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blackreichswehr wrote:sorry, my former post, wasn't helpful. get yourself some layout blue and a metal scribe. make your cuts on the inside of the line, use squares for all your layouts. did you measure each side of the receiver shells? one side or the other, maybe both-- may need some milling, be advised of your O.D.

Yea my dremmel kinda jumped on me like a lot,but yes i am getting through alot of it quickly, i dont really have anything else in my spare time to do so its all i do outside of work. Though the cuts are ugly and chewed up everything fits and seems to work, i just finished squaring and cutting the shroud for the mg3 repair section from rtg fits like a glove im still filing and grinding occasionally the point where the rear receiver meets the front shroud i know the measurements given to me from the first dimple on the receiver to the rear of the camm hole ia 28mm im still a few mm long but im taking it slow on this one, haven't messed with the rails yet but hopping to get them lined up and installed before i have it welded.

Honestly to me it doesnt look so bad though im no machinist i pride myself on being able to do most anything with hand tools (within reason) alot of the marks your seeing though from my cuts are just a runaway dremmel it scratched the hell out the the area around the cutouts but its all cosmetic, its a garage build so as long as it functions im ok with it basically gunna bead blast it after all said and done the use header paint or possibly dura coat haven't decided yet.

I could use some measurements from the rear of the camming window to the rear of the receiver though if anyone has that, looked around and cant find it

Just a mock up, its comming along

So i got it all put together i drilled the holes fir the rails and cutout the D holes for the rails. Seems as though i hace miss alighned the right(charging handle side) rail though it is slightly below the camming block so trying to revisit this issue and correct it open ti helpful suggestions as the drill bits kep walking towards the old holes even when i clamo the rail. Other then thst its all ready ti be welded witch will happen hopefully in the next two weeks

Trayce1911 wrote:Honestly to me it doesnt look so bad though im no machinist i pride myself on being able to do most anything with hand tools (within reason) alot of the marks your seeing though from my cuts are just a runaway dremmel it scratched the hell out the the area around the cutouts but its all cosmetic, its a garage build so as long as it functions im ok with it basically gunna bead blast it after all said and done the use header paint or possibly dura coat haven't decided yet.

I could use some measurements from the rear of the camming window to the rear of the receiver though if anyone has that, looked around and cant find it

Measurement from rear of camming window to rear of receiver is 382mm can be short by .2mm.

I've built some that ended up 383mm (over compensated for weld shrinkage) and they work fine.

Trayce1911 wrote:So i got it all put together i drilled the holes fir the rails and cutout the D holes for the rails. Seems as though i hace miss alighned the right(charging handle side) rail though it is slightly below the camming block so trying to revisit this issue and correct it open ti helpful suggestions as the drill bits kep walking towards the old holes even when i clamo the rail. Other then thst its all ready ti be welded witch will happen hopefully in the next two weeks

What are you using to drill your holes? if you are using a drill press try clamping the receiver down and drilling it with a center drill. Only problem you will still have is when you rivet the rails in the rivets will pull the rail in the direction of the old holes. You could weld the rails through the holes however I don't recommend it because it would make any future repairs difficult. You may also be able to make a spacer to hold the rails in place as you rivet but I have never tried it so I can't say it will work. Last idea is to weld up the old holes. To do it as cleanly as possible clamp a pice of bronze(brass may also work) flat to the inside of the holes and fill the holes with weld, preferably tig if you have the option. The weld will puddle ontop the bronze and if you do it right it will make the inside relatively smooth.

Der Alder wrote:I've built some that ended up 383mm (over compensated for weld shrinkage) and they work fine.

Mine ended up about 1/4 in. short and functions flawlessly. Was having issues until I changed to good ammo. Shorter will likely only require less gas presser to operate, not that one should stray from proven blueprints.

Sw1ngK1ng wrote:[
Mine ended up about 1/4 in. short and functions flawlessly. Was having issues until I changed to good ammo. Shorter will likely only require less gas presser to operate, not that one should stray from proven blueprints.

Only bad 8mm ammo out there is 80s Yugo brass?

