www.MG42.us

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Due to lots of missing pics etc. I'm posting this pdf that I have of this build.
Someday might be able to replace the original pics. Anyone have any of them?
Later 42rocker ---------------------------------------------------------------------------------------------------------------------------


First before you begin there are a couple of modifications that must be done to the receiver
BEFORE you start welding it to make it legal. The gripstick area must be machined out to not
accept an unmodified full auto grip stick. Second the receiver must be modified so that a
full auto bolt will not fit in. This is done by welding in a block or stud in the rear of the receiver.

I have had my kit for several days and have been figuring out how I am going to get the
receiver welded up properly. While the kit contains all the parts for a complete gun, I do not
Think that is is a parts set from one gun, hopefully this will not matter.

I am planning on starting from the rear of the gun and working my way forward.

The first step is to grind all the cuts and remove ALL the slag and burned metal to get to a
clean solid surface. I would recomment blasting the weld areas before welding. I plan on
TIG welding it and the rule for TIG is the cleaner the better.

I made a set of plates from 1" x 1/8" and 1 1/4" x 1/8" steel to use as a guide in clamping and
locating the parts for welding. These are nothing fanct, set them inside the receiver along
the bottom and drill a few holes through the rivet holes to hold them in with #8 screws.
These will aid in the alignment and setting the length. The bottom photos show them in place.

Hope it turns out well for you. Mine that I've done turned out ok, but it's tough to get a machinist to do a small semi auto bolt job for love of money. If I owned a machine shop that would change in a hurry. I hear Huntsnmountains is very busy...hopefully my grip sticks are comming along too! Keep us updated! Slowfinger

I am a machinist, but I don't have a shop anymore, I sold it several years ago.
I am dependent on using a fieinds machinery so it is going to be a drawn out process.

Pirate, nice job, looks great..

Don't you have to use some type of non-ferrous bar stock to keep it from becoming attached to the receiver when welding? or is the required backing different than the jig or frame? Pirate, great job on detailing the process, please keep it up as it will help all of us waiting on the group buy immensely.

Slowfinger,

busy is not the word between mandatory OT and doing gun parts for guys swamped is a better word, your grips are coming along just waiting for more ar-15 trigger parts to show up. PM me when you get a chance.

GR

Now that the weld areas have been prepped and the alignment bars are made you can
test fit the sections and scribe reference marks on the bars. This will show if the sections
shifted during welding. You can see that the kerf varys in width at various places and
some areas will need more weld than others.

The next step is to modify the center section so the fa bolt and grip stick will not fit iin.
At this point I am only going to remove enough to keep the grip stick from locking in place.
I will finish the work in this area after the grip stick mods are done.

I plan on using a 3/8" stud for a bolt block, drill and countersink a hole in the area shown in
the photo. Have the recuperator installed and start with a small pilot hole, remove the
recuperator and since it is thin I would recomend using a unibit on it to finish the hole.
drill the hole in the receiver and countersink it for welding.

The next step is to determinr the bolt block height. Install the rails with #8 screws and slide
in the bolt. measure through the recuperator hole to the flat area on the bolt. Mine measured
.650" I am figuring .020 to .030 clearance for the bolt should do. you can make the pin frorm a
drill bit or dowel.

While you have the rails in check the fit of the bolt, if it is to tight the recevier will have to be spread
before welding. make a shim block to fit in the bolt groove for this.

The areas to be welded will have to be backed up with copper plate. several peices will have to be
formed to fit the contours of the receiver. as soon as I get some plate I will post photos.

After all this prep work is done I would recommend thourougly cleaning the receiver sections.
This will remove all the hardened grease and will make parkerizing easier when it is all done.
I am going to boil all the parts in a citrus based degreaser. this will get all the grease out of the nooks
and crannies of the parts.

Pirate,
Nice crisp pictures. I'm enjoying this.
Does the booster end attach in a similar way as the rear, and trunnion parts do? It
seems like bar stock is too flat to enter the sidewalls of the front end of the reciever.
Or do you have another scheme for that piece?

Karb

Karbinator, I haven't gotten that far yet! I am figuring it out as I go. My objective is to
be able to do it with a minimal amount of stuff for the average builder. I am working out the
details as I go.

Please keep these pictures comming, this is great....

This build will be posted in the MG42 FAQ under Pirates build. All the unrelated post will of course be left out.


Steve

I am currently sourcing out the various bits and peices necessary to do the bolt and gripstick.
carbide drills, drill rod, etc.
Is anyone interested in a kit of whats needed? also a set of parts to do the bolt & gripstick.

need a waffen stamp set

Pirate,

remember that their is no spring guide on these, sometimes you have to radius the F/A bolt stud or move down some to clear spring, it can be a tricky little thing. The bolt extension should also have a c-bore to seat the the recoil spring so as to elimenate movement, some I even welded the spring onto ext. to better control it during recoil.

GR

Hi Hunts,
is there any reason the stud couldnt be put further to the rear in front of the buffer or farther forward in
in front of the grip stick? as long as the fa bolt can't lock it seems it would serve it's purpose.

Pirate,

the farther back I moved it the worse it got, so I moved forward as far as I could, so if needed you could still remove recuperator. The ideal way would be a piece steel angled on both ends so the spring does not catch but then you cannot get the recupertaor out.

Hunts, how about welding a rectangular block with tapered ends to the recuperator,
then drill through for the welded stud. if you make it about 1.5 x the width of the coill
pitch it should prevent the spring catching.

Got a tig welder and supplies today, I should be ready to start assembling the receiver next week and will continue the thread.

Pirate I'll get some pics tonight of the block with the angled ends in the reciever.

GR

I machined out the grip stick slot about 5/16" longer to prevent the fa unit from locking in.
I will machine the slot to final size after the semi trigger and hammer modifications are done
to the grip stick.

The hole for the FA bolt block is drilled and heavily chamfered to weld in a 3/8" stud to
prevent a FA bolt from being used in the gun. After this stud is in place it is time to start
welding!!!