Semi SG43

Hood886 · 09-04-2021, 05:04 PM

The SG43 has been one of the most affordable belt fed parts kits for a while. Unfortunately the kits have really started to dry up. I know there are a bunch out there that have not been built. Building a SG43 has always been a difficult task. In the past there have always been 2 methods.

1. Using a trigger box that stuck off the side of the receiver where an external hammer and trigger could be housed. There just isn't much room inside the receiver. These always had issues as most used AR hammers and didn't have enough force to light 54r primers reliably.

2. Extend the receiver and make it striker fire. Malcolmar/wiselite did this I believe. This seemed to work better but didn't look original and added a decent bit of length to the receiver and still was not the most reliable system.

A newer method was invented earlier this year by Sundance @ weapons guild.com and some production parts were made that included a new piston/mainspring, a striker and sear body. This system allowed for the original receiver to be maintained and for very good reliability.

Basically how these builds work,
1.Receiver denials,
2.Bolt and carrier modifications
3.Rewelding receivers
4.Modifications to spade grips
5.Headspace/ weld halves together
6.Tune and test fire.

I don't have pictures of all these steps but can add them if desired.

Hood886 · 09-04-2021, 05:14 PM

1. The receiver needs two main things done to it. A retainer plate needs to be installed in the front of the receiver so a space is milled out for that. Second is the actual denial where you milk out a several inch section and weld in a hardened bar to prevent a full auto carrier from being installed. Basically this prevents any carrier other than the one fit to your gun from being installed.

2. The bolt and carrier get a couple modifications. The carriers cam track for the bolt is milled down so it no longer can strike where the firing pin is at. The firing pin is also replaced with a full length firing pin and the firing pin hole is opened up to allow room for a spring to prevent slam firing. The bottom of the carrier has a catch on it for the original sear, this is welded up. The piston is changed out to the replacement piston. A slot is milled into the carrier that aligns with the bar welded into the receiver to allow free movement inside the receiver.

3. The receiver is cut into 4 chuncks. These are some pretty decent gaps. I take a bar of aluminum milled down to the correct size and use that as backing and Tig weld these back together at the correct dimensions. I won't go into detail about this unless desired but could talk about this step for hours. I weld the front sections then the 2 back sections together. This leaves me with two halves.

4. The spade grips get modified for the new semi parts and new pin holes. Nothing interesting here just replacing parts and drilling holes in precise locations. A few minor modifications to the grips to prevent full auto grips ect ect.

https://i.imgur.com/6wChrX6.gifv

Hood886 · 09-04-2021, 05:22 PM

5.
Time for headspace. You'll find many people doing this differently. The SG43s bolt locks into a locking surface by camming to the side. Basically cams 15 degrees over or so and locks in. You need to weld these sections together at the correct distance and gap to allow for a proper headspace. Once welded your only options to fix headspace is to either modify the bolt or locking surface or cut it back and weld again. None are easy options. I like to insert the bolt and carrier and have it lock up tight on a no go gauge. I'll get everything tack welded and in place the. Remove the bolt and carrier and finish welding. This allows the receiver to shrink as the weld cools and the headspace will tighten and be good to close on a go but not a no go.

6. At this point there's a few little modifications to make but the main work is done. It's just fitting and tuning all the parts together and making sure there isn't any drag on the system. This one was set on gas port one and was still able to pull the 250 Rd belt around like it was nothing.

https://i.imgur.com/T9htvQB.gifv

Russian · 09-04-2021, 05:50 PM

doubloon · 09-04-2021, 07:10 PM

nice

Black · 09-05-2021, 02:14 AM

Wow, that is beautiful.

DistalRadius · 09-07-2021, 10:11 AM

Serious interest. Left a post on WG, trying to get a Sundance kit. Late to the party as usual. My build would be an absolute bastard since it's already been partially restored (rewelded with denial pins), but oh well.

I'll try to get some pics of mine soon since it's one of the kinda-rare kits with the intact PPN2 night vision and mount.

