Mizar said:
Walt, Tarosean makes an excellent point, because dry firing "aficionados" do induce stress to some of the springs way more than with live fire.
No more stress than would be the case with the same number of trigger pulls done via live fire. And stress may not be the appropriate term. It becomes stress only if the design of the spring allows it to be pushed too far. Most springs aren't pushed too far. I agree with tarosean that dry-firing causes stress on the trigger return spring, but its apparently not a great deal of stress with most guns. (How many examples of broken or failed trigger return springs have you experienced or personally know about?)
Mizar said:
And every spring will suffer from metal fatigue soon or later. And it can (and will) break. Every spring has a life span, but this does not mean that it will break at 5000, or 10 000 mark - it depends on design, care and etc. It is a rare occurrence, but it can happen.
Not entirely correct. It's not that simple.
Every spring that is used will suffer from some reduction in its ability to work over time -- but that does not mean that every spring that suffers from that sort of deterioration will break or stop functioning as it should. It may just NOT perform as well as it did when it was new, but it may still keep on functioning so that you don't really know the difference.
Tappet springs in most auto engines will outlast the rest of the engine -- even though they've cycled many, many millions of time over their work life. While every spring may truly have a life span, that span does not necessarily end with the spring's failure or breakage. It may, instead, end when the machine in which it works breaks down for other reasons (as in a thrown rod in a car engine) or is put to rest (ala an auto junk yard, a gun buyback program, or when the gun isn't maintained and rusts away, etc.)
Most COIL springs in guns don't break -- they lose structural integrity from countless micro-fractures within the material when they're compressed too far. Many coil springs are never compressed too far.. Coil springs spread the work through much of the spring body, unlike other springs. Most often, they fail by becoming soft and being unable to do the work. Flat springs will break, but they'll also sag. It's only with the weakness (due to OVERWORK -- pushing the spring beyond its elastic limit) causes the spring to prevent proper function that you even notice the problem.
A
trigger return spring isn't a coil spring, even though it is coiled -- It works more like a long flat spring that has been wrapped around a fixed bar. I suspect more of that type of spring's material is working than is the case with some flat springs. If a trigger return spring gets pushed past it's elastic limit (the point beyond which it starts to deteriorate) it may break, or it might deteriorate just enough that it can no longer return the trigger to its forward position.
Gun designers have no need to put a trigger return spring in that part of the gun that is too small or made of too-little material, as is the case with the recoil springs in a very small semi-auto or the magazine springs in a very hi-cap mag. They can easily design longer-lived trigger return springs without having to compromise their size or materials. Except for special needs, like very small guns or very high capacity magazines, most gun designer don't need to build a gun that "uses up" it's springs!
Mizar said:
No, thank you, this is the exact reason I strongly dislike full power sub-compact pistols - too much dependability on springs to function right.
I understand. That's a reasonable point of view. I suspect that also means you're not a good candidate for one of the Rohrbaugh R9s, then. That may be the smallest 9mm semi-auto you can find!
That gun's recoil spring has a recommended service life of 250 rounds. That small spring has to fit in a very small area, and has to do the work normally done by a larger springs that fits in a larger area; to do the job, that spring has to be pushed to or beyond it's elastic limit. When those springs fail, they don't typically break, but they do lose the ability to chamber the next round.
Happily for the people who own them, those small 9mm guns are well made, the springs are cheap, and the guns go inconspicuously into places (like front pockets) where no other 9mm guns can go. They are dependable as long as the owner replaces the recoil springs frequently, and keeps good round counts. (Those springs will actually perform beyond 250 rounds, but these higher-round-count recoil springs are best used at the range, if the owner ever wants to practice with that small gun! I doubt that I'd practice much with one of those small sludge hammers!)