If you ask any military surplus collector "What is the most iconic pistol of WW1?", chances are 90% of them will reply "The C96". It's been a staple of war movies, science fiction, video games, and real life for over 120 years. The aggressively boxy lines, odd magazine configuration, and combination stock/holster give it an air of elegance that has made it a favorite among multiple generations across multiple continents. One of the biggest fans were the Chinese who referred to the C96 as the "Box Cannon". It was a status symbol and a primary fighting weapon of many during the Warlord Era, leading many of them to be used significantly beyond their service life. During the 1980's and 90's, large quantities of these tired C96's were imported from China in an array of conditions but mostly on the poor side. Cracked bolt stops, dead springs, handmade replacement parts, and rotted frames are typical of the Chinese imports but the most common ailment of them all are bores worn smooth. Not even a trace of rifling is present on most of them as a result of being shot with corrosive primed ammo with no real cleaning ever performed.  Chances are if you've come across a C96 that's sub $1000, its one of these Chinese imports with no rifling to speak of. Seeing as they are the last source of reasonably priced 96's it is a shame that almost none of them get shot. 

      The example that I used in this project has been around the block several times. When I got it, it needed new springs all the way around and a bolt stop. For curiosity's sake, I did shoot it with a few magazines of 7.63 Mauser and unsurprisingly it couldn't reliably keep a 5' group at 10 yards and so I tucked it away as a rainy day project for several years. Very recently I made a batch of LF-57 barrels and ended up with some left over 9mm blank - this was the sign I needed to get that old warhorse back out on the range. 

Traditional Techniques

      As I've previously covered in the ZB30J Project and the Steyr 1888/90 Project, sleeving worn out barrels is not a new process and has been around for quite some time. For a very long time, that's how C96's were refurbished along with overboring and rerifling. In the 1930's a small batch of long barrel 96's were made using new barrels fixed into existing barrel extensions. These are known as "hashmark" barrels due to the knurling done to hide the seam where the new barrel mates. I would also suspect that this knurling serves as a mechanical fastener as well similar to staking screws in place. I decided to go the hashmark route but with some modern updates to the process. The original 7.63 Mauser case head is nearly identical to 9x19 Luger meaning the bolt face need no modifications for this rechamber.

      The first step in rebarreling involves doing a majority of the work to the replacement barrel first. The blank was first roughly contoured and short chambered. Then the chamber end was turned back and threaded 1/2-28 1.070" long. This gave more than enough shank to work with for timing and headspacing. A sharp shoulder was cut to ensure even contact all the way around once timed to the barrel extension. 

      The barrel extension was held rather precariously in the 4 jaw at the chamber location so the original barrel could be parted off. In the future I would like to make a jig for this step just to ensure that everything ran true while also having a firm grip on the extension. Once the barrel was parted, the stub was bored out and threaded 1/2-28 it's entire length; there is no need for an internal shoulder here as all of the chamber face geometries will need to be recut anyways.

Headspacing and Timing

      With the extension bored and threaded, the new barrel needed to be timed and headspaced. This process is very easy with the C96 and goes rather quickly. The new barrel was threaded into the extension as tightly as possible and then the bolt was inserted. The distance between the rear of the bolt and the rear of the extension is how much needs to turned off of the new barrel; this can be measured with gauge blocks or feeler gauges depending on how big it is. Since I made my barrel shank long, I had to turn off 0.040" for the bolt to rest flush and in battery with it torqued into place. That is the timing measurement; a set of witness marks are made on the barrel and the extension so now the barrel can be removed to headspace and reliably torqued back into the same place.

      Headspacing is simple - the bolt must close on a GO gauge and cannot close on a NO-GO gauge. I do not have a reamer extension since I chamber everything on my lathe, and needed to remove the barrel several times to get it headspaced properly. If you have an extension, this can be done with the barrel torqued into the barrel extension.

      With the barrel timed and headspaced, the chamber face geometries can be recut. The extractor groove is in a very inconvenient spot, but can be cut with a long length endmill. The biggest headache was getting the angle of the cut right; approximately 30 degrees is what I came up with but this example is extremely worn. I would be interested what the angle truly is. The feed lips are milled into the underside of the extension with the feed ramp directly infront of them. The corners of the feed ramps can be cut in the same set up as the extractor groove since they share the same angle. The sharp corners left over on the chamber of the new barrel from this process were lightly filed back to get everything to feed. 

Sights and Silver Solder

      Silver solder and I have had a tumultuous relationship throughout my gunsmithing career. On some projects I've been able to execute a perfect solder joint in one shot no problem, other projects I've been baffled as to why my 8th attempt won't stick together. It's a skill that I'm "good enough" at but would like to get much better at, and practice is really the only way to do that. The front sight on the old barrel was machined off of the stub and a corresponding slot made on the new barrel. Both sides of the joint were tinned and then soldered together using wire to hold everything into place. Once everything cooled off, it was cleaned up with emery cloth.

      In the past, a rebarrel like this would've been held in place with silver solder or braze. I went a more modern route and chose Loctite 638 as the retainer. It's a high strength retaining compound that also acts as a very high strength threadlocker - a perfect mix of both worlds needed for this. The downside of using epoxies and similar for this work is not being able to  apply hot chemical finishes such as bluing or parkerizing afterwards. Get all of your finishing work done prior to using a threadlocker or similar if desired. I left mine in the white with the idea of rust bluing it later down the road.