Hakkaa päälle! (Suomi M31 review) Updated- Range Report

[Precision]

can't speak for others, but I like the follow up and the little details of your experiments.

[Steamforger]

Seriously. I read the updates when they come up. I'm currently resisting adding into my Cherokee thread about my on-going fight for better MPG. And yes, the tires are correctly inflated.

[Netpackrat]

Kewl. If all goes well, AlaskaTRX and I are going to try to hit the range tomorrow morning before I have to get ready for work, and I'll try the new loads then. This is only a fun gun, and not something I will be depending on for protection, but it will be a lot more fun if I can come up with some more handloads that it is reliable with. What I've been able to load so far has been dependent on what projectiles I can find, but it seems to distinctly prefer round nose FMJ, as I had expected it would.

After that I need to start working with the drums; they still need to be de-cosmoed and test fired. I want to make sure that they work right in the gun they are intended for before I try to use them in the next project which I have been accumulating parts for. My gunsmith friend who helped me with the Suomi has built several 9mm AKs that take the Suomi drums, and I am going to have him build one for me. I've got nearly everything I need at this point except for a barrel blank, and I got a shipping notice on the AK-74 receiver a day or two ago.

[Netpackrat]

And, I still got a few jams with the 115 grain round nose FMJ reloads. Should have brought some of the factory ammo (that was okay before) with to compare. Seems to only happen when the mag is full or mostly full. Real interested in trying one of the drums again.

[Combat Controller]

Try Protek. It cleaned the crap out of a bunch of Cosmo'd rifles for me. Easy peasy.

[Netpackrat]

Try Protek. It cleaned the crap out of a bunch of Cosmo'd rifles for me. Easy peasy.

Thanks, I will keep an eye out for that. I was just going to use gasoline.

[Netpackrat]

Hadn't done much with the "Mowing Machine of Tikkakoski" in a while out of frustration at intermittent feeding issues with the stick magazines, and absolute lack of feeding with the drums. I did make one more attempt at getting a drum to work last year (I did a more thorough job of de-cosmo'ing one to see if that helped. It didn't.), but that was about it since 2013. What changed is I now have a pistol can ordered, the deadline for 41F is coming, and I really want to Form 1 this so I can put an original length barrel/shroud on it, and then cut the barrel and shroud I currently have even shorter than that, and have it threaded for the can. But I'd prefer to have it working somewhat better before committing the $200 to that. There are far better choices for a pistol caliber carbine, and I will probably get me some of those too. But I just like the Suomi because it is cool.

One thing that's been a constant annoyance since I bought it is the draggy action, which could very easily be causing the misfeeds. In its original form, the Suomis had a very nicely machined bolt, tightly fitted to the receiver. The fit was precise enough that they used an air valve at the rear cap as a buffer, to control the rate of fire. If you've handled an original Suomi bolt, the surface finish is very good.

The bolt in the TNW rebuild, is not really any of that. In order to mollify the ATF when rebuilding an open bolt subgun into closed bolt semiauto operation, the receiver must be made so as not to accept an unmodified, full auto bolt. In this case, the I.D. of the receiver is slightly smaller than original, so the FA bolt won't fit. The modified semi bolt has been turned down to fit inside the smaller diameter tube. The problem being where the originals had a smooth, polished surface, TNW appears to have bead blasted theirs and then parkerized it. It moves well enough when drenched in copious amounts of lube, but in use it tends toward dryness and gunk. When hand cycling the action using the charging handle, it even liked to hang up all the way back until the butt of the gun was smacked against a solid surface.



I think it would have worn in eventually, and you can see where that is starting to happen on the wearing surfaces in the above picture. Unfortunately I am not patient enough to keep running it and hand cycling it to see if that improves the reliability eventually. So, tonight I did a little polishing on the wearing surfaces of the bolt:



I started with an 80 grit belt on my expander wheel, and worked down through progressive grits to 320. Then I hit it with emery compound on a sisal buffing wheel, followed by tripoli on a spiral sewn cotton wheel. I wasn't going for a perfect polishing job (otherwise I would have hand polished it with emery cloth... blechhh...) and there are probably some uneven areas and scratches I didn't quite get out. But I put some lube on it and reassembled the rifle, and it seems to work a lot better now. I can't make the bolt hang up to the rear anymore even if I try. It made enough difference to be worth dragging to the range for another test, anyway.

[Combat Controller]

Looking forward to the outcome. I will say though, the advantage of a SBR AR lower is the sheer number of calibers including pistol, you can shoot off of it.

[Netpackrat]

I will say though, the advantage of a SBR AR lower is the sheer number of calibers including pistol, you can shoot off of it.

Yeah, I have one of those, too. I will have another one once ATF approves the paperwork, because sharing is for suckers. Right now it makes more sense to buy stamps, than to buy uppers for what I already have stamped. I can build one of the lowers into a 9mm at some later date.

I don't like ARs anyway, and owning one hasn't done anything to alter that. The stupid thing jammed up at the range last week at a relatively low round count since cleaning, evidently because I hadn't slobbered enough oil on it.

[Combat Controller]

I will say though, the advantage of a SBR AR lower is the sheer number of calibers including pistol, you can shoot off of it.

Yeah, I have one of those, too. I will have another one once ATF approves the paperwork, because sharing is for suckers. Right now it makes more sense to buy stamps, than to buy uppers for what I already have stamped. I can build one of the lowers into a 9mm at some later date.

I don't like ARs anyway, and owning one hasn't done anything to alter that. The stupid thing jammed up at the range last week at a relatively low round count since cleaning, evidently because I hadn't slobbered enough oil on it.

Or too much!