Hood886 · 09-07-2021, 10:50 AM

Quote:

Originally Posted by DistalRadius

Serious interest. Left a post on WG, trying to get a Sundance kit. Late to the party as usual. My build would be an absolute bastard since it's already been partially restored (rewelded with denial pins), but oh well.

I'll try to get some pics of mine soon since it's one of the kinda-rare kits with the intact PPN2 night vision and mount.

For the most part the reweld and denials are all the same. I'm sure you already looked at his posts but the main modifications that are left to be done are to the bolt, carrier and spade grip. A few things need to be milled out on the receiver but nothing major.

I'm pretty sure they are gonna do a second run but I have a spare kit if they decide not to make anymore that I'd like to make a print of then would be happy to sell it if you cant get one.

strobro32 · 09-07-2021, 03:41 PM

How much to make one work with a M11A1 SMG lower?

Hood886 · 09-07-2021, 06:51 PM

Quote:

Originally Posted by strobro32

How much to make one work with a M11A1 SMG lower?

Not possible unfortunately due to the charging handle. But if mg42/m53 kits were still available. I'm 99% sure I can make one of those work with the SWD 11/9 lowers. When I was building my post sample I took all the measurements and design changes and debated on doing that vs the post sample. Post sample was gonna be much easier and since the kits were drying up figured there was no market for a 42/53 upper especially since it would probably cost as much as the lower. But 16k for a wannabe mg42 is still pretty cheap compared to what transferable 42s go for.

DistalRadius · 09-08-2021, 11:34 AM

Quote:

Originally Posted by strobro32

How much to make one work with a M11A1 SMG lower?

Mounting a Max-31 to the SG43 carriage with a remote trigger is on the "maybe someday" project pileup.

ArevaloSOCOM · 09-09-2021, 01:21 AM

Just amazing

Duce · 09-10-2021, 08:06 AM

Quote:

Originally Posted by ArevaloSOCOM

Just amazing

Absolutely agree
Except for all the serious work to make so many original parts not fit. I can see some small changes but those seem pretty severe. It's like people have not been paying attention to current events.

Dam nice work it's just to bad they had been cut up to begin with.

09-04-2021, 05:04 PM	#1
Hood886 Senior Member Join Date: Jan 2013 Location: Georgia Posts: 1,308 Rep Power: 23	Semi SG43 The SG43 has been one of the most affordable belt fed parts kits for a while. Unfortunately the kits have really started to dry up. I know there are a bunch out there that have not been built. Building a SG43 has always been a difficult task. In the past there have always been 2 methods. 1. Using a trigger box that stuck off the side of the receiver where an external hammer and trigger could be housed. There just isn't much room inside the receiver. These always had issues as most used AR hammers and didn't have enough force to light 54r primers reliably. 2. Extend the receiver and make it striker fire. Malcolmar/wiselite did this I believe. This seemed to work better but didn't look original and added a decent bit of length to the receiver and still was not the most reliable system. A newer method was invented earlier this year by Sundance @ weapons guild.com and some production parts were made that included a new piston/mainspring, a striker and sear body. This system allowed for the original receiver to be maintained and for very good reliability. Basically how these builds work, 1.Receiver denials, 2.Bolt and carrier modifications 3.Rewelding receivers 4.Modifications to spade grips 5.Headspace/ weld halves together 6.Tune and test fire. I don't have pictures of all these steps but can add them if desired. __________________ 07 FFl SOT, I build cool stuff for people who like cool stuff. Instagram @VisionaryFirearms Last edited by Hood886; 09-04-2021 at 05:29 PM.

