Nelson actually sells three springs which are color coded. 8, 9 and 10# I have two of the Nelson conversions with more than 5,000 rounds through them. They run 100%. I had some feeding issues on one of them when it was new which I couldn't figure out. I sent the complete gun back to Larry and he found that the thumb safety was rubbing a little on the slide. He fixe4d this and the gun has been perfect ever since. Can't comment on Tacsol because I've never had one.