To each his own. I don't think its much of a bargain at all but that's my opinion as a pro-tuner having tuned hundreds upon hundreds of guns over the span of many years. It may be just a bit stronger but personally I think it's a terrible spring to use because of the characteristics of the spring when there are a couple of far superior springs. As I said, you get what you pay for and though the JM springs may cost more, I for one can tell you that of the hundreds and hundreds of JM springs that I have bought over many years and installed, I have had only three of them break that I'm aware of and two of those were from admitted abuse. But the JM springs are subject to wear and tear just like any other spring and with time will fatigue eventually and perhaps even break. No spring is infallible, indestructible, or expected to last forever.
Unlike the Chinese guns, most Gamo's that come through have plenty of lube on the spring, in fact quite often, way too much. Although spring vibration and harmonics doesn't do the spring any good, it is rarely why a spring breaks. I have tuned guns that were many years old and had many thousands of shots through them that were dry as a bone with all kinds of vibrations including Chinese springs that were not broken. Harmonics and lack of lube didn't break those springs. There are many factors that cause spring failure or fatigue. The wire can be too soft, too brittle or contamination when the wire is drawn and defective. Pretty easy to see when looked at under a microscope. Then there is abuse, when guns are dry fired, too heavy a pellet or too light a pellet, bad piston seal, detonation, spring cant or a combination of any or several of the above. There are a couple of other reasons also.
Bottom line, unless you have good uncontaminated wire using the right steel composition, well drawn and formed and properly treated there will likely be premature spring failure. Well manufactured springs cost more because they use high quality wire and stringent quality control. Me... I use nothing but JM springs for not just Gamo's, but for RWS's, FWB's, Chinese guns, AA's, Crosman, Wischco, Remingtons, Winchesters, Norico, BSF and all of the others that I work on because it's not worth it to me to use nothing but the best for my customers and recommend/suggest to others nothing but the best. Until someone can show and prove to me a better spring for the money, or even more money, the JM springs is all I would ever promote. As I said previously, you get what you pay for. Let me say that I'm not condemming the Quest spring. What I am saying is the Quest spring is far from the best alternative but by the same token, fills a need for some and that's fine. I just don't recommend them.
