We have all lamented the absence of new factory 39 mags for a while, and I am not immune from this. I have several, but like always I prefer the option of using available modern factory mags and keeping the old ones aside for a rainy day.
Enter the 3904/3906 mags. Nothing wrong with these in a model 39-2 EXCEPT that they are an eyesore hanging out of the magwell like duck bills.
IMG_1631.jpg
Heres the good news:
The model 3913, arguably the best single stack 9mm ccw pistol of all time, came with two magazine AND TWO FLOORPLATES EACH.
They look like this:
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Now, a while back I discussed the use of Pachmayr sleeves on 3900 mags for use in the 3913. Looks like this:
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So looking at that 3913 and its associated magazine floorplates, I swapped some around.
Turns out the 3913 “flat” plastic floorplate on the 3904/3906 mag looks pretty nice in a 39-2.
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So I made some up.
THEN I got to thinking about springs and followers and capacity over the generations.
The 39 came with 8-round mags, as everyone knows. At some point they switched to black plastic followers. Work great and hold 8 rounds. These have flat steel floorplates. Look like this:
IMG_1640.jpg
The guts from that mag removed indicates that the follower design has changed a bit in the 3913 mag, ad well as later 3904 mags. The 39 follower, the early orange 3906 follower, and the newest red 3906/3913 follower are a bit different. More to follow.



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The followers together:
IMG_1638.jpg
So I swapped some around from magazine to magazine and this is what I found:
The 3913 red follower and spring are exactly the same as the late 3906 mags. In the 3913 mag body they hold 8 rounds BUUUUT in the 3904/3906 they hold 9 rounds.
THEY ALSO WILL HOLD 9 ROUND IN THE MODEL 39!!!
The red follower and spring from the 3913 placed into the 39-2 magazine makes it a 9-round magazine with no other modifications.
This morning I loaded up several configured this way and fired 300 rounds through them and had no malfunctions of any kind.
In summary, the latest red follower and spring makes the early 3906 mags and the model 39-2 mags nine-shot mags, and the 3913 floorplates fit and feel better in the 3906 mags for use in the 39-2.
I hope you all have fun swapping parts!
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Some of my happiest moments come from "swapping parts"!

Good detective work on your part!

John

I have several of the longer body magazines with the correct floorplate that fills in the gap on the 39/X39 pistols. I have also converted all of my 8rd 3904/3906 magazines with the newer red followers. Using the 3913 floorplate is a good idea.

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Thats an interesting floorplate. Do you by chance have a part number? I have never seen that one before.

I have never found a part number. I sent S&W this picture and description once to see if they were still available and was told the part was long gone.

Attached Images

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Interesting. Not to be a pain but could you remove one from a mag and take a few pictures of it? I want to try and reproduce this from nylon.

Thanks Matey! This is very interesting and very useful. Now if I could just turn my 39xx magazines into pre model 39 magazines (with correct stampings) I would be extra happy!

__________________
John 1:17
NRA Life Benefactor

Squidsix- Is the Pachmayr sleeve something that is still available? Is there part number or description that would help when searching for said sleeve?
Couldn't find the thread where you mentioned it in the past.
Thanks

Here you go:
Pachmayr Mag sleeves for Kahr MK9 on 3913

Just scored a couple of blued 8 round metal floor plate 39 mags at pawn shop for about 8 bucks . Looks like the only real difference in the follower is the tail on the 8rnd black one is longer. Looks like trimming to the length of the red one will make it a 9 rnd one. Anyone try this?

Thanks,
Rosewood

Thanks Squidsix for your research and postings.
I had stumbled across your post from 2018 on DIY modifying the Pachmayr sleeves with a little sanding to match the S&W magwell angle; and scored some NIB S&W 3906 mags and sleeves from Midway at a good price (Birthday discount). Perfect 9+1 for my 3913NL!
Thanks Again for sharing your knowledge. -Vinny

I did try the red follower in the mag and it will not allow 9 rounds in it. I do however believe if I trimmed the follower, it might allow 9 rounds. I also noticed the body of these 8 round 39 mags are about 1/8" shorter than the 9 round mags.

Rosewood

I too ordered the Kahr Pachmayr spacer and fit it to my 3906 mag as my backup mag for my 3913.

Thanks guys.

Rosewood

Hey Mr. squid, why do you keep orig. fac. 39 mags for a rainy day?
All of mine from the 50s and 60s function perfectly with fac. ammo.
There were only three follower variations, and two base plate variations .
The mag. body was fairly std. with the exception of the military cut out variety. Just curious. Mike

__________________
Mike 2796
SoFo Bunch member

I include 8 round factory mags with guns if I sell them, vice modified mags.
I also like having at least a few of them for each gun that I have the original box for, making as complete a package as possible for those guns.

I did a little more experimenting. I discovered you have to change the floorplate catch assembly also. The factory one in the 39 has a hump in it that stops the follower just enough that it won't take 9 rounds. When I used the newer flat catch assembly, the mag will indeed take 9 rounds with the red follower.

Rosewood

The factory original 39 mag spring will not allow 9 rounds with the new follower and floorplate catch assembly without modification. I failed to order new springs. Finally figured out the older 39 had 1 more coil than than the new 9 round 39 mags and 8 round 3913 mags. Cutting off that last coil was just enough for 9 rounds to fit. So by changing the follower and floor catch plate, the metal bottom 39 mags will now easily hold 9 rounds and have been 100% reliable so far. May end up ordering new factory springs for the 9 round mags and upgrading soon for good measures though. I did discover the 9 round 39 magazine and 8 round 3913 magazines do use the same spring.

Rosewood