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Help with Build

Ask your build questions here. Welding, assembly, etc.
Trayce1911
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Help with Build

Postby Trayce1911 » Wed Mar 01, 2017 11:42 am

So i got myself an M53 kit from Apex and i have about an inch of receiver left left after installing the camm block(trunnion) its all jagged as it should be and im unsure uf i should cut it square or not, so far my options for a receiver are what look to be somthing similar to brp stampings but they are not the dimples for the charging slot are there but thats it. Then theres the cold steel as the second option. Basically what i need help with are the dimensions of the rear receiver, exact but lenth for the channels for the bolt blocker, grip stick, ejection port and charging handle, basically the whole milling specs for the rear section, my tools consist of a dremel, hand files, hand drill, tape measure, and a set of digital calipers. Just nit sure where to start. The cold steel seems to be a little more machined and EASIER?? And he says he will include a schematic with it but id like some details from all of you in case i dont get that

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Re: Help with Build

Postby jbaum » Wed Mar 01, 2017 3:58 pm

Before you start getting replies, go to the Stickies section and start reading. It will answer most of your questions, and bring you up to speed on what is involved in building a semi 42.

Welcome to the crowd. :)
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Trayce1911
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Re: Help with Build

Postby Trayce1911 » Wed Mar 01, 2017 5:32 pm

Thanks, ive actually been reading here for the better part of a year, and just recently made an account i have all the details i ned besides exact measurements for the grip stick slot, ejection slot, and top feed cover slot

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Re: Help with Build

Postby blackreichswehr » Sat Mar 04, 2017 9:38 am

what type of grip handle set up you plan on using will come into play, be aware of this.

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Re: Help with Build

Postby Der Alder » Sat Mar 04, 2017 6:03 pm

I like using the Global Machining receiver shells - can be had for about $275. I use the BRP grip and bolt kit..for first time builders its best not to reinvent the wheel.

Like John said read the stickies, read the build threads here and buy a set of manuals so you understand how it works. You want the translated FA manuals because they are so detailed, but also download the the free online BRP semi manual so you understand the changes done in semi.

Once you get rolling we can get into specifics.

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Re: Help with Build

Postby Trayce1911 » Mon Mar 06, 2017 11:25 am

I actually ended up finding the templates i was looking for on weaponsguild, im planning.on using a BRP AR15 style trigger group pretty much im ready to start the buld just goimg back and forth on what receiver blank to use. Im leaning towards cold steel but still not sure since alot of the stickies section photos are gone. And i keep hearing about the "Global Machining receiver shells" but every link i try to use is bad. I went to the website via google and i only saw the uzi parts on the site, should i email him?

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Re: Help with Build

Postby Der Alder » Mon Mar 06, 2017 6:37 pm

Go the the Weapons guild site and join it...there you will find in the 'vendors section' - "Global Machining" you can get the contact info phone # for ordering there (they are great guys to deal with). If you are a member there you get like a $50 discount for being a WG member. These are the same shell stampings the Wiselite M53's were build on for years before they became milled.

They come in two lengths - standard length and extended (WL used a longer receiver).

I've used these GM shells on several builds and they are very good quality. I bought two sets recently for some upcoming builds and on my last order they were out of the standard length so I got an extended length - you may have to as well. Don't let this worry you as all the added length (1/2") in in the rear most area and can easily be trimmed off if needed.

Myself I take a big short cut and cut the whole rear buffer area off and splice on a German MG3 rear anyway. Some folks don't take this shortcut and weld/rivet in the buffer tabs and make the cuts instead. Both ways work...its whatever you choose.

Here is a pic I just took of the two set showing the difference in length.
Image

Hope this helps get you rolling.

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Re: Help with Build

Postby Trayce1911 » Tue Mar 07, 2017 8:05 am

Thanks a lot! I just got a teply from him, i currently am a member of weaponsguild through another name, im just honestly new to researching all of this ive build a few aks, and stens but this one i needed a bit of help been researching the build for the better part of a year and a half. Ill probably go with global machining since ive heard alot of good things thanks alot guys, ill keep this thread updated with progress as i go

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Re: Help with Build

Postby Der Alder » Tue Mar 07, 2017 2:48 pm

I'm glad I could help. I wish RTG, BRP and GM all had a vendor presence here as I'm sure we are their best customers.

I sometimes hesitate to direct members to others sites, but sometimes we have to in order to share info, especially on parts deals. WG is a very good site, and just like here we have a wealth of info if you are willing to dig through the hundreds of pages here. During my first build I spent many evenings just reading through old posts/pages here which taught me a lot

I'm a member of both excellent sites BTW, but for this platform, this site is still my favorite. Again, be sure to get some of John's translated manuals if you don't already have them, they are high quality and written by those who designed this gun. Reading them will help you make sense of how it all works and give you the right terminology....which is important so we know what you are referring to so far as parts.

