Originally Posted by ken grant
If this is so, why can you take a new mag spring and have a hard time loading it but you can fully load it and let it set awhile and it gets much easier to load.
Also a new spring will shorten after being fully compressed for a while.
The spring length at rest is not a specification of the spring. Springs are defined by a force curve with respect to an absolute compressed length. Typically, the first ~20% of compression is not linear nor part of its design parameters. The extended length you speak about in your example has no relevance to the mag assembly function - it is compressed well beyond that point at rest when assembled.
When a magazine follower and spring assembly is compressed, there is a lot more going on (mechanically) than simply a spring compressing. However, I am not disputing that when the spring is brand new, and you compress that spring, the length at rest is inconsistent, or its first compression curve is identical to that of compression number 10, 50, or 5,000. I am saying that the spring is designed to behave in a specific manner over its lifetime. The first few compressions are not of consideration, and over a lifetime of compression cycles, it will fatigue...but, leaving it compressed for an infinite amount of time (after the spring is cycled a handful of times) will not produce any measurable difference in behavior. Cycling it 10,000 times while leaving another identical spring compressed will show a decrease in force/change in elastic limit with the one that was cycled. The only way to truly get 'spring set' is to introduce heat or over-compress it (would require disassembling the mag and stretching the spring or a heat-treating oven).
No reasonable person with the slightest hint of an engineering background would specify/choose spring characteristics that would be affected by leaving a mag loaded. ...especially not these days.