Forums.NitroExpress.com

Hansol, I will be in the shop Monday and take a few photos.

I found the 50-110 and 500 Nitro cases today.

I also have some modern day load data, with pressure and velocity readings, for a 50 caliber single shot rifle I was working with a few years ago. Basically a 50-110 in a modern receiver loaded to around 45,000 psi. 5,265 ft lbs with a 450 grain bullet. With another 1/2 inch or so of case length this will fit in an Enfield and run up to around 7000 ft pounds if I remember correctly. Should do nicely for a cape buff. I ran some Quckload predictions of this combination, it is very impressive. I will dig out the data. I terminated the project with the 50-110 case, as I was afraid someone would get their hands on one of the cartridges and fire it in a 1886 Winchester or one of the old single shots. Instant blowup.

Facing the receiver ring: The stripped receiver is mounted on a threaded mandrel, precision turned with centers to fit the lathe, and a snug fit both on the receiver threads and inside the bolt run. Then the front of the receiver is turned true so it is both at a 90 degree angle to the axis of the receiver in all quadrants and to provide a flat, smooth surface for the barrel shank to butt against. We need this, as if the receiver face is not true, which in factory and military arms the face is not true, then as the barrel expands on repeated shots, the barrel "walks" and the muzzle drifts, giving poor grouping on the repeated shots. Very important to face the receiver ring in target and extreme range rifles, and it is a good thing to do on all hunting rifles. Takes all of 5 minutes to do in the metal lathe if the gun builder is properly equipped. I will take a photo of the setup, the old statement "A photo is worth a thousand words" applies here. This is why I use a 1.300” diameter barrel shank, gives me a lot of bearing surface against the receiver ring.

Barrel Recoil Lug Attachment: I make the lugs in my shop. The lug is machined for a close fit to the barrel contour and is attached with two no. 8-40 high strength screws and Brownells HiForce silver solder. HiForce has a tensile strength over 30,000 psi, melts at around 400 degrees F, and will withstand bluing salts. I also use HiForce for attaching the barrel band front ramp, the band swivel lug, and the rear sight island. The operating temperature of the silver solder does not damage or bow the barrel; I can place my fingers on the barrel a few inches away from the silver soldering area when attaching the lug. The trick is proper fluxing and tinning of the barrel and the lug before attaching the lug to the barrel. The two screws both align the lug when soldering and provide a clamping action when tightened before the solder cools and sets up.

The barrel lug on the original A-Square Hannibal (I had a 510) was TIG welded on. The barrel on my Hannibal was bowed 0.045” at the recoil lug area, a consequence of the high heat associated with TIG welding. Guess what this does to accuracy!

RE the 510 A-Square: In Hatari Times No. 22, Harald Wolf says: “We did a few velocity tests on A-Square cartridges and found them considerably slower then advertised.”

However, the 510 A-Square is still a very powerful cartridge even at slower than advertised velocity.

As you may gather from my rambling posts, I have expended considerable time over the years researching and building big bore rifles. I have tried to assimilate the best ideas from all in putting together my rifles, omitting the unsound techniques. From my industrial machining background, I like to use the term “Brute Force and Ugliness” in constructing big bore rifles, both for what comes out of the barrel and my somewhat robust method of big bore rifle construction.

Cheers and have fun on the project!

Edited by Altamaha (01/02/10 02:51 PM)