doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Reinforcing Stereotypes, Failures & Anomalies

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.

Excellent explanation. More than I had hoped for.

Thanks again for all you contribute to the double gun community.

SRH

Stan- re Kim Rhode's Perazzi, she stated that it was an MX12 she was using, the model with COIL springs.

Dewey above states the engineering and physics of springs accurately. The point though is that in most cases it is easier and much less costly to deal with a broken coil than a V spring.

Price estimates for the replacement of the more exotic springs, those of Beesley actioned sidelocks and the Dickson Round Action equal the price of a fine condition used Perazzi MX8.

Stereotypes and anomalies is perhaps apt for a situation where SXSs has stopped developing. Ideally we should be able to get a modern SXS with the feel and handling of a best gun, minus the luxuries, at prices which are as affordable today as they were in the early 1900s.

Best guns were always costly. Yes, but they were affordable. I wrote about this before but it bears repeating. A