Has anyone attempted this before?  I have a couple 10 rounders that dont serve me much purpose aside from range shooting.  If no one has done it, how do I take these things apart?

Sweet!!!! I figured it out.  I took one apart.  All you have to do is break off the tabs, ditch the lower piece that the spring rides on top of and secure the baseplate to the body of the mag.  I used some electrical tape for testing, but the JB weld is about to come out for permanent deal.  Ill probably drill out holes for the rest of the 15 slots too.  

Maybe I'll order some 15 rnd mag springs.  These felt a bit weak, but I fed a couple mags through it without any hickups.

This isnt as cost-effective as I had thought.  Replacement springs for these things are $7.50 each  I may just run the 10 rnd springs until I have a hiccup.  It may be hard to get the baseplate off if I JB weld it on there though.

EDIT: Pics I promised, simply break off the tabs at the base and ditch the other thing I X'd out.



Half-assed finished product




Are there any legal issues involved with this?  There is no mag capacity limit in my state.  These will be my last resort for personal defense.  I just have a 3-gun coming up and want some extra capacity.

final product


The JB weld is a bit excessive, this is the first copy.  The second one is still curing and looking a bit cleaner.

Looks good. Would like to do that to my 10 round mags. Let us know after you have used them a few times on how they finally work.

I would use them as range mags only, not for CCW.  Nice work, though!

Theyre going to be my last mags for 3-gun.  I have 3 real 15 rounders, but these two may be needed.

Took them out last night.  Put 100 rounds through them and had no problems.  

Nice job especially considering the cost of replacement mags

Call me HK ignorant, what caliber are those?

Quoted: Call me HK ignorant, what caliber are those?

15 rounds = 9mm I'm pretty sure.

Roger, they are 9mm.  I'm going to a shoot this weekend, hopefully they stand up.  I did some fairly rapid fire with them and they had no hickups.  They could use 15 round springs, but I think I will be okay for a while.

Neat conversion but as mentioned above I wouldn't use it for my CCW.

BTW, what do you do when it's time to change the spring in those converted mags?

I can break the JB weld.  I jacked one up, the spring wasnt seated right and I had to open it.  I put it upside down with the baseplate overhang on the edge of a table and hit down on it.