[/quote]What are you using to drill your holes? if you are using a drill press try clamping the receiver down and drilling it with a center drill. Only problem you will still have is when you rivet the rails in the rivets will pull the rail in the direction of the old holes. You could weld the rails through the holes however I don't recommend it because it would make any future repairs difficult. You may also be able to make a spacer to hold the rails in place as you rivet but I have never tried it so I can't say it will work. Last idea is to weld up the old holes. To do it as cleanly as possible clamp a pice of bronze(brass may also work) flat to the inside of the holes and fill the holes with weld, preferably tig if you have the option. The weld will puddle ontop the bronze and if you do it right it will make the inside relatively smooth.[/quote]


I was using a hand drill its what i got... but ive decided im just gunna spot weld them in place through the already drilled holes. They line up just fine just did a mick up and slid the bilt through em freely a few times i figure if i ever hace to remove them ill jus drill put the spot welds on my holes. At this point im just waiting on my welder to get some free time. Need an mg3 buffer and a semi bolt or conversion parts and ill be ready for test fire.

Currently all welded up however when i installed the recuperator the grip stick did not fit anymore the tube appears to be overhanging that area slightly may make a few more alterations to the extra materal on the tube, also having a bolt binding issue when i mount the rails it will glide smoothly untill i get to the camming block then will go no further it feels like its binding somewhere just can see how my rails may not be high enough as they are directly in line currently i figure ill have to remove some material from the tops amd possibly bottom of the rails to raise them ass needed but again not sure this will solve the issue still trouble shooting

Trayce1911 wrote:also having a bolt binding issue when i mount the rails it will glide smoothly untill i get to the camming block then will go no further it feels like its binding somewhere just can see how my rails may not be high enough as they are directly in line currently i figure ill have to remove some material from the tops amd possibly bottom of the rails to raise them ass needed but again not sure this will solve the issue still trouble shooting

can you upload a couple pics of where your rails join the camping block?

Pretty sure i got it sorted out now, seems to glide smoothly now i figure im gunna end up welding them in place as well. Dont have any pics of the bolt or rails lined up right now but ill get some there pretty in line though. I figure ill use the bolt as a jig of sorts and spot weld my rails in place and adjust it down the line as i got and keep checking how it moves as i go

Just be carful with the alinement. That alinement is what causes out of battery detonations when its not right. A good way to make sure the bolt runs smooth it to run it through the rails and unlocking piece by hand and if you don't feel any ledges that it has to bump over then it should be ok, it won't tell you if your rails are twisted though. Your rails are probably the most crucial part of the build.

Trayce1911 wrote:Here are some pics

Awesome thread.. now are these markings on the receiver based on the BPR dimensions on their PDF?
I am starting my build... and starting the cuts is the first scary part lol!

Trayce1911 wrote:Ok i made the first cut got the cammin block on but ran out of dremmel discs so cant get the other side on yet. But based on thus point i started marking the receiver based on the srawings i got from gunbroker.

To answer your question i dont have any prior machinists skills just kinda floating through this, hence why im gathering all the information i can, i have a gunsmith local im good friends with but he made it clear he wants nothing to do with this build

What plans where you using that you got on Gunbroker. I am actually trying to figure out where to cutout the square holes where the camming arms go into. Thanks in advance.

So I'm not sure if this is related, but I had to trim my recuperator quite a bit for the brp gripstick to fit. I would reccomend doing it by fit check, meaning physically see where the gripstick hits the recuperator ledge (which is to the side of the tube). You should only have to take out little amounts of the ledge for the gripstick to clear the recuperator ledge. Once your done you should have a rectangular cutout, where your gripstick front twists into the gripstick cutout. I had to take my recuperator in and out of my receiver atleast twenty or so times to get it just right. Its painstainkly tedious but the recuperator is almost like the heart of the receiver, because it connects or aligns to mostly everything in some way. I followed the brp specs for the gripstick cutout but still phsically checked it, and of course take out as little material as possible. I used a scribe, my square and ruler, a dremel with a cutoff wheel to cutout some of the material and grind away others. I would've used my tungsten grinder but its too aggressive and you have to watch to not cut that tube, like really be careful D:

How is your build going? Im thinking about doing another when I get my tax return.

I am redoing my original BRP build steps as a PDF file that has much clearer drawings, new drawings, and gets rid of alot of confusion. Not sure if I can post a PDF file to this web site thou. Should be done around the end of Feb. It should definitly help you out.

If it won't post here, I'll upload it to an open directory on my Germanmanuals website and put a link to it here. I don't have upload size limitations on Germanmanuals.com, so not a problem.