My Build, step by step

[Pirate]

How about cutting a piece out of some scrap ratchet plate to replace the missing area? Just weld it in and clean up.


Steve

Thats my plan in a nutshell!! I got a section from a scrap bpr receiver section.
You did a great job on my build post, looks EXCELLENT!!!!!

[Pirate]

I ordered rivets today, if anyone needs some PM me as I goy WAY more than I need.

[Karbinator]

Were the reciever holes for your rivets ok? I got a reciever that had one side drill pressed completely out to the
Bit size, and I'm scratchin my head on how to fill that without making the rivet, or rail for that matter, completely permanant.
Mine is a 3 cut as well, and have been told some are, and some are not like this.
Anyone else seen this? looks like a real Bitch to get alignment to the cam piece, and buffer. Hmmm.....what to do?

Karb in Va.

[Pirate]

Karbinator, I am not sure what you mean, did they drill the holes the size of the rivet head? if so weld them shut and redrill to proper size. If the holes are only slightly larger use a longer rivet and it will fill the void when properly crushed. I have some longer rivets coming as my holes are slightly larger.

[Daskraut]

Guys, do me a favor, please buy a 1/4"hand grinder (90degree head) and some 60 grit , 2" flat sanding disks to clean up those welds!, it looks like you are using a body grinder from an auto shop and you are going too deep!. Also, the jig is for tacking only , right?. I know if you weld with that jig out of sequence, that receiver will warp. Just my 2 cents.

[Karbinator]

Karbinator, I am not sure what you mean, did they drill the holes the size of the rivet head? if so weld them shut and redrill to proper size. If the holes are only slightly larger use a longer rivet and it will fill the void when properly crushed. I have some longer rivets coming as my holes are slightly larger.

Pirate... Good idea, but it's going to take weld for mine. The De-mil guy drilled the hole all the way out to the outer opening. I can
almost stick a small pencil through it. I guess I could get some Copper rivets in the rails....align and clamp...weld shut the holes...knock the rivets out, and install regular ones.

thanks for the input

[Pirate]

Guys, do me a favor, please buy a 1/4"hand grinder (90degree head) and some 60 grit , 2" flat sanding disks to clean up those welds!, it looks like you are using a body grinder from an auto shop and you are going too deep!. Also, the jig is for tacking only , right?. I know if you weld with that jig out of sequence, that receiver will warp. Just my 2 cents.

The welds are rough ground at this point, I will use a finer grit when it is time to do final finishing. the receiver will be abrasive blasted to give an even finish before parkerizing.
Yes the jig is to align and tack the sections, if properly welded it will not warp.
What kind of jig do you use for welding yours? Did yours warp?

[Daskraut]

the best way to keep it from warping is to clamp/attach it to a thick steel table. You can almost watch the thing warp if you get too much heat in all at once.Just try and clamp it on the inside so as not to crush the receiver! ,these suckers are soft and flimsy!. What I was saying about the sanding disks is even though you are not finishing the welds yet, it is alot harder to remove too much material with these. Every weld/area you have to fill will increase your chance of warping the receiver again.

[Pirate]

Based on my experience no amount of clamping will prevent warping or shrinkage of the welds.
The way to avoid this is to tack the parts together so they are properly aligned and fill small
areas on opposite sides so the shrinkage is even. close the gap with several passes from both
sides then connect the parts. Since the receiver is curved and tapered it would be very difficult
to clamp it and have it come out straight.
Weld is hot when applied and shrinks as it cools, no amount of clamping will change that. It is
also important to not put to much heat into the parts before they are securely tacked, as this
will cause misalignment. It is important to understand that the sections cannot be welded
all at once , but in small sections.

[Pirate]

I cut a section from a scrap section of ratchet plate, it was not the correct section so I had
to cut the slot. I beveled the edges and welded it in. I also built up the slot on the bottom,
I plan on using a mill to finish this.

