Went looking for a spare recoil spring for my 2016 HK VP9, but saw they aren't making any more of the OG springs (red ones). Now it seems HK is using the VP40 recoil spring in the VP9 as well, so I grabbed one of the new springs.

I noticed the original red spring made the gun shoot "flatter"...slightly less nose-dive when returning to battery, and seemed easier to shoot for rapid follow up shots. Different recoil impulse.

The silver (new) spring at first seemed softer but really "springy"....slower, smoother, more elliptical, but seemed to nose dive more when returning to battery. After about 25 rounds or so either I was getting used to it or the spring started smoothing out a bit. Not sure, but it seemed different...shot the new one then the red one then the new one again to get a good contrast.

Used 115gr Blazer Brass throughout. No issues.

Two questions then...1) has anyone shot the new spring extensively and can speak to if it is an "improvement", and 2) is there a place where I could get replacements of the older "red" version if I end up preferring it?

The original(red)was #17 the new one is #20 afaik. you can buy an aftermarket spring here which is #18 so should be like the original. The red spring was found to be too easy to push out of battery which is why HK changed to a heavier spring.
https://www.hkparts.net/shop/p...-VP9-VP40-p18543.htm