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98 Mauser in 300 weatherby

khornetkhornet Member Posts: 115 ✭✭

A guy wants me to sell some guns for him, all 30-40% but as usual his finger stops at the NIB price. He has a 98 Mauser that has been rechambered to 300 Weatherby mag, I'm trying to convince him that this is an unsafe gun due to pressure difference between 8mm and 300 Weatherby. He thinks it OK but I worry about liability selling this. You have to wonder what gunsmith would think this is safe. What's your opinion?


  • MIKE WISKEYMIKE WISKEY Member, Moderator Posts: 9,750 ****** depends on the make and year of the action......weatherby actualy started making rifles useing f/n m-98 actions before bringing out the mark 5. I've never heard of any problems with them.

  • navc130navc130 Member Posts: 1,017 ✭✭✭

    As I understand it, it is not the pressure of the magnum cartridges that limit their use in 98 standard length actions. In order to feed the longer cartridges the feed ramp, which is the rear of the lower locking shoulder, must be cut back. This weakens the action. For that reason rechambering to magnum length cartridges is not recommended. The commercial Mark X action is chambered for .300 Magnum. The Mauser Magnum action is only longer, not any stronger. My impression is that it was a common practice to alter the 98 action to magnum length cartridges in the "old days."

  • MobuckMobuck Member Posts: 12,966 ✭✭✭✭

    I wouldn't shoot it myself. Yeah, I know this conversion was done frequently BUT having sustained permanent and life changing injuries from a 'blow up' involving a P17 action(considered 'stronger' than M98) re-barreled to 257WBY it's not worth the risk. After recovering from the action failure, I sold/traded away EVERY 'sporterized' M98 I had that was chambered for a cartridge of significantly higher working pressure than standard 8x57.

    From that time all my Mausers were built on Mark X actions.

  • khornetkhornet Member Posts: 115 ✭✭

    there are no marking of any kind on the action, it is a military model with the thumb cut for charger clips.

  • asphalt cowboyasphalt cowboy Member Posts: 8,855 ✭✭✭

    The only Weatherby magnum I know of that would be safe in a milsurp 98 action is the 240 Wby. With a cartridge the length of 300 Wby, I wouldn't touch it with a ten foot pole. To shoot or sell.

    The milsurp actions were case hardened with the hardened case being, IIRC, .007"-.011" thick. Just a WAG on my part, but I'd think you would need to remove at least .125" of material from the feed ramp to get a cartridge that long (300 Wby) to feed.

  • MIKE WISKEYMIKE WISKEY Member, Moderator Posts: 9,750 ******

    " I'd think you would need to remove at least .125" of material from the feed ramp to get a cartridge that long (300 Wby) to feed.".................but the removed material isn't the 'working' part of the action. I'm not defending the conversion or condeming it either, just noting there are other considerations. in 'high' end conversions having the action re-carberised is common, there are several heat threating companies that do this.

  • AmbroseAmbrose Member Posts: 2,999 ✭✭✭

    As has been said, Roy Weatherby started with whatever actions were available, mostly FN's, but probably 98's as well and they would have to have been modified to accept the longer (3.562") and wider cartridge. The pre-64 Winchester 70 was chambered for the H&H cartridges and I was surprised to see that they were built on a modified standard (.30/06) length action. I had taken my .300 H&H out of the stock to clean it and adjust the trigger and it was evident what the factory had done to make it work. A longer by .200" and wider magazine box, a wider; to the right, (but not longer) follower. Considerable steel removed from the feed ramp area and also the rear of the receiver ring which, of course, reduces the material that backs up the locking lugs. Steel was also removed from the front of the bridge but the rear of the magazine location remained unchanged. The bolt travel is the same as the .30/06. With the factory making these changes, the necessary heat treating and testing would be done in contrast to what an ordinary gunsmith would be able to do.

    In contrast, when the Remington 721 first came out, they too were available in .300 H&H and I was surprised to see that they had a true magnum length action. I discovered this when I couldn't see any difference dimensionally between my .300 and my .270. So I tried a .300 cartridge in the .270 magazine. It snapped right in! I tried the same thing with a .30/06 Remington 700--same thing; snapped right in!

    Now before we start an argument about my rifles having been tampered with, don't take my word for it, check it yourself with your rifles.

    As to the safety of the OP's conversion, I don't believe I'd trust it. There's no way to tell the quality of the work and the assessment by the OP of 30-40% condition does no bode well, either.

  • asphalt cowboyasphalt cowboy Member Posts: 8,855 ✭✭✭

    But it is part of the "working part". Without the rear area cased the softer inner steel can be deformed (hammered back). Eventually both lower and upper surfaces will set back causing, at minimum, excess headspace and at worst a catastrophic failure.

    Yes, it can be, and may have been, re-carburized. Without documentation I wouldn't touch it.

  • MIKE WISKEYMIKE WISKEY Member, Moderator Posts: 9,750 ******

    well, they say a picture is worth a thousand words.

    the black outline around the bolt in the upper part is the approximate depth of the 'pack' case hardening

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