I like where you are going with the extended tail on the BC to carry the TC actuator. I wonder if you will see flexing and cracking in the weld joints due to the stress in the arms extending back from the BC. You are definetly cutting edge. Nice work!
How long is the extension back from the original bolt carrier to support the TC actuator? I assume it would vary depending on where you locate the feed tray and hinge point for the RPD tray and TC.
Got mine feeding, hand-cycling smoothly, but had to go with RPD "U" links, after re-locating the feed stud 3 times. Stud's located 5/8" behind the inside rear of the tray, to account for the aft tray location. DM1's are spaced too wide for the RPD TC to push them into the slot.
Have some rcvr flex (wall = 1/16") so am planning a curved bridge behind the tray. Good thing the BC ext has direct contact with the upper rails, or flex combined w/ BC slop would be worse. Not much clearance in there for a bridge. I went with both rails full length, so that helps w/ rigidity. Thicker left rail would have been even better (2XTM's has a VERY thick left rail). BC slop will diminish when the full-length welds are done, due to contraction / hourglass-like effect even with spacer & clamps. I can see alot of filing heading my way.......
This may wind up as a carbine experiment instead of a pistol, using the short gas system. My first RPD TC attempt, DM1 links (unsuccessful), short gas system, plus the twin-spring system is a vertical learning curve. Too many variables to tackle at once. RPD links are TIGHT compared to DM1's. Recoil springs & SMOOTH CYCLING will be the trick
Pirate - Thanks for sharing your pics - looking good - keep'em coming
Last edited by cntrailrider; 03-09-2008 at 07:56 AM. Reason: You can see I'm a nocturnal builder - NO DISTRACTIONS. Just a steady focused hummmmm You graveyard workers know what I mean
looks like things are coming along
I've decided to go with a stock, for now, to simply things, but that also means a longer front end. Today I worked on a recoil spring guide tube, mounted in a G3 stock. The cuts align it solidly in the upper rails
The tube has since been welded in the front; plugged pinned & welded at the back end, and trimmed to (temporary) length inside. Tube extends back to the buttpad. The BC extension will travel INSIDE the sq tubing/mount to gain extra stroke length. First I need to weld the guide tube in the BACK of the stock attachment (sq tube) and drill take-down pin holes while it's still 4-sided. Then remove the front 'panel' so the tube is hollow, so the BC ext can travel almost (buffer) to the TD pins. Rvcr is presently 14" so everything's compacted. Then add epoxy filler to the stock-rcvr joint (spray oil inside first, so it can be removed later) and sand with a flapper disc, for a seamless fit. At least that's the plan. Mice & Men, right?
Welded most of the full length seams on both sides of the rcvr, without contraction or warpage. Still cycles smooth and I am thankful. That's where I ran into alot of problems building the MG47 - hand-filed till I wondered if there'd be any rails left. Very tight in there too. I had cuts-on-top-of-cuts OUCH!
PS I FOUND a LONG barrel extension - that'll save alot of work, and will get to see if the short gas system works, in spite of things
Last edited by cntrailrider; 03-10-2008 at 05:02 PM.
i like cnt's idea and am trying to do something simular. i am using the rear section of a fal lower. i left out the internal spring, but installed the tube. i plan on adding a bracket on the top like the one on the bottom to stablize it. i will drill it out to allow the spring to enter the stock tube. this is a very ruff idea and i will modify and clean it up later. the brackets will be tig welded to the rear section of the fal part. i have drilled and tapped the bracket to be able to bolt it to the receiver. this is my first attempt at this and a lot more work is needed on it, but it is a start.
i think i am going to be able to use the fal rear sites also.so far they will line up.
Last edited by sgt ron; 03-10-2008 at 09:02 PM.
What is strength and length of your springs? Where did you obtain them?
M60 from SARCO. START at around 16"+. It's in "The BIG Thread"
Here's my newly designed 'Ferrari' BC extension. The diagonal is to clear the top TD pin, for a longer stroke. At the rear of the stroke, it's between the pins
It's a VERY TIGHT fit between the hammer arc and the BC ext, beneath the feed stud. The hammer does not extend to the top of the bolt (more pics later) and that is with the "L" portion bent up slightly, for clearance
It cycles the BC ext clear into the stock mount. Total stroke is 5.25", and the face of the bolt can travel 1" behind the feed tray. Made a comfortable cocking handle from a scrap section of barrel, but a vertical handle (like an MG42) would protrude less. A folding handle like on an HK, would be the ticket
Tomorrow I sand the epoxy flush, and we'll see how she fits. It looks like the 'plan' worked out well
Steve in El Paso
PS A guy over at Subguns posted 'this would be an easy build'. I hope he shares his amazing shortcuts!
Last edited by cntrailrider; 03-14-2008 at 12:58 PM. Reason: Sober now
Nice and Nice, I know who I'll be bothering later on.