We're putting Dewey "through the paces" with all these questions, but I have so many, and it's so rare to be able to get opinions developed through long experience fixing these guns.
If we've not worn our welcome too thin, Dewey, I have a question about your opinion concerning the failure rates of V springs compared to coils. Most today assume that coils are superior, due to their ease of manufacture and their so-called ability to continue to function even after breakage. Perazzi guns continue to use V- springs in their locks, and get hammered for it by K gun shooters. I'd be interested in your opinion of that.
Kim Rhode, Olympic shotgun medalist who has shot Perazzis for over 16 years, stated that in shooting 500-1000 rounds a day for 16 years she has never had a malfunction in practice or in competition. I have never had a breakage in the two I have owned. My idea, and it's only an idea, is that the life of a V spring is much more highly dependent on the quality of the spring than with a coil spring. Said differently, it's enormously easier to produce a quality coil spring than a quality V spring. Am I all wet?
SRH
I wouldn't worry too much about razzing from anyone who shoots a German-made Remington. Before the lynch mob forms, that's humor, FFS.
I'm pretty sure that Perazzi offer both coil and v-type springs, at the buyer's discretion.
On to springs. This is going to be a bit long but when I'm done, you will see that there is no answer to the question of which is "better", V or coil. It all depends upon the application, the available materials, the available craftsmanship and the consumer's perception.
First some theory. It isn't readily apparent to the casual observer but what we are really talking about when discussing coil (or spiral) springs is in actual fact a torsion bar. A torsion bar is a spring in the form of a (usually) round shaft in which one end is anchored and the opposite end is free to rotate about the longitudinal axis. The spring rate (or stiffness) becomes less as the length is increased, and the rate increases (becomes stiffer) as the length is shortened. A coil spring is nothing more than a clever way to package a long torsion bar in a short space. As a coil spring compresses it is actually twisting through the wire cross-section throughout its length. For a given material, wire diameter and pitch, a spring with more coils (longer torsion bar) will be softer than one with fewer coils (shorter torsion bar). If you cut a coil spring, it becomes stiffer. At this point I will address everyone who has ever cut a spring to "make it lighter". You did not make the spring lighter, you made it stiffer. What you DID do is to decrease the spring's length and therefore, its INSTALLED PRELOAD. Less installed preload gives the illusion of lighter spring. This is easily demonstrated and therefore proven with a pair of sidecutters and an old 1911 recoil spring. Stick a loose-fitting dowel through the spring and compress it by hand, you'll be able to move it pretty far. Now clip 4 coils off and try to compress THAT piece (good luck).
V, or leaf, or flat, springs are in actual fact beams and simple beam theory will suffice to explain their operation. Imagine a solid beam, supported at each end on the bottom, with a force applied at the middle of the upper surface.
The forces that the beam is actually experiencing are as follows:
- Compression along the top surface
- Tension (stretching) along the bottom surface
- Cancellation of both forces through the neutral axis
The neutral axis is the cross-sectional midpoint of the beam. If the beam is a simple 2x4 stood on edge, the neutral axis would be at one inch from each edge, or the midpoint. The opposing compression and tension forces steadily diminish as they reach the neutral axis. This is handy and applicable when designing a wing spar because we know that material can be safely removed from the area around the neutral axis, saving weight while maintaining adequate strength. When it comes to a mainspring, we're not so concerned about weight but knowledge of the forces involved is still useful.
A flat spring will behave EXACTLY like the beam described above, but what about a V-spring? A V-spring will behave exactly like the above beam, plus its mirror image. When a v-spring is compressed, Its entire outer surface is in tension and its inner surface is in compression. As one might imagine, a surface imperfection in the tension side of a V or flat spring may well act as a stress-raiser and give rise to a crack. The same holds true for a torsion bar, whose entire exposed surface is in tension.
Thus, a spring, of any form, made with completely defect-free material and a completely defect-free finish, properly heat-treated and never subjected to a load that exceeds the material's tensile limits, should last forever. This is what I try to achieve with every spring I make. It doesn't always work out the way I'd like.
