Removing Demilled Parts Bold are my comments, the rest is from weapons guild members
All demilled parts that can be removed are shown below
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I used an acetylene torch and some pliars to remove most parts. The end cap and front barrel support are held in by pins and the most difficult to remove. o It is best to grind down the front barrel support before you desolder it so you have a grip to hold on to while grinding it down to fit the new barrel. Pins hold on the rear channel. This channel holds on the end receiver cap. It is a huge pain to remove this part.
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Do not bother removing the j-slot end cap, it will likely get ruined. Either make a new one (mentioned below), or cut the tube it is soldered to and weld that piece onto the end of your pipe. Then use a cylinder hone to smooth out the weld (or sand paper flag mentioned in miscellaneous). Pins hold on the front nose piece in three places.
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o Attaching Parts
Most parts are attached via brazing and can be reattached using the same method. Alternatively, you can attach the parts using a bunch of small tack welds to minimize warping. o I experienced little to no warping using an acetylene torch to fully weld on all parts.
Denial Strip
The Denial Strip prevents a FA bolt from being assembled into the gun. This should be installed early on to avoid legal issues. This part is welded to the inside of the receiver. The slot on the SA bolt will allow the bolt to fully chamber. Install Denial Strip at start of build. Goes between rear of barrel and trigger sear opening. Can be a piece of bar stock. I think this can technically go anywhere as long as it prevents a FA bolt from being put in and isn’t easily removed. The rear barrel trunnion must be cut or slotted in order for barrel to be removed and inserted once denial bar and front nose piece are in place. Alternatively, you can install trunnion before installing front receiver cap. Denial bar weld holes are about as wide as the bar itself to allow weld to fill and attach to bar. o These holes are drilled in the receiver tube. Then insert the denial bar and clamp in place and weld through the holes
Barrel
Several parts make up the barrel assembly. o Complete barrel assembly
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Front reciever cap Front receiver cap and barrel nut shown
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Rear trunnion and barrel
Barrel nut (seen above) Front receiver cap attached (nose piece) I ground off the front and ground the barrel hole larger so that the threads of the barrel can fit through the opening. (not mine picture below, but similar process)
The Front receiver cap is welded to the receiver tube. For my rear trunnion, it was essentially a press fit into the receiver tube. Once finished, I welded it in place through a few holes in the hand guard. The trunnions job is to keep the barrel supported in the tube and keep it concentric. It also takes the impact of the bolt in my setup, and was welded in place. Once the barrel is in place and protruding through the front receiver support, a barrel nut is installed to keep the barrel stabilized. I threaded a set screw through the trunnion that pushes against the barrel to keep it from rotating.
I also put a set screw on the barrel nut to keep it from rotating loose during shooting (which was a problem I experienced).
It is best to make sure the barrel is spaced correctly before welding in the front cap and rear trunnion. I welded my front cap in too far forward and had to space the barrel back using cut down washers. Need barrel nut
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http://www.brownells.com/aspx/search/skudetailv2.aspx?sid=102227&pid=45298&tabi d=0# Original is 1.185" OD. 5/8”X24 tap If they are out, they have others available, just search. Barrel chamber o There should be no gap between the breach and the bolt. I have my bolt setup so that it will impact the face of the trunnion, and hence why it should be welded in place. o When putting it back together, leave the firing pin out and cycle a few rounds through and pull back as far as possible. If the rounds extract with no problem and don’t look crumpled, everything should be good. o NOTE: The APEX barrels may come short chambered and will need to be reamed to the proper size. News is that they are adding extra controls to prevent this from happening again.
Magazine Well
I inserted the magazine and ejector rod into the magazine well to align it with the tube. I then tack welded the magazine well in place. Then removed the two and finished the weld. Be careful about where you tack weld as it can melt the magazine a bit. “From the front of the magwell opening in the tube to the breechface/trunnion is 0.100" on the factory Mk6. It's 0.197" on the WLA copy we have.” o http://www.weaponsguild.com/forum/index.php?topic=25415.45
Springs I originally had the gun together with the original long/wide spring and a short skinny spring made from McMaster part # 9663K92 (17.5 coils, the top & bottom squared and ground). I sized the firing pin spring so that, with the springs in place, the bolt would advance forward if you were to let go of the bolt anywhere along its cycle. When I went to fire the gun, I got about 70% light strikes on the primers (failure to fire) and 30% fired without issues. So I debated going for more coils on the 9663K92 spring, but noticed it was basically collapsing in the tube instead of compressing evenly. I then decided I was going to make the long/wide spring stiffer and ordered some springs from McMaster. I ordered: 9663K99 and 9637K18.
The 9637K18 are too big in the ID and go past the coupler (joint between large and small spring), so I just put it in without the other springs. With a stronger firing pin spring, it had no issues pushing the
whole bolt forward plus some. I reduced the ID at one end to fit the spring guide face and keep the spring centered. I haven't tinkered with the 9663K99 spring yet, but the ID does fit onto the coupler (although a little large still). If you want to still have two springs, this may be a good choice for replacement. With the single 9637K18 spring, the gun fires perfectly. Stock
I welded the stock location after aligning the stock locking mechanism with the rear cap. I then folded the stock under and cut the front latching square after it was welded. This ensured proper seating and locking of both parts. The back cap J slots should be remade. I bought from onlinemetals.com ( 4130 - ALLOY TUBE ROUND, 1.625" OD X 0.058" WALL NORMALIZED ALLOY STEEL TUBE) o This is the perfect size for these caps. o It is really easy to make with a dremel and easy to fit to your end cap as well with little to no effort since you can see where it is binding.
Miscellaneous
Used Stenparts.com for receiver tube. Rear site and stock latch are in wrong place I believe. After drilling holes, you can attach a piece of sand paper to a dowel (like a flag) and spin inside the tube to debur. Cut dovetail for site using triangular file. Bought SA bolt, SA trigger, SA firing pin, SA Spring guide from Apex. Modify the Full Auto (FA) charging handle using a grinder for use in the Semi Auto (SA) bolt. o Be sure you grind it down enough or the bolt will seize in the receiver tube when you attempt to pull it backwards. Bolt assembly can be seen below.
Pictures of the Build Sequence Parts kit arrived:
My Machine shop:
Cooling Holes Finished:
J-slots made:
Before paint (parkerized):
Finished Product:
