I had one of the HK4's. Use caution, you will find it extremely difficult if not impossible to find any parts should you need them.
BTW, I sold mine because I was having feed problems with the .380 barrel. The .32 barrel worked like a charm though.
Unless you want that pistol as a collectors item, I would suggest you get a more modern design.
I would highly recommend the German made PPK/S and the Sig P230/232. Both are magnificent pistols and easily serviceable.
CMOS
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GOA, TSRA, LEAA, NRA, SAF and I vote!