09-04-2021, 05:14 PM	#2
Hood886 Senior Member Join Date: Jan 2013 Location: Georgia Posts: 1,308 Rep Power: 23	1. The receiver needs two main things done to it. A retainer plate needs to be installed in the front of the receiver so a space is milled out for that. Second is the actual denial where you milk out a several inch section and weld in a hardened bar to prevent a full auto carrier from being installed. Basically this prevents any carrier other than the one fit to your gun from being installed. 2. The bolt and carrier get a couple modifications. The carriers cam track for the bolt is milled down so it no longer can strike where the firing pin is at. The firing pin is also replaced with a full length firing pin and the firing pin hole is opened up to allow room for a spring to prevent slam firing. The bottom of the carrier has a catch on it for the original sear, this is welded up. The piston is changed out to the replacement piston. A slot is milled into the carrier that aligns with the bar welded into the receiver to allow free movement inside the receiver. 3. The receiver is cut into 4 chuncks. These are some pretty decent gaps. I take a bar of aluminum milled down to the correct size and use that as backing and Tig weld these back together at the correct dimensions. I won't go into detail about this unless desired but could talk about this step for hours. I weld the front sections then the 2 back sections together. This leaves me with two halves. 4. The spade grips get modified for the new semi parts and new pin holes. Nothing interesting here just replacing parts and drilling holes in precise locations. A few minor modifications to the grips to prevent full auto grips ect ect. https://i.imgur.com/6wChrX6.gifv __________________ 07 FFl SOT, I build cool stuff for people who like cool stuff. Instagram @VisionaryFirearms Last edited by Hood886; 09-04-2021 at 05:35 PM.

09-04-2021, 05:22 PM	#3
Hood886 Senior Member Join Date: Jan 2013 Location: Georgia Posts: 1,308 Rep Power: 23	5. Time for headspace. You'll find many people doing this differently. The SG43s bolt locks into a locking surface by camming to the side. Basically cams 15 degrees over or so and locks in. You need to weld these sections together at the correct distance and gap to allow for a proper headspace. Once welded your only options to fix headspace is to either modify the bolt or locking surface or cut it back and weld again. None are easy options. I like to insert the bolt and carrier and have it lock up tight on a no go gauge. I'll get everything tack welded and in place the. Remove the bolt and carrier and finish welding. This allows the receiver to shrink as the weld cools and the headspace will tighten and be good to close on a go but not a no go. 6. At this point there's a few little modifications to make but the main work is done. It's just fitting and tuning all the parts together and making sure there isn't any drag on the system. This one was set on gas port one and was still able to pull the 250 Rd belt around like it was nothing. https://i.imgur.com/T9htvQB.gifv __________________ 07 FFl SOT, I build cool stuff for people who like cool stuff. Instagram @VisionaryFirearms Last edited by Hood886; 09-04-2021 at 05:36 PM.

09-07-2021, 10:11 AM	#7
DistalRadius Senior Member Join Date: Jun 2013 Location: TN Posts: 2,239 Rep Power: 30	Serious interest. Left a post on WG, trying to get a Sundance kit. Late to the party as usual. My build would be an absolute bastard since it's already been partially restored (rewelded with denial pins), but oh well. I'll try to get some pics of mine soon since it's one of the kinda-rare kits with the intact PPN2 night vision and mount. __________________ "Nope; these days if you don't have a linkless cam that tilts the breech end of the barrel downwards and locks it to the ejection port and a machined slide with a single locking lug that forms the front of the firing chamber riding on a one-piece polymer frame with interchangeable backstraps and a striker-fired assisted DAO trigger mechanism, nobody will take you seriously." -LoudClankingSound

09-09-2021, 01:21 AM	#12
ArevaloSOCOM Fancy Sauce...... Join Date: Jan 2010 Location: Altadena, Ca Posts: 12,946 Rep Power: 72	Just amazing __________________ "Families is where our nation finds hope, where wings take dream." - George W. Bush

09-04-2021, 05:50 PM	#4
Russian Agent for Good Join Date: Feb 2010 Posts: 6,407 Rep Power: 53

09-04-2021, 07:10 PM	#5
doubloon mEdIA JuNKiE Join Date: Jan 2010 Location: Third Coast - Texas Posts: 15,001 Rep Power: 98	nice

09-05-2021, 02:14 AM	#6
Black Perpetually Cold Join Date: Aug 2010 Location: Alaska Posts: 3,335 Rep Power: 17	Wow, that is beautiful.

09-07-2021, 03:41 PM	#9
strobro32 Senior Member Join Date: Jan 2010 Posts: 4,234 Rep Power: 53	How much to make one work with a M11A1 SMG lower?

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