8mm Mauser load data

[Liam]

Prepping an old Mauser for a shoot on Sunday. Grabbed ammo I had loaded years ago and, as usual, I verified the load data to ensure it was loaded to acceptable levels. Just a little second check I like to do. Well, I must have only owned the Speer #14 loading manual at the time of loading. I now have the Lee 2nd edition loading manual to check against. I discovered quite a difference in the suggested "Start" loads and "Max" loads from these two manuals. The rifle is a 8mm JS Persian Mauser in good form/function manufactured in the 1930's. For a 150 gr. jacketed bullet, the two IMR4895 parameters are:

Start Max
SPEER 44 gr. 48 gr.
LEE 31.7 gr. 36 gr.

Quite a difference! Since I usually split the difference between the start and max, I had loaded the ammo with 46 gr. of IMR4895. Is the Lee manual this conservative across all calibers? Perhaps someone here uses the Lee manual and yet another loading manual and has noticed something similar.

[JOHN COOK]

This is info from Lyman 49th Edition Loading manual. They show for a 150 grain bullet Jacketed SP , IMR 4895, 44 gr. . Max. 49.2...
They state this is for 8x57mm ( aka 7.9x57 and 7.92x57) German military cartridge with the .323" diameter bullet. IT is NOT for use in any rifle with the older .318 ' bore. For what its worth, lyman has nearly a full page with information concerning this round. States, it has caused a lot of confusion to American shooters. It appears to me , in reading the information , the bore started out .318" diameter and was changed to .323" Diameter. They then state that in 1905 German military adopted .323" and all rifles manufactured since then has the .323" diameter JS bore.. ( What ever that is)

CAUTION.... CAUTION..... CAUTION..


This is for your information only. Don't use the numbers posted to reload until you verify it personally ...

john

[togor]

Yes, I agree with Mr. Cook. The Lee data appears downloaded on the chance that someone is shooting that load out of a Gew. 1888 rifle. As someone once observed, US commercial ammo for 7.92x57mm was loaded practically to 30-30 specs (perhaps to keep the lawyers happy). Hodgdon's online data center shows a start/max with IMR4895 with a Hornady 150gr SP bullet as 42/49.5. So your 46gr is in the ballpark. Personal protective equipment is always a great idea, and the best safety is between the ears. Good luck!

[Liam]

Cheers gents! Yes, the newer iteration 7.92x57/.323 is what I have. I have actually slugged the bore to be sure. I must have wrestled with this the 7 or 9 years ago when I actually loaded the ammo (but I don't recall). I will shoot the ammo come Sunday...with proper eye protection as is usual for me.

[Tuna]

I just checked my old Lyman 45th edition manual. For a 150 gr. bullet with IMR 4895. Starting load is listed at 48 grs. for 2688 fps and max. load of 51grs. (compressed load) for 2824. All from a 23 inch barrel. This is of course before lawyered reloading manuals came along. The Lee manual is very much printed with lawyers in mind.

[Sunray]

Lee tests nothing themselves. They republish Hodgdon data for Hodgdon powders. I'd be guessing that's may be a typo or very old data. The Lee 2nd Edition manual was first published in 2011. Revised in 2016, but that doesn't mean Hodgdon had retested the 8mm Mauser. That data is quite possibly much older than 2011 too.
Current data on the Hodgdon site shows 42.0 to 49.5 of IMR4895 and a jacketed 150.
A Gew. 1888 rifle made after 1905 uses the same data as a K98 made in 1945.
Mind you, so does any rifle with the older .318" bore. The M88 was loaded with 42.4 grains of a single base smokeless powder. The only difference between 'em is the bullet diameter and that the original bullet was a 225 grain RN at 2,034 FPS. Current 220 grain start loads run close to that.

[jjrothWA]

Recently spoke with Sierra bullet tech, regarding a CV-27 in 7.9mm Mauser,
he recommended using the 175 gr spitzer bullet and 4064 powder, starting abut 43grs up to 49 grs.

The "JS" refers to the standardization of the .323 diameter bullet and barrel for thta bullet, some of the Gewehr 88 Commission rifle did not get the new barrels. still require the .313 bullet.