TNW soumi m31 kit build questions

[john2139]

I just picked up one of the m31 kits from tnw and have a few questions.

So first question is when I just lay everything together to test fit there is about a quarter of an inch gap between the lower fcg frame and receiver tube. is that how it is sopose to be or will I need to send it back to have more mill work done?

Second question is when putting the pins into the bolt i have to use a lot of force to have them go in. When I am able to fit them both in the front pin that holds the fireing pin in place seams to tight ans the pin is not free floating. I am unable to push the firing pin by hand.

Any advice or help would be great.

Thanks guys

[nicoroshi]

Shouldn't be a gap between the lower FCG body, and the top tube.
See what it's catching on (and post pics so we can help).

The new bolt has been heat treated after mill work was done. Did you wire brush the carbon build up off of it before you started fitting parts?

[john2139]

Here are a couple pics. Also i dis not wire drush the the parts before fitting together didnt notice the carbon build up looked like a finish not build up.
http://i1166.photobucket.com/albums/q603/john2139/1021120756e.jpg
http://i1166.photobucket.com/albums/q603/john2139/1021120756e.jpg
http://i1166.photobucket.com/albums/q603/john2139/1021120756f.jpg
ThNks for the help guys

[nicoroshi]

Yep, gap no good.
Should sit flush to the top of the trigger housing.

[CALI-gula]

Good info and topic. I would like to see you post info, source for parts, and pics as you go through your build as I've been thinking about building a Suomi myself.

[john2139]

I plan on taking pictures throughout the process for anyone else doing the project because of the lack of any picture walk through in the forum.

[NotEnoughGuns]

The receiver tube should be notched to fit over the top front of the trigger housing. Mine was cut when I got it, not sure why yours isn't.

[john2139]

It ia not notched but eather the notch is not deep enough or not enough on the trigher hoising is removed so back to tnw it is for more machining i guess.

[nicoroshi]

Ask, and you shall receive

http://firingsquad.us/wp-forum/gallery/4-211012213903.jpeg

http://firingsquad.us/wp-forum/gallery/4-211012214057.jpeg

http://firingsquad.us/wp-forum/gallery/4-211012214241.jpeg

http://firingsquad.us/wp-forum/gallery/4-030612215339.jpeg

http://firingsquad.us/wp-forum/gallery/4-030612215308.jpeg

[john2139]

Cool thanks forth pic up loads now i can see that the cut on the receiver cannot deep enough. So I will be calling tnw tomorrow. Now one question when you I was sliding in the two parts of the receiver the bottom lines did not match up the front section having little deeper cut to it.. that is why I'm figuring the the receiver need to be cut more.

[john2139]

So I sent an email to TNW and this was what I received back.


Hello John,

The tube and center section should not have a gap between them. My welding tech said that once the two sections are together tightly you should place the lower receiver into a vice and hammer (dead blow style hammer) the upper receiver down, starting at the weld point where the center section and tube meet, and run down towards the end of the receiver. It will not be perfect because of inconstancies between the old and new parts.

Thought this was funny. Answer is just take a hammer to it and make it fit.

[john2139]

So all cuts done just some final function testing and time to weld her up. Now went to test my friends welder and it is out of commission so anyone in the bellflower area able to lend a hand to me and let me use or barrow their welder or know of a place where I can rent a welder.

[john2139]

So I finished everything today thanks to some friends that were able to lend me a hand and barrow things here and there. I am going to put up a list of the tools I used to do this build

Dremel tool
Used about 6 of the reinforced cut off wheels
Punch set and hammer
Flat head screw driver
Several different sized hand files
Flux core welder

Took about 7 to 8 hours to complete


Here are some images of the project
http://i1166.photobucket.com/albums/q603/john2139/1018122034a.jpg
http://i1166.photobucket.com/albums/q603/john2139/1028122132-1.jpg
http://i1166.photobucket.com/albums/q603/john2139/1028122133-1.jpg
http://i1166.photobucket.com/albums/q603/john2139/1028122134b-1.jpg
http://i1166.photobucket.com/albums/q603/john2139/1030121728.jpg
http://i1166.photobucket.com/albums/q603/john2139/1031121204a.jpg

[00Medic]

Tagg'o.

Lookin good. :thumbsup:

[OniKoroshi]

Is the barrel fully rifled? I heard the newer ones have new barrels compared to the welded extension from before. Just wondering

[john2139]

Nope no new barrel for me. Just the same old weld on extention.

[OniKoroshi]

Ah ok. Still need to build me one of these!

