[deegee]

Spear in NZ makes 5/10 and 5/30 magazines for the HK SL8 for anyone looking for less expensive after-market mags.
They are available in either clear or black fiber reinforced.

http://www.spearmags.co.nz/round-blocked-mags-c-3.html

In Canada they are available from Wolverine Supplies www.wolverinesupplies.com.
However, they currently only stock the 5/30.
The 5/30 mags at Wolverine are ~$45, which is much less than the factory HK 5/10 mag price of ~$250.
The spear mags are high quality and well worth the money.

The 5/30 black glass/nylon mag can be cut down to a 5/10 magazines and correctly re-blocked at 5 for Canada.
This is easily done with a band saw and some cleanup work with a file or dremel.
Note however that this procedure in Canada must be done by a registered gunsmith with the mag being properly permanently re-sealed, and then verified by a magazine verifier, and possibly resubmitted to the CFO depending on province.

 

[fordemti]

I don't think we have those mags here in the states. Can you post a picture?

 

[deegee]

Image of the 5/30 black glass/nylon SL8 mag from Spear.

Note that the magazine has the bottom cover guides duplicated at the 10 round mark.
A cut at this location will turn the mag into a 5/10.
Remove the original bottom and all internal parts, cut the mag shell, re-install the follower and spring (no spring modification is necessary), and one of the five original 5-cartridge blocks, then seal or rivet the bottom back on.
As I mentioned previously, in Canada this must be done by a registered gunsmith.

 

[fordemti]

It seems like it'd work. I don't have first hand experience but I do see hat you are talking about with the grooves.

 

[Hoghead]

New to the forum. I'd be afraid I'd destroy it, I don't have the skill with tools. It seems like a lot of work.
Interested to see how it turns out. Good luck.

 

[F22_RaptoR]

Hopefully turns out well, this would be a good alternative to the absurdly priced 5/10 round mags HK exports to us!