Once you get building please come back and we'll help you along.

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Re: Help with Build

Postby Trayce1911 » Wed Mar 08, 2017 7:45 am

So i got in my newly manufactured mg42 barrel in (7.62) it came with a barrel extension attached, but it is verry tight when i lay it in the shroud with the cramming block on, i haven't repaired the front bushing yet. My 8mm barrel is very loose and moves freely should i be concerned? It will move if i stick my thumbs in the camming area and push on the extension and lock back in if i push it back.

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Re: Help with Build

Postby jbaum » Wed Mar 08, 2017 10:49 am

It needs to move freely, but it would be best to wait until the receiver was finished before you started messing with it.
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Re: Help with Build

Postby Der Alder » Wed Mar 08, 2017 3:50 pm

Like John said, I'd wait till the receiver was done before doing anything with it in that regard.

Sometimes "flipping" the barrel/extension can help due to slight warpage in either the barrel or the shroud. I've found too that some extensions (the post war 7.62 types) can sometime be a tad tighter than the German WWII extensions. Most likely the variation is either due to slight warpage or the extension itself is just a couple of thousands wider than others...at least that is what I've found in my samples. My loosest 7.62 barrels have German WWII marked extensions...many were reused post war which is why you sometimes see a German WWII marked extension on a 7.62 barrel.

Its ideal if the barrel glides freely with just gravity, but a bit of drag can be overcome by a good recuperater and enough gas (nozzle). Oil can help too.

One thing I should mention is, IMO you do not want to grind either the extension or camming pieces as they are hardened steel (very hard) and doing so puts small scratches in them which can cause fault breakage (sort of like how a glass cutter works).

With a bit of gas adjustment (if needed later) it will probably break in and loosen up once you start shooting it. This too is assuming your newly made barrel is of proper dia and is not binding on the door and other contact areas.

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Re: Help with Build

Postby Trayce1911 » Tue Mar 21, 2017 12:52 pm

Ok so i got my mg1 top cover and feed tray from Robertrtg and a mg3 front section to repair my shroud. And i just got my receiver drawings in the mail today vane with alot of pictures of a fully assembled receiver from all angles very nice drawings with measurements on everything, now just waiting to have the money for a global machine receiver then ill be getting her going. Probably gunna end up using a mg3 rear buffer tab section just for the ease of it plus i like the original stamping marks. Also gunna go for the garage build style with bolted in rails, camming section and that wedge piece that holds the grip stick in place (cant remember what its called.

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Re: Help with Build

Postby Trayce1911 » Sat Mar 25, 2017 1:28 pm

Almost ready to start the build just got my receiver shells in the mail from global machine now waiting on the mg3 rear buffer section and the brp gripstick, anyone got suggestions on where to start i dont have immediate access to a welder so that will have to wait, but i wasnt sure if i should weld then cut the channels out or not advice?

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Re: Help with Build

Postby jbaum » Sat Mar 25, 2017 2:47 pm

Welding the complete receiver together before you cut out the grip hole is called making a machinegun receiver without a license. It is suggested that you fit the grip stick before you fully assemble the receiver. Maybe assemble the back half, fit the grip (cut out the hole to size, and the full auto grip won't stay in anymore). Then add the barrel shroud to the receiver.
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Re: Help with Build

Postby Trayce1911 » Sat Mar 25, 2017 3:46 pm

Yea i knew all that i was planning on making a rough cutout for the gripstick and bolt blocker then welding the entire thing, ive read that fitting the charging handle prior to welding can be alot easier as well, i kean ive basically got eveerything i need just "hesitant" i dont wanna mess it up

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Re: Help with Build

Postby Sw1ngK1ng » Sun Mar 26, 2017 12:22 am

I made a nice jig for welding mine up. I used a block of steel that I machined to fit snug in the rails. Both ends of the block were bored to except a 1in rod on one end and the buffer spring in the other. The 1in rod extended to the front bushing and had a sleeve that fit snug between the rod and bushing. The back of the block being bored for the buffer spring helped a lot in keeping it strait with the rails. Im sure there are better ideas for jigs out there but the more ideas the better.

A few things I messed up or did differently:

I accidentally welded the barrel bushing is a half rotation out of place and had to cut it off and reeled it so triple check that before welding. The cutout one the inside dose on the side that the barrel comes out.

I cut my charging handle hole too far forward and had issues with it falling out when racking the bolt so only cut as far forward as needed. If you do cut too much I welded a short extension to the end of mine to make it stay in.