[Pirate]

At this point the major reconstruction process is complete. The next step will be to install
the rails and test fit all the components. I am planning on using a friends mill and rivet tools
this week end to make a bucking tool, install the rails, finish mill the slot for the grip stick,
and possibly make some of the bolt parts.
I plan on making the bucking tool from a 7/16" coupling nut and bolt, I will post pictures of it.
At this point I will start on the gripstick next to get the shape of the slot to be milled into the
receiver. I am planning to try to salvage the front of the gripstick to use the origonal
attachment ears. If this doesn't work I will use angle iron for the attachment.

[Pirate]

I got to use a friends lathe and mill today, I machined the slot for the buffer latch as I wanted it to
fit the latch lever properly. I made the bucking tools from 2 7/16" coupling nuts and bolts. The nuts
were shortened and the bottom was turned to rotate in the rails. Both bolts were dimpled for the
rivet heads and one was slotted to clear the small bar in the rails. I used a pneumatic rivet gun
and the setup worked good. A little more grinding and smoothing of the welds and the receiver
will be complete.

[Pirate]

Now I am readty to do the semi mods to the bolt & gripstick. I am planning on using the
origonal mounting for the ejection dust cover, so I milled the side plates to sit flush with
the receiver. By widening the slot for the dust cover pin and reshaping the pin it should
work similar to the origonal.
The first step is to determine the hole location for the trigger and hammer pins, I did this
by laying the parts with the hammer cocked and made a test lock. Once I determined the
holes were ok I made the side plates. The sides of the gripstick need to be cut out for
clearance and the trugger needs to be place forward enough to allow the trigger spring to
rest on the front of the grip stick. The hammer and disconnector need some reshaping to
work properly and to allow the hammer maximum travel. A trigger stop is also a good idea
to prevent trigger slap.

[gearlogo]

Hi Pirate,

What setting are you useing on the HF tig box. Do you vary? If so how do you do it. I trying to see how to do it without a foot bedal.
Thanks

[Pirate]

The welder is set at about 3.5 on a scale of 10. A foot pedal is nice but not necessary,
I had a miller with no foot pedal for years. Once you start welding you can determine if the
arc is to cold or to hot and move the dial as needed. Remember, ,this unit costs $200.00!!

[gearlogo]

Thanks pirate, I have the same machine and was wondering. My untrained self would have set it much higher than that.

[Pirate]

Here are a few usefull links for needed supplies,

carbidedepot.com
carbide drills for drilling the bolt, low prices, fast shipping.

onlinemetals.com
small quantities of metal at reasonable prices, dom tubing for the bolt extension, flats for
the gripstick plates and drill rod for firing pins.

del-ton.com
AR 15 parts

[Pirate]

Here is a photo of the gripstick with the angle iron retainer installed and the hammer ground to
clear the bolt. I still need to figure out a safety. I am not totally satisfied with this gripstick and
will more than likely do another with some changes. At this point I want to finish the bolt
and assemble the gun to get all the parts fitted and working. After I test fire it I will tear it down,
finish grind all the welds and blast and parkerize it. But I want to see it work first.

[Pirate]

Modifying the bolt.
the sear and cocking lugs must be ground off to clear the bolt block stud installed in the
receiver. The feed stud will need to be drilled for the firing pin to pass through so it must
be welded in place to prevent rotation. A lug must be welded on to catch the charging
handle and the locking wedge must be drilled for the new firing pin.
I will be using 3/16" drill rod for the firing pin, and will drill 3/16" holes in the wedge and
stud. I will take a few thousanths off the pin for clearance as the carbide drill is
exactly 3/16".
After studying the anti bounce assembly I don't think that using just the spring will have any
usefull effect on lockup. The anti bounce assembly works like a slide hammer and without
the complete assembly it won't do much. I beleive that the mg 42 works similar to a browning
design and fires before the recoil group is fully forward, and at rest. The gun fires while the
recoil group still has some forward inertia and reduces stress on the components.
Since the gun will be fired from a closed bolt with the recoil assy at rest the anti bounce
assy won't do anything.
The bolt extensions were made from DOM steel tubing. One end has a counterbore to hold the
recoil spring and the other a step to center it on the bolt.

[Pirate]

This is the bolt locking wedge drilled for the firing pin