Hi! I'm Greg Clark. I'm an 07 FFL - non SOT - and spend most of my time over on Weapons Guild. However, I got the bug to build a Form 1 suppressor and became a member here. I lurked and read a lot and then started building. After getting the Form one approved and in hand of course.

I decided to make the gun and suppressor at the same time and selected the Finnish Suomi M-31 as the basis for the build. The Finns had actually played with this idea but as a full auto SMG. I wanted to keep the take down function of the Suomi and knew that it had a robust receiver.



I took a standard Suomi SMG bolt and converted it to my proprietary striker system. I then lathe turned the rear of the bolt to accept a collar that would form rear locking lugs for the bolt. I figured no more powerful than a 9mm is, this would be fine.

The locking lug collar was turned from round stock. The bolt handle came off of a demilled 1903 Springfield bolt. The locking lugs were 4140 and TIG welded to the collar.



This allows the locking lugs to rotate but the extractor and feed lips to stay centered at all times.

Here's a shot of carefully hand fitting the lockup of the lug on one side. There's another lug on the other side.

Here's a shot of the major parts being fit together. I'll spare all the other details unless someone wants them.

The basis of the suppressor is the welding of a steel tube to the original heat shroud stub end. This shroud is removable - along with the barrel on the Suomi.

This is a good strong design - but heavy as hell!

Here's a rear end view showing the Suomi barrel locking lugs and the chamber end of the barrel.



And the barrel out of the tube. The freeze plug shown on the barrel is an end support for the barrel and it partitions the tube into a rear reflex area and a front baffle area.

Here's a shot of the drilled barrel (I added 3 more holes per row later), the un-welded stack of freeze plugs and one drilled freeze plug not in the stack yet.

I used a snug fitting bolt to keep the baffles aligned during welding and then lathe bored the final size after welding.

The large openings at the muzzle are on the baffle stack end of the partition and are there to try to dump more gas prior to the bullet unplugging the bore. The rifling was bored out from these openings to the muzzle to avoid bullet contact.



You can see the four 8-32 screws I used to hold the partition into the main tube.

Off to bed - my eyes are crossing!

More later.

This is looking interesting.

Welcome and thank you for sharing your innovative and well executed idea.

I am always overwhelmed with the results of the enviable skills that are daily demonstrated
at the Weapons Guild. Like being let loose in a Austrian chocolate pastry shop with
a stein of Würzburger Hofbräu. Which one to sample.

Best.

Welcome to the board, very cool, thanx for sharing.

I haven't seen a build like this since... Homegunsmith.com.

I forgot how much I missed these! Please keep posting your progress.
Are you going to keep this magfed? If so, this may end up being the single coolest 9mm bolt gun ever built!

Hi All! Thanks for the kind words. I figure I have taken enough wonderful knowledge from this board that I owe a pay back.

Yes - it accepts the 36 round stick mags. 50 round coffin mags and the 72 round drums.

At the end I'll post a video or link.

Here's a shot of the baffle stack after welding, through boring and sandblasting.

Test fitting all the major parts. Note the two sets od screws in the suppressor tube. The ones near the muzzle hold the baffel stack in.

Remember, the major portion of the chamber pressure has been dumped through the varrious openings in the barrel so a "blast chamber" is not really needed.

One more shot of the locking recess design - sort of out of sequence.

In order to keep this from being a "two stamp gun" I set screwed (into recesses) and welded the can tube to the barrel. The can tube is 16+ inches long to keep it from being a SBR.

The original take down latch still works so the gun breaks down into two units.



Also, where the arrow points, the original Suomi barrel indexing tab was removed so the entire front unit can rotate for takedown.

Why did you weld the baffle stack? Now you cannot clean them.

Also, why did you use freeze plugs when you have access and skills on a lathe?

My whole idea with this build was to see how simple and inexpensive I could do it and still have a good final result. The cleaning issue can be taken care of by soaking and air blasting.

The freeze plug issue was, again, K.I.S.S. I had some theories on suppressors and wanted to look at them in action.

My first theory is that building a suppressor is like building a racing engine. There's no substitute for cubic inches.

The other one is, the only reason for the alphabet baffles (m,K etc) is if you can't afford the cubic inches (large size) then you have to substitute technology.

My first build more or less validated my suspicions.

Here's the final product. I will also try to post a shooting video of it.

And a video from YouTube -

http://www.youtube.com/watch?v=tYy_yDsvvxc

Great post and great results. Thanks for documenting this for us!

Glad to be of help!

As we say over on Weapons Guild - Knowledge not shared is knowledge lost!

If anyone has questions - I'll try to answer.

Have you milled it for the magazine feed yet? I didn't see that in the video.

That's really cool.

Just out of curiosity... Wouldn't a manual side / strightpull AR be a lot easier? Instead of using the 9mm blowback bolt, modify the 223 bolt (does it even need it?) and just not use a gas system all on a side charge AR... Hmmm... I may have just cost myself a bit of money right there...

It's apples and oranges to what you have there, just thinking out loud. Really nice good job though.