Where can I get a magazine for this ancient relic? All I have been able to find so far are $100+ original magazines or over priced Triple-K knock-offs for around $40. If memory serves me correctly Triple-K is almost as bad as ProMags.

Are there any other .380 acp magazines that will interchange in this pistol? The old school heel magazine release seems like something that could accept a different magazine provided it was the same length and dimensions. It's not like having to make it line up with magazine release buttons.

If it is the Interarms version you only need one mag.  You will be lucky to get through it with only one stovepipe.

I might,maybe,could have one.I will look.Seems like I had a factory box too.
Someone stole the pistol......(I know who did it)
Give me a couple days to look for it...........

I sold my Interarms HSC a few years ago, and I never checked to see if my HK4 magazines would work, but the HK4 was based off the Hsc.   P38 mags work in a HKP9s(9mm) but wont hold the slide back, but work perfect otherwise.....so it wouldn't surprise me

Are the Triple-K magazines junk?

I am nearly 70 years old and have been hearing Triple K magazines are junk for years.  Obviously this is not the end all response to your question, but, I have only had one Triple K magazine.  It was for a Savage .32 acp pistol and I have never had a malfunction with it.  My experience will have me buying another Triple K magazine should I ever need to make a pistol operational.

I bought a couple to try. It seems to be my only option.