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I am getting ready to build my Siamese Mauser but i would like to know what barrel twist to use. I have bullet mold from 350 grains to 500 grains. Who makes a pre thread barrel to fit my action. Parts are getting really hard to find for the Siamese. I found a brand new sported stock on e-bay i been searching for months for one.
I have 3 45 cal rifles 2 45-70s and a 45-90. All have 1-18 twist barrels. I haven't shot any light bullets but mostly bullets in the 500 - 550 grn range over black powder. I would recommend a 1-18 twist for your project. My barrels are 1 pedersoli, 1 green mountain and one BRC. A pedersoli take off could possibly be refit to your mauser action and recontoured. As to barrels douglas, shillen, Lilja, Pac - Nor all make blanks.
Try E.R. Shaw, www.ershawbarrels.com for a pre threaded barrel. they have made up hundreds of Siamese Mauser into 45-70 rifles. Also be very careful when you open up the mauser extractor to work with the 45-70 round. If you screw that up you may have a very hard time finding another extractor. I have a Siamese mauser in 45-70 that some one open the extractor claw too much and it took me a year to find another one. E.R. Shaw can also do the extractor work for you if you need that done.
ER Shaw did my 45-70 for me many years ago, 30+ I’m guessing. It has a Bishop utility grade stock that is completely glassed in and spray painted with an automotive wrinkle finish paint. All the metal was parkerized by Texas Armament. It has a Williams peep on the 20 inch barrel. Neat part is I also have a 45 ACP chamber insert for single loading. It actually will hold a 6 - 8 inch group with cast 45 ACP loads at 50 yards.
Not a 45-70, but my .458 Socom (mild semi auto 45-70 equal) has a 1-14 that shoots the 300 grain bulets accurately.
bouncer50
I built my Siamese Mauser 450-400-70 (45-70) back in '74. I used a pre-threaded long chambered "Star" barrel (ER Shaw now). It has a 22" twist and stabilizes all my cast bullets from 210 to 500 gr at velocities from 500 fps to 2300 fps. I shoot jacketed bullets of 300 to 405 gr from 1300 fps up to 2500 fps. I shoot the Barnes 400 gr Original SP at 2300 fps. I throated the chamber to fit that round loaded to just under magazine length which essentially gives the case capacity of the 45-90 cartridge, just less than the 458 Win Mag.
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Here is my 1871 Mauser in 45-70 Black Powder.one in twenty twist.It started life as an action and furniture I fitted it to a used Stock.I Rifled the Barrel using a whitworth Barrel as the Rifling Guide.It has Six Grooves and took many hours to cut and lap the rifling.
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Another view of the Model 1871 single shot rifle.The forerunner of the 71-84 model that had a tubular magazine.I had the rifle proofed at the Birmingham Gun Barrel Proof House.