Not to confuse the issue more but can I use these extensions on my VP9/P30 full size mags I'm using in my USP 9 compact I'm using with the little "spacer" things I bought from HKPro.net and/or can I use these on the mags as I use them with the spacer things as I use them in my P30SK?
I don't know for sure? I have an X-grip adaptor on a couple my full size P30 mag's I use with my P30SK. That is the extent of my experience with X-grip adaptors. Seems to me, and this is totally from memory so take it for what it is worth, the X-grip ("spacer thing") is formed to specifically match up with the factory magazine base plate, adding these adaptors would alter the interface surfaces between the X-grip and the new extender/base.
I guess in short, I'm not really sure? But I understand what it is you are asking, so there's that??????
for what it is worth, I've used the TF HK45 extensions, and had really good luck with them, no malfunctions with man, many rounds run through them. So I can attest to the quality of the TF extensions. I've been pestering HKParts about the full size HK45 extensions they are working on. I've been told they are in the works. I've not used any of the currently available HKParts extensions, so I cannot speak to their quality, that said I've always been happy with the HKParts manufactured parts I've purchased in the past, and have no reason to think their mag extensions will anything other than high quality and reliable.....