When welding in my grip mount I welded it to where the grip wanted to sit with the cuts in the receiver, not where it has to sit with the recuperator which was an issue. If I build another I would drill the hole for the front recuperator lug after welding the receiver together then installing it so I can weld the grip mount in the right place. My fix was grinding a small amount off the back of the recuperator with was kinda scary.

The BRP grip is tough to work with because the trigger group is mounted too high and I had to grind too much off the hammer so I made my own. I used the diagram on their site and lowered the trigger pin holes .07in lower. plus its steel not instead of aluminum so it can take the same finish as the receiver.

For the buffer tab rivets I headed them with a torch before setting them, otherwise they are pretty hard. The rail rivets are smaller and not so bad.

One of my biggest regrets is not learning to tig weld until after I did all the welding. I miged all the receiver parts and they are not very strong, luckily they have been strong enough so far. I strongly recommend tig welding your receiver parts even if you have to pay someone else to do it.

The first time I riveted my rails in I didn't realize a spacer was needed underneath the rails inside the receiver. I don't have the exact measurement on me but make sure your rails are spaced properly before riveting, don't just check the receiver. I used .03in washers to space mine.

That is all I remember doing differently or wrong on mine. I may also be offering a bolt carrier hardening service in the near future since the welding required to make them semi-auto takes all the heat treating out of them.

Last piece of advice, measure 10x before cutting, 2x is still too easy to mess up.

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Re: Help with Build

Postby Trayce1911 » Sun Mar 26, 2017 8:18 am

Sw1ngK1ng wrote:I made a nice jig for welding mine up. I used a block of steel that I machined to fit snug in the rails. Both ends of the block were bored to except a 1in rod on one end and the buffer spring in the other. The 1in rod extended to the front bushing and had a sleeve that fit snug between the rod and bushing. The back of the block being bored for the buffer spring helped a lot in keeping it strait with the rails. Im sure there are better ideas for jigs out there but the more ideas the better.

A few things I messed up or did differently:

I accidentally welded the barrel bushing is a half rotation out of place and had to cut it off and reeled it so triple check that before welding. The cutout one the inside dose on the side that the barrel comes out.

I cut my charging handle hole too far forward and had issues with it falling out when racking the bolt so only cut as far forward as needed. If you do cut too much I welded a short extension to the end of mine to make it stay in.

When welding in my grip mount I welded it to where the grip wanted to sit with the cuts in the receiver, not where it has to sit with the recuperator which was an issue. If I build another I would drill the hole for the front recuperator lug after welding the receiver together then installing it so I can weld the grip mount in the right place. My fix was grinding a small amount off the back of the recuperator with was kinda scary.

The BRP grip is tough to work with because the trigger group is mounted too high and I had to grind too much off the hammer so I made my own. I used the diagram on their site and lowered the trigger pin holes .07in lower. plus its steel not instead of aluminum so it can take the same finish as the receiver.

For the buffer tab rivets I headed them with a torch before setting them, otherwise they are pretty hard. The rail rivets are smaller and not so bad.

One of my biggest regrets is not learning to tig weld until after I did all the welding. I miged all the receiver parts and they are not very strong, luckily they have been strong enough so far. I strongly recommend tig welding your receiver parts even if you have to pay someone else to do it.

The first time I riveted my rails in I didn't realize a spacer was needed underneath the rails inside the receiver. I don't have the exact measurement on me but make sure your rails are spaced properly before riveting, don't just check the receiver. I used .03in washers to space mine.

That is all I remember doing differently or wrong on mine. I may also be offering a bolt carrier hardening service in the near future since the welding required to make them semi-auto takes all the heat treating out of them.

Last piece of advice, measure 10x before cutting, 2x is still too easy to mess up.




Thanks alot that helps some im still looking for rail alignment and spacing measurements, figyre if i have to ill just wing it with the camming block lined up with them. I also dont have to worry about the front bushing as much i uave the whole piece with the front sight still attached so that helps alot

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Re: Help with Build

Postby Trayce1911 » Sun Mar 26, 2017 8:21 am

This us what im working with, the receiver shells are scoth taped together for measuring and marking purposes
Attachments
received_1291593094243471.jpeg
received_1291593020910145.jpeg

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Re: Help with Build

Postby Sw1ngK1ng » Sun Mar 26, 2017 12:01 pm

I don't know if you have seen these or not but I would print out a set. I don't remember if the rail measurements are in there anywhere but if not just call BRP and speak to Brian, he is extremely helpful and full of information. Whatever you do don't rush anything, look everything over really well and mock as much up as you can and try to get an idea of what effects what such as the recuperator and grip mount.

Do you have any machinist skills or is someone helping you built this?

http://www.brpguns.com/content/42saprints.pdf


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