
12-29-2015

They did make some model 54's in the x54 round.

It's probably their most sought after rifle.

for the argies it's hard to beat the 314299 sized to 313 on to of 16grs of 2400.

I have measured the throats in all of mine and they are stupid huge.

I have an Accurate mold cut to a loverign design that's about 2,000 grains heavy and it still don't hit the end of the throat even seated out to just about falling out of the case.

leadman
01-03-2016

I have 4 of these rifles and only 2 will interchange ammo. I use the RCBS trim die to reform brass and an RCBS Belgian 7.65 X 53 die set to load with. I reset the sizer die to just touch the shoulder on brass kept separate for each rifle. I do try the first case sized in the gun to make sure it will allow the bolt to close easily.

I have known about the different dimensions of the chambers for this cartridge for about 25 years but has not been a problem for me. My normal practice for just about all of my rifles is to partial size for brass fired in the same gun. If a gun seems to have a chamber that is on the long side I fire form it with COW and a fast powder first as this extends the life of the case.

There is still some of the military surplus look a like ammo that was loaded by a commercial company in South America on the old machinery that was worn out. I bought some of this when it first became available and it was difficult to get the bolt to close on it. I recently was given some with the purchase of another 1891 but plan to break it down for components.

I read in my book on these guns that each rifle purchased had 3 additional barrels with it. I have bought 2 NOS barrels and both were very close on the headspace but not correct. The last barrel I installed is short but I placed a .020" feeler under the case in the sizer die and cam the RCBS press handle over and it fits fine. The gun is very accurate but my plans are to rent a reamer and make all 4 guns have chambers as close as possible.

I also read that the bullets the Argentine factory loaded for these guns had a .311" bearing surface except for right at the base which was .313".

Interesting post by the OP and confirms what many here have suspected about the chambers and die sets. With old mil-surp guns I fire form the brass to the chamber as long as it is safe and keep the ammo separate. Also tend to do this with my commercial guns.

vzerone
01-03-2016

Back many years ago (many) Speer use to offer their j-word bullet for the 7.65 Argentine and it was .313. Everyone else at that time had bullets either .311 or .312. After some time passed Speer changed their diameter to .312. I wondered why and thought probably to prevent some product liability law suit if someone used them in tighter 30 caliber bores. Too bad, those .313 Speers shot very well.

I have a 1909 Argentine rifle in very good shape. The barrel appears almost new. When I got it I slugged the barrel and it has a .311 groove on the button! I was very happy with that indeed. It shoots very good. Most the 1891 carbines I own almost always had groove diameters of .313. Interesting too I have a 7.7 Japanese short rifle that has a .311 groove also. I'm fortunate with that one too.

That's interesting about the NOS barrels you mentioned. Where did you ever buy those from?

leadman
01-03-2016

I used to find those Speer .313" bullets at gun shows but not anymore. I called Speer and they have no intention to make these again. I believe the new Speers are .311" diameter, with the Hornady being .312". The Hornady 150gr .312" gives me 1.5" groups at 200 yards.

I bought the first NOS barrel about 15 years ago from SARCO, the other I bought off E-Bay or Gun Broker about a year ago.

I have 3 Type 99s that all have bores around .314". They shoot well with boolits.