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C3a1 project
A while back I got the bug to build a C3A1 clone from one of the PH M84 single shot receivers floating around out there.
Well, that's when the search for parts started to get real interesting. At this point, all I had was the receiver in the condition you see in the photo. After many months, I was able to locate a few parts from the US, UK, and Canada. The big challenge has been the bottom metal. I was only able to find a trigger bow, mag catch, and screw. Finally, I got a big break with finding 2 magazines that were unfinished. Basically the main mag body was formed and welded, 2 spacers, and the bottom insert. No springs or followers.
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10-22-2020 11:37 PM
# ADS
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After over a year of searching, I was able to find a bolt. It took a while to find the correct bolt. Apparently one of the lugs is longer, which is different than your standard mauser-style.
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This is when my excitement melted into a warm, steaming pile of disappointment. This bolt was not finished at the factory and I soon found out why. It became clear during the machining, the firing pin hole was not in line with the center axis of the bolt. I decided to move ahead and threaded the bolt handle to accept a C3A1 syle knob. I also bushed the firing pin hole to bring it into alignment.
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While working through each challenge and researching any information I could find, it became apparent that some of these receivers may not have been heat treated sufficiently. I could tell from working on the bolt that it certainly did not have the appropriate hardness. I connected with a local metallurgical testing company and they were kind enough the help me out. Good and bad news. The receiver tested out at 43 HRC, the bolt.....a whopping 8 HRC. No problem, just send the bolt for heat treating, right? Well, for those that may not be aware, the heat treatment technicians need to know the exact composition of the alloy if you're going to have a shot at obtaining the hardness you need. You can't just call Parker Hale and ask. Once again, the metallurgical experts to the rescue! Enter the amazing world of XRF, or X-ray fluorescence spectroscopy. using XRF, they were able to determine that the bolt was 4140. Off to heat treat, and it came back 43-45 HRC!
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Bottom line, everything is off. But, after many hours of struggling, head scratching, researching, we're getting somewhere. I fully admit that the juice may not be worth the squeeze. But, the whole point of this exercise is to learn, and there is a metric **** ton of learning being done.
Come to find out that the firing pin, mainspring, cocking piece assembly is off center as well due to the misalignment of the hole in the bolt body. I fiddled with the firing pin for hours to get it to move without binding. It is something on the order of 0.050" eccentric from the base of the firing pin (where the spring stops) to the tip.
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Trued up the top and bottom of the receiver, milled in the slot for the scope base, including the dovetails near the front. Opened up the mag well. That geometry was very challenging to execute.
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Trued up the threads and face of the receiver, best I could. You can appreciate how off center everything is. Hence why machinists with vastly more experience and knowledge decided to scrap this. And here I am trying to give this thing life. Idiot!
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I received my barrel from PacNor and proceeded to thread/chamber. Worked out some pillars and completed the bedding. Even the pillars were a pain in the ***. I had to keep in mind that the rear pillar does not contact the receiver directly because the rear portion of the trigger is between them. I decided to make the rear pillar with a sacrificial portion to maintain the spacing while bedding. I then milled off the exact amount from the rear pillar for the trigger.
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Made the mag box from scratch using photos. Also fabricated the front portion of the bottom metal that secures the receiver front. The real fun was trying to make a follower from scratch. I'm using a spring from another magazine that I will secure to the follower with a rivet once parkerizing is complete.
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And this is as far as I've gotten. Next step is metal finishing, testing, adjusting, and parkerizing.
Attachment 111788
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