Thumper gun project

OntarioHunter

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I started this project back in April. I'm building a 404 Jeffery on a standard Mauser 98 action (BRNO vz.24). Mostly did it for the challenge ... and the history. Jeffery designed this cartridge in 1905 to be the first elephant gun rimless cartridge specifically for the relatively new Mauser repeating rifles. Up to this time essentially all the dangerous game cartidges/guns were double rifles. Besides the disadvantage of only having two rounds loaded, double rifles were exceedingly difficult to manufacture and therefore exceedingly expensive. Jeffery designed a big bore to fit in existing Mauser 98 design actions. He did this by cutting away the sides of the 8mm magazine box, opening the wood to hold three wider 404 cartridges, moving the feeding ramp forward into the front ring, opening the bolt face (to accept wider 404 rim), and modifying the feeding rails. It worked. Jeffery was able to produce big bore rifles relatively cheaply that were plenty powerful enough to kill dangerous game effectively. Initially Jeffery offered ammo in both 300 gr and 400 gr, the latter screaming along at 2130 fps. An added bonus was (and still is) relatively mild felt recoil (relative to typical 500 to 700 Nitro Express double rifle elephant guns). Jeffery's main competitor Rigby was keen to capitalize but was wary of building anything bigger on a standard length action. So he requested that Mauser build him something larger and stronger for his new 416 cartridge (which he originally did fit into a standard Mauser 98). And thus the magnum action was born in 1913.

I chose a different path than Jeffery. I ordered bottom metal (trigger guard, floor plate, magazine box) for 416 Remington magnum from Blackburn-Swift (of Swift Ammunition). I planned to widen the box slightly to meet Paul Mauser's cosine of 30 degrees formula but it appears I can get by with it as is. I used a Dremel tool to grind open the belly of receiver to match the shape of Swift box. Then the feeding ramp needed to be moved forward into the front ring, again using a Dremel grinder. A Timney trigger was installed easily but getting it to match up to Model 70 style 3-position safety and shroud from Parkwest proved to be a challenge. I think most of the problem was due to modifications to cocking piece done by previous owner, presumably to make the trigger with safety he installed work (the military safety and trigger was back in the action when I bought it but cut out on bolt shroud ring indicates a side mount trigger block safety must have been in the gun at some point). On close examination I discovered a crack in military bolt shroud so I decided to go with expensive new 3-position safety. Turns out previous owner slightly warped the back end of the bolt when he welded on a new scope relief bolt handle. I fought the installation of new shroud and safety for several days before discovering the source of the problem. I was finally able to cure it by very slightly reshaping/polishing the striker which was binding in the new shroud. I bought an old new stock that had never been installed. It has a side safety cutout that I'll have to fill. Got a good deal on the stock, it's a good stout design/wood, and the old fella could use the money (we made the deal in parking lot of hospital where he was getting treatment). A good piece of wood to use as a learning tool. I'm right now waiting for Lidja of Plains, MT to finish the barrel. Owens, also of Plains, will thread, ream, head space, and crown it. I will finish bedding the action and tuning the feeding rails (Owens resolutely refuses to do that). I will also attach the Winchester Model 70 Express iron sights exactly the same as on my Springfield. The rail is also nearly a duplicate of the one on the Springfield. This gun will wear the Sprinfield's 1970s retired 3x Weaver scope, also with Warne QD rings. Then the 404 should be ready for Africa. I may have time to get it blued before leaving in August but I doubt it. If not, everything will be in the white except receiver, scope, rings, and iron sights. Yesterday I added the zebrawood fore end cap. Made it from a blank. Today I plan to make a grip cap to match. The lightning bolt pattern in the grip cap has given me the idea of naming this gun Thor's Hammer. Naah! New England Custom Gun furnished the magnum length follower, although standard length one that was in it worked fine. I also ordered a Cape buffalo ammo wallet to hold five rounds on my belt. Very nice quality and a good price. No flap on this one as I don't want to deal with that if I have to load quickly before getting stomped to death. I will probably also start applying Linspeed oil finish to the stock today. It should require at least a dozen coats.
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I hope this rifle will see real Africa and not just another South Africa shooting farm. I have been some places that there have been times where I wished I was holding a thumper instead of a .375.
 
My hunting experiences in South Africa have been more than satisfactory. I enjoy visiting with and often even staying with farmers and their families. I have made lots of friends I enjoy seeing again and again. And some of the properties are huge. The game is plenty wild ... and lots of it. I enjoy hunting ranches in Montana too. Not much different. Have never hunted the "wild" areas of Africa but I've certainly had my fill of wild places on this side of the pond. "Wild" is often overrated ... and usually greatly overpriced.
 
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The Mauser's new barrel would not group so I've been frantically trying to sort that out. Took some gas out of the loads and that seems to have done the trick. Bullets now touching at 100 yards (they're big bullets!). It's too late to get the Mauser blued. Maybe after hunting season. For such a heavy gun, it sure has a lot of recoil. First time in my life I've suffered a Wetherby eyebrow.
 
