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SGN-9

33K views 295 replies 32 participants last post by  moleman 
#1 ·
Anyone else see the article in the april 20th SGN about the suomi based 9mm rifle? It looks pretty straight forward and the guy said he built it for about $175. I'm sure I have a complete spare set of AR15 fire control parts which would bring the price down as well as various other scrap that could be used. I think I'll order 2 suomi kits and give it a try.
 
#86 ·
I dont think it will fly!! Mic's out at .6145 external. inside is .4035 but theres a flat thin spot on the bottom of the bolt thats only .074 on the case facing and the extractor clearance is also going to be a problem!!. But 7.62x25 is a perfect fit and barells are cheap. not saying you can't but it 's gonna be hard. Chief
 
#92 ·
Thanks

That is a bit tight. I'd probably have to buy one to see. I just upgraded to a SB 10L lathe, so I can (and may) make my own from scratch . I was just hoping to avoid a lot of work. Thanks for measuring for me!
 
#87 ·
I may have totally messed up the bolt.I broke a piece of drill rod off inside the small channel from the backside now its stuck.Wont budge, at all. Drilled firing pin out from front.Wont budge from front. If I can get it out, I'll go from there. I may have to bush entire firing pin hole, no big thing,just need to get that hole cleared. Any suggestions? thanks in advance.
 
#88 ·
Old Grumps you might try Anealing the bolt again which will aneal your drill rod also. Then just drill the whole firing pin out of the front to the step and switch over to the smaller bit size that comes right up to the bushing. I bet though if you drilled out the old firing pin enough to the constriction you might be able to knock it out from the front. The stuck punch is the reason I think the way to go is annealing the bolt then drilling most of the bits from the back which will let you use a bigger punch.
 
#91 ·
Thanks,moleman,but I already tryed that,put it in bbq grill this time,red-hot,let her cool w/ lid closed for a few hours. New cobalt bit just spins. Gonna bite the bullet and order new bolt. Made some stupid mistakes. Not again.Gonna drill hole from behind so I can get bigger punch pin and maybe it wont break.
 
#95 · (Edited)
Old grumps I sent you a pm. What size pipe did you end up going with? I started turning down my receiver tube and now I'm convinced I should of bought a bull nose live center because witht he steady rest I have to make 3 different cuts down to size. With the bull nose I'd only have to make 2 cuts down to size and I could hide where they meet at the end of the end cap threads.
 
#96 ·
I got a little more work done on the receiver tube. Its going to be about the same outside diameter as the original suomi receiver but with a smaller inside diameter. I have two kits and I am going to build up a semi suomi so I'm debating on using sten mags or the suomi mags. I'm also going to finish up a MKII sten build so I'll have those mags also. What do you guys think? I threaded the tube for the endcap (20tpi) and I'm waiting on getting the right size drill bit to drill and tap the barrel extension. Heres a picture of the tube with the bolt in it and the two differnt magwell styles I'm thinking about going with. I also took a picture with the tube mocked up in the suomi stock.
 

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#97 ·
I'm sure it will be easier to install the Sten mag housing, but I think you will regrat not installing the Soumi mag housing later. After all, the Soumi stick mags are only a tad higher in price, but they are 36-rd and the SMG was designed to use them. Also, you should be able to use the 72-rd drums as well, which aren't overly expensive. You need a drum just for show if for no other reason, IMO.
 
#98 ·
Old Grumps, you are most likely already knowledgeable of this, but I thought I would say it anyway. You should start all holes with a small drill bit, 1/8 inch or smaller, and then step up in sizes till you drill the size hole you want.

Using a 3/32" titanium drill bit, I drilled over 1 inch into the length of a standard drill bit. I thought that was pretty dang good as for the hardness factor. The standard drill bit was only slightly larger than the 3/32" drill bit, and looked like a tube after drilling.
 
#99 ·
I fugure it'll be about the same trouble for either mag housing. I'd have to make the sten housing (the one in the photo is for my MKII build) and for the suomi mag housing I'd have to rebuild one of the rear fillers or just make a new one to match the metal lower/trigger housing. The drums do look nice though.
 
#102 ·
No, I hadn't concidered that, it might be the way to go as it doesn't need to be as stiff as the original as it will be supported by the trigger housing. I was thinking about taking two pieces of angle iron and welding a spacer in the middle to get the gap for the mag release. Its going to get welded to the front of the 1-3/4"x1" square trigger housing so it doesn't need the raised edges on the original to retain the stock.
 
#103 ·
I was thinking about the remington setup more for the suomi set up where the trigger has to be set back from the hammer. As you noted the hammer might need a little more mass as the 1100ect firing pins are lighter than a ar15 pin. Although the firing pin head is smaller on the remingtons and they seem just fine with the side to side play. It still looks like it would be a good choice though.
 
#104 ·
Chief, now you got me thinking. The 742,7400,7600 hammers are shaped a little different and look like they have more mass in them for the harder rifle primers.
 
#106 ·
I thought I'd repost the pics of the barrel bushing I'm using since they were lost with the upgrade. I made the barrel bushing long enough that it will go back to the step up in the bolt. This will be similar to the way a suomi receiver is and will limit where an empty case can jam in the action. When I get around to making a semi suomi I'll make a barrel like this one and cut the barrel jacket lugs into it. I plan on attaching the ejector to the bottem left side of the mag well opening in the barrel bushining. Other than that I made a barrel extension and threaded the barrel for 5/8"-18tpi. I have the magwell opening almost done and will get a pic of it up when I finish it.
 

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#111 ·
Matthews went with 1-1/4"x.120 wall seamless 4130 chrome-moly tubing. I went with 1.5" tubing and decided to go for a more suomi type build. I haven't been able to work on it much lately but I've managed to get the magwell hole in the receiver done and the ejector hole roughed out since I last posted.
 

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#113 ·
Thanks Muttman, I'm goning to get an air die grinder to finish the ejector port as I keep running through dremmel bits at an alarming rate and its an excuse to get a new tool.
 
#116 ·
The kits seem to have dried up a little since the article came out. I got my kits from Copes and they no longer show them on their web site. They are for sale on gunbroker, but go for around $100.
 
#117 ·
I have all three articles on the suomi build. I'll see if I can get them on here some how as others have asked also. Probably not today though as I'm getting all the goose hunting stuff out for the opener on monday. Its a neat little project so far. I haven't had any time in the past month to work on my build. The bolt is by far the hardest part of this build so far, but thats just part of the fun.
 
#120 ·
:confused:I hate to say I haven't touched the build since hunting season started. I just got back from Missouri and got a small 11pt and a doe. I'm running out of freezer space and should get back to work on it pretty soon. I want to get it done before obama can ban home builds.
 
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