Answer

Even though they are the same size, the difference is in the pressure. The 7.62×51 is limited to 50,000 psi MAX pressure, this is much lower than the pressure of commercial 308 Win. I reload all my 308 to 7.62×51 specs, just to be on the safe side. The Mauser was built for a diet of ammo with pressures in the 33,000 psi range. Bill

Answer

The K98 can handle .308 or 7.62×51 as far as the pressure, at least the large ring Mausers can. If I remember, the 7.62×51 is loaded to a max of 50,000 psi and the .308 to a max of 62,000 psi, so they’re not radically different. I’m not sure I’d convert an early Mauser, steel might be a little softer in the receiver, but all the Argentine, Chilean and even Yugo Mausers should be fine. Get your barrel for a .308 and you can shoot both, now days 7.62×51 is manufactured to the same specs as .308 is, the slight difference in the shoulder that changed head space is really a thing of the past. It’s kind of like the .223/5.56 debate.

The issues with Mauser conversions are usually magazines and/or followers causing feeding issues. The 8mm Mauser, 7.62, 30/06 and .308 are all really the same bolt face, though cartridge lengths change. Probably because they’re all based on the same family of cartridges. There were a ton of .308 conversions, especially by the Spanish, even of early guns. There are a number of countries that built Mausers in .308 or 7.62×51 as well.

I’ve been toying with converting my Yugo Mauser to 30/06 but I may look at a .308 for it now. Either is a heck of a lot easier to find than 8mm Mauser ammunition. 🙂

Ken will likely have some advice here too, I’m sure he sees a lot of Mausers in lots of configurations. Jeff

Question Follow Up

I thank you both, I will go with .308 on my build. I would leave it an 8 mike mike if it had original German markings. So I am going .308 because of ammo and I want a rifle that can stand max pressure. My last build was an AR15 chambered in 5.56×45 mike mike, which started as a 0% casting that I picked up at Knob Creek, I did away with gas impingement and put an Adams Arms Piston system which I would recommend. Counting tooling and parts, got about $2000.00 in it.

Answer

The 98 Mauser can handle the pressure with no issues. Remember they were shooting 8×57 ammo and a lot of that was machine gun ammo, not to mention the high pressure sporter rounds the 98 came chambered in. Regardless it is a very strong action and I wouldn’t worry about it……..as long as it is breeched up correctly and all the other stuff is correct as well. What make is your 98? You may want to get it reheat treated if it is one of the softer/poor tempered versions. Ken