A powertube spring?

[In My Sights]

I was a my local shop this weekend asking the tech about the powertube spacers to stop my leak (it leaks down the barrel and the powertube o-ring is brand new). When I got my minimag, I did not get any spacers other than the one in the powertube. He is AGD certified so I value his answers, but he gave me a powertube spring rather than selling me a spacer kit. And the spring stopped my leak.

I forgot to ask him while I was there and to be honest, I was kind of wondering if the spring would really solve my problem. So my question is this, if the spring stopped the leak and will "adjust itself to provide the correct amount of o-ring pressure" (as he put it); why can I not find a powertube spring listed on any of the parts lists? Is this just "old" technology that has been improved upon?

[ghtpDM5]

it hasn't been carried in awhile to my knowledge, but i use springs in my powertubes to great effect and have for years. i have no powertube leaks usually, and my mags perform rather well

[Spider-TW]

The springs are old tech, to be sure. I skipped the 'spacer age' and went from springs to level 10 kits. I've heard that the springs can get old and weak, but I've never seen one that caused problems. There's no part changing with the springs, and I have never understood the trade-offs in benefits with spacers. It should last you until your next upgrade or at least your next full rebuild.