Last Post: 06/29/2008
Retrieved: 01/21/2011
Finally ready to test fire. I have not drilled out the gas port yet. I'm going to test fire and enlarge the gas port one size at a time until she functions, if necessary. I've got a good 45 hours in this one with another 20-25 hours of mental planning and sleepless nights. It was worth it as the cool factor on this one is off the charts...
I used the original top cover spring. I just clipped one leg and reshaped it slightly.
I used a double spring setup. I had to slightly taper the sides of the hammer to clear the springs. It pops primers 100% of the time.
I still have to clean up the welds and Duracoat after I get running trouble free.
Dvann -
Nice job. I know it took a lot of work! I like your simplified idea on the pressure-plate spring mod, and how you designed your BC extension. Hope test fire goes well; anxious to hear your report. I envy your twin-spring system.
The more builders that tackle the MG47, the easier and simpler the design will become. Dvann, you've proved there are a lot of shortcuts and improvements still to be developed.
I fooled around in the shop some tonight testfiring in my snail drum one round at a time. Looks like somewhere around .190 is going to be the gas port size. I made another close tolerance gas tube and installed a regular gas piston. I'm going to take to the range tomorrow. I hope I have the correct combo dialed in. I'm scared to shoot it tonight in the snail drum cause if it doesn't work I'll be in the shop all night. I just can;t seem to put a project that's giving me trouble down. I KNOW THAT I'M THE ONLY ONE WITH THAT PROBLEM.
I took the MG47 to the range today. I got it to function several 5 or 6 shot strings. I think that since I used a 16" Romy barrel that I'm going to install a Krink style booster to lengthen the gas pressure curve. BUT IT DOES WORK.
MG47 prototype and MG47ES prototype to work but it is defiantly do-able if you keep at it. I tried a Krinkov booster but had more luck with opening up the gas port to about .19" dia. than with the booster to raise the gas pressure on the gas piston to get reliable functioning. I like your clipped spring on the pressure plate solution. I think I am going to try that on my MG47 and MG47ES.
To all that are considering building a MG47, I have nearly got the drawings done for the MG47ES receiver, guide rails, BC modification, BC extension, gas piston modification, gas tube modification, gas block modification, FCG tray, grip stick and a general assembly done and ready to publish. I need to make a drawing of the feed tray modification and front trunnion modification. The MG47ES does not require a lathe, milling machine or a welder to make. It is interchangeable between a grip stick or a spade grip. I used a RPK kit for it but you can use a Romy AK kit as a bases also. Watch GUNCO.net under the MG47 and MG47ES thread for more detailed info on these builds and the status of the drawings.
Thanks Sharpsshooter. If you look at the pic of the clipped spring you will notice that I also Dremeled a small notch in the pressure plate where the spring leg contacts it. This further relieves some tension. I have my gas port at .191 now. I built a booster last night to increase the impulse time and will test fire this afternoon.
The short stroke problem seems to be cured by the booster I fabricated. It has an inverted cone which slows down the gas exit. I can tell from the increased recoil that the springs are being fully compressed. The bolt speed has also increased which created an ejection problem. All malfunctions that I experienced today were from an empty not clearing the ejection port. I came home and moved the ejector forward about 3/8 inch and installed a new extractor and spring (thanks trailrider). This drastically changed the ejection angle. Next range trip will be 8 to 10 days out. Everything we do to these MGs affects something else. The trick in finding the right combination. Gettin' closer to perfection.
CETME/G3 pistol grip is usually right in front of the stock(?)
Length of pull is around 16". Remember that belt feds are designed to be fired from a bipod. The placement of the rear of the bolt determines where you have to mount the FCG. An MG42 stock would shorten the LOP but I wanted to go with the G3 stock. All of the current working MG47s have a fairly long LOP due the the design of the receiver. Just the nature of the beast.