Had to do a bit more fine tuning on the follower, loading ramp, and extractor. Last shell could be sticky loading. I decided it made more sense to carve on the follower than the receiver's rails. Take too much metal out of the follower and I can just replace it (the original standard length follower could always go back in). Take too much metal from the receiver rail and I'm pretty much screwed. The loading ramp was just a little too tight. Extractor wasn't consistently snapping over on cartridges dropped into the chamber. Kind of important to get that worked out on a 3+1 dangerous game rifle. Don't want the first shell stuck in the chamber if a wounded buffalo is charging. Again, taking too much metal means simply tossing the extractor and starting over. But I don't have an extra extractor on hand. Easy does it.
 
My big bore 404 Jeffery made it to Africa but had to go "in the white" as there was not enough time to get it blued. I spent several days chasing Cape buffalo with it but never able to pop a cap. Finally got it back from bluing this week. While it was gone I finished up the stock. It only had two coats of Linspeed oil before leaving for Africa. Added at least ten more. I put it back together and ran it through a very rigorous "dangerous game" test. Cycled it fully loaded through about fifty reps without a hitch. That included "snapping over" on first round dropped in the chamber. It only holds three in the box so snap over controlled feed feature is kinda important, especially for fast reloading when a seventeen hundred pound angry specimen of "black death" is about to stomp me to death. Modifying an 8mm action to properly feed and cycle 404 cartridges is no mean feat. First time I ever tried it and the end result, a rifle that cycles smooth as glass, is an accomplishment I can be proud of.
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This thumper may not be a tack driver but definitely minute of buffalo. Target lower left is the 404 (center target is my 30-06). Hundred yards.
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Beautiful rifle/project. About 20yrs ago I had one built on a Mod 98 action by a local Smith. Ordered a Safari Synthetic by now defunct Harris Gunworks, Az. NECG irons only, no scope. I felt the .404 "kicked like a .375 but hit like a 458". My buffalo hunt fell through, so I gave the rifle to a Missionary friend who was going to Australia, goal was to take a big Sweeper Bull. As in the 9.3x62, factory loads had a few failures to fire I was too OCD to just use factory loads, rather loaded my own, set up hunting loads in once fired, properly headspaced cases. That long sloping shoulder was only aggravating complaint on the Jeffery. It was an enjoyable experience anyhow.
 
Beautiful rifle/project. About 20yrs ago I had one built on a Mod 98 action by a local Smith. Ordered a Safari Synthetic by now defunct Harris Gunworks, Az. NECG irons only, no scope. I felt the .404 "kicked like a .375 but hit like a 458". My buffalo hunt fell through, so I gave the rifle to a Missionary friend who was going to Australia, goal was to take a big Sweeper Bull. As in the 9.3x62, factory loads had a few failures to fire I was too OCD to just use factory loads, rather loaded my own, set up hunting loads in once fired, properly headspaced cases. That long sloping shoulder was only aggravating complaint on the Jeffery. It was an enjoyable experience anyhow.
What problems did you have with the 404 Jeffery's long sloping shoulder?
 
What problems did you have with the 404 Jeffery's long sloping shoulder?
Some brands of factory ammo or brass had headspace issues. Took two strikes to go off, etc. My chamber was cut right, I just had to fire form my cases first, then work up a good load. The CZ 550 FS took two strikes with the Barnes Vortex similar 9.3x62 also. Same sloping case, which is fine for cycling the rifle, just need to check headspace, case dimensions.
 
Some brands of factory ammo or brass had headspace issues. Took two strikes to go off, etc. My chamber was cut right, I just had to fire form my cases first, then work up a good load. The CZ 550 FS took two strikes with the Barnes Vortex similar 9.3x62 also. Same sloping case, which is fine for cycling the rifle, just need to check headspace, case dimensions.
Thanks. I had problems with RWS brass being short in length and inconsistent rim thickness. Hornady brass is working fine.
 
At the time, I was a very devoted fan of my Mod 700 Classic in 35 WAI. I spent my time FF brass for it. I had it tricked out in a Brown Precision High Country, braked ( installed when I had my neck fusion, just left it on) 1.5x5 Leupold, Decelerator pad. Shilen Trigger. Killed alot of game with it. I had my loads pretty hot and I didn't want to gamble a problem with my only good eye, my shooting eye! ha. I just moved on, sold it all pc meal. I like to experiment, but I have a limit on rifles. I gave the CZ 550 FS to my German Descent SIL, and when the Barnes Vortex clicked he just threw another in, killed the mean hog! I liked the Ruger African 9/3x62 and really should have kept it, but was raising money for a UP, MI hog hunt. Sold it. I used the Woodleigh 310sn/@2400 with that Whelen...9.3 country! Good luck to you.
 
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