Not really a question.  I've read practically every thread on the topic, and downloaded every photo that I can find.

Is there any interest on ARFCOM for me to chronicle the conversion process in this forum?

I bought 6 Suomi magazines last week, and have already begun the process.
I won't have my MAC until later this month, or possibly next month (per the ATF)
Therefore, the final fitting will not be finished until I get my lower out of jail.

However, I can start detailing the process.

Up to now, I have ground the front and rear straps down on 2 of the 6 magazines.  I have been using calibers to measure to match the original M10 Cobray-stamped magazine that came with the MAC.

I won't fit the magazine stops and magazine catches until I get the lower receiver so that I can fit the magazines to it.

My observations, plans, and tools:

1.  You do not have to completely remove the front strap.  If you grind it thin, but leave it, you do not have to weld the seam-- thus saving time, work, and aggravation.  You can get the magazine down to the same diameter by thinning the front strap and thinning/removing the back strap.  The magazine that I thinned the front strap and completely removed the back strap is .30 mm thinner than my original magazine.  I hope that it isn't too loose.  If it is, I may have to build it up again.

2.  I am using a basic angle grinder to the the thinning of the straps. It takes a while, but it works well.

3.  I will be using high-temperature Silver Solder to attach two magazine stops and the magazine catch to each magazine.  I have a good friend who will do the Silver Solder work with me.

4.  The magazines will then be Cerekoted and bake-cured.  I have another friend who does Cerakote and has agreed to do the magazines for no cost.


Is there any interest in my doing a write-up and posting pictures?

Will do, Jeep.

I have this thread cross-posted on Uzitalk in the MAC section.  Already a lot of great input is coming in.  I'll have a cleaned up thread here for our archives.

i'd like to see this too.

To the OP - I've converted over 50 Suomi mags to fit my S&W 76.  A much easier process than a MAC, no need to add stops.  But I've found that grinding away material where the results need to be pretty close to spec, I've been using a Belt sander with 60grit belts.  Just a touch here and there and I'm usually good to go.  Angle grinders have a habit of taking more material of than you really.



Just a FYI.

Thanks for the tips.

I'm really just working with what I have.  I'm not really worried about "taking too much."  My wheel is worn the hell out and needs replacing.  I worry about taking too little.   LOL

I'm interested in this as I currently have 9 of these mags to convert.  They have been handed off to a machinist (a friend of my neighbor) who has had them for several months.  The first one he milled down for me was perfect and from what I heard took him only about 5-10 minutes at most.  So no grinding was done.

OP message me I may have a picture that is not published or found on the net that you might be interested in.

It really depends on what had to be done to the Walther mags to convert them to the MAC.   I'm going to take a look.  My gut says that it can be done.  The question only is what needs to be done.



BTW...

The holidays has me tied up a bit, and the ATF gave me an "any day now" status update on my pending M10/9mm.
I'll be doing some more grinding and picture taking starting next week.  I won't do the final fitting until I get my receiver in.

Lawbob on Uzitalk sent me two of his converted Suomi magazines to toss into my Cerokoting batch when I get mine converted.  I have the benefit of seeing his work.  In addition, I access to blueprints of a conversion done by a very reputable dealer.  I see the skill of the converter (me) as the only limiting factor at this point.

I converted a handfull of suomi mags for my M10  

I did as you said (tho on a mill)  I cut down the front strap very thin,  Removed the back strap.  

Where i differed is the catch   I smoothed out the back spine of the mag then I welded a fairly thick bead across the back of the mag then using the mil I cut the bead flat on the bottom and then milled the bead down untill it fit in the mag well,  I did not put mag stops on as none of my factory mags had them  

one day I will refinish them but for now they have that WWII look about them

Just a quick update.

I will start on the mags again next week.  I found out today that my Form 4 was approved on Dec. 5th.  Hopefully, I will be able to pick up on the conversions and test fitting soon.

OK... update.

I FINALLY got my M10/9mm in. (Will post pics asap.)

I was able to finish grinding down the front and rear straps and fit them to my M10 today.

It was a slow process on the first two magazines, and then I figured out that I was case-hardening the straps by working on one magazine too long at a time. When I started working on two magazines at a time-- switching from one to the next when it got hot-- things sped up dramatically.

I should mention that I have no machining tools at my home. I did this with an angle grinder, a set of calipers, and my M10.

I'll post pictures of the ground magazines tomorrow when the light is better outside.

Next step: Tues. or Wed. I will be bead-blasting the magazines. I'll post pictures of this step as well.

From there, I'll be welding a small strap of metal for the magazine catch and I've decided to also weld a small strip of metal to each side as the mag stops. I don't have the ability to make bulges. I'll post photos at this stage as well.

The magazines will be phosphate finished and set prior to Cerekoting.

At this stage, there will be updates this week, and I anticipated having the process finished next week.

Having LawBob's (member of Uzitalk, and great guy) converted, finished magazines have been extremely helpful just to compare what the magazines SHOULD be like.

At any rate, I wanted to let everyone know where I am on this project.

I didn't post pics of all 6 magazines that I ground down, but this is a good representative sample. This was done using a basic angle grinder. I think that I left enough material to avoid having to tack-weld the seams.

A couple of the magazines had the entire back strap ground off. I didn't need to do that, but I didn't have the MAC to use for fitting. I took a pic to illustrate.

Front strap:




Front Strap:



Rear Strap:



Rear Strap completely ground off:

In. I'm also waiting on a m10

Hang in there on the wait.

Here is mine-- RPB/Powder Springs double-stamp M10/9mm:  Hopefully, I'll have a Lage MkII upper this year.

Well, I am only partially converted on these.  I'm going at a snail's pace due to obligations and work.

Tomorrow, I will be blasting the magazines to prepare them for welding on the mag catches and the mag stops.

I'm outsourcing that part to a part-time worker in my friend's gun shop.  He's a very decent HS kid and a good welder.  He's excited to be part of the process, and I wanted to put a little money in his pocket.

I'll be posting pics again when the welding is complete-- probably mid-next week.

I've got one of the original Walther magazines and the two converted Soumis that I am refinishing for LawBob that I have used as a guide.

Bump for updates.

Also what stock is that?
I'm still waiting on Mac10 to clear a form4. Already ordered a bowers can for it.
Ordering the forward grip soon.

The lage upper is great, the forever backorder is not.

Sorry for slow updates.  I've been up to my eyeballs with work, and have been dragging my butt.

I'll have updates soon.

The stock is a Lage collapsible.  I read that it was not ideal for a M10, but I REALLY like it.  I have no trouble getting down on the sights, and it locks solid in both open and closed position.

I should point out that it may be that I have a high tolerance for stocks.  And AK underfolder never bothered me.