[paratroop]

I just ordered a kit, been planning to for quite some time now. The first lady on the phone said they were on backorder, the lady I was transferred to said they still had a few left. So I'm hoping it will arrive soon. I have been looking everywhere for a build tutorial, it appears no one has actually done one yet for one of these kits. I tried looking for that shotgun news magazine back when there was an article on building one of these, but couldn't find it.

So is the build pretty self explanatory? I am not worried, for I am fairly handy. I might take pictures of the build process and if someone can help me post them maybe we can knock out a good step by step for one of these homebuilds. (I am handy in the garage, but not so much behind the keyboard)

[johnyreb]

Is the barrel fully rifled? I heard the newer ones have new barrels compared to the welded extension from before. Just wondering

I have a production gun and a kit that I built. Both have welded extensions.

[john2139]

here was a good write up I followed

http://www.calguns.net/calgunforum/showthread.php?t=566944

[LCE]

http://wookieswords.blogspot.com/2012/11/finnish-suomi-m31-build.html?m=1

[smirnus3000]

http://wookieswords.blogspot.com/2012/11/finnish-suomi-m31-build.html?m=1
Thanks for posting that up, I'm milling and welding mine on wednesday. I was very happy to see some pics of the build process. I already assembled my bolt and trigger, I have also cleaned up and refinished the stock.

[john2139]

so between the new baby and starting a new job I haven't been able to get this bad boy out till yesterday and ran into a problem.

From what I can tell from looking around online its short stroking.

I'll pull back the charge handle and chamber a round then it will fire. Bolt will cycle back I believe just far enough to eject cassing then load a new one but not far enough to cock the hammer.

Anyone ran into this issue with the m31and was able to fix it?

Thanks for the help

[Arisaka]

That's nice. I wish I had ordered one.

[paratroop]

so between the new baby and starting a new job I haven't been able to get this bad boy out till yesterday and ran into a problem.

From what I can tell from looking around online its short stroking.

I'll pull back the charge handle and chamber a round then it will fire. Bolt will cycle back I believe just far enough to eject cassing then load a new one but not far enough to cock the hammer.

Anyone ran into this issue with the m31and was able to fix it?

Thanks for the help

I literally just fixed a similar problem with mine last night. I thought the same thing, short stroking. But if you pull the bolt back, you will realize the hammer cocks before the bolt even clears the round in the magazine. If the next round chambers the hammer definitly should have been reset. The hammer is not being disconnected. Check the trigger group, mine needed a lot of smoothing out to work properly.(actually I think it works now, I will take my third test fire soon.)

Here's the link to my thread. I had more issues, but got them fixed one by one. Like I said, I think she is good to go now, http://www.calguns.net/calgunforum/showthread.php?t=698595


http://www.calguns.net/calgunforum/attachment.php?attachmentid=205132&stc=1&d=1360985257

http://www.calguns.net/calgunforum/attachment.php?attachmentid=205133&stc=1&d=1360985257

http://www.calguns.net/calgunforum/attachment.php?attachmentid=205135&stc=1&d=1360985257

[paratroop]

I hope this helps. Like I told you I did it a little at a time and reassembled maybe three times before it seemed to function correctly. I can't even get it to stick when I try. I wanted to snap a photo of it stuck, but I only have two hands. Now it is super smooth and crisp.

[john2139]

I see exactly where now thank you so much

[john2139]

Still having a few issues. Tried contacting tnw to no reply. Polished up the triger and bar work for a while then stoped then teued to shim the side as another did nothing. Anyone know of where to by a functioning fcg so I can got shoot this thing.
Thanks
John

[john2139]

Got it working 100% now thanks for all the help cal guns.

But have thought of one more questions. If I replace the bolt and fcg with it then be capable of full auto?

Thanks
John

[paratroop]

Good. I was just fixing to ask you how it worked out. The tube is a reduced inside diameter. Auto bolt wouldn't fit. There are also other small mods that prevent it from being full auto. That is why TNW had to get batf approval on their design before producing them. The atf has funny rules when it comes to tube guns.

[zfields]

Just curious how owners like these guys, and how the production models compare to the TNW kits? I don't have the tools, nor the space to build one at the moment.

[DBoulant]

I plan on taking pictures throughout the process for anyone else doing the project because of the lack of any picture walk through in the forum.

...or anywhere else. Gunbuilds.com has a great one for the demilled kits, not so much for the 80%ers.

I look forward to your walkthru.

[john2139]

There are a couple walk through s likes posted in this page

http://wookieswords.blogspot.com/2012/11/finnish-suomi-m31-build.html?m=1

Thanks fir the information para about the smaller inside of the tube

[DBoulant]

yeah, caught that too late.

Anyone know if threading the barrel for a pinned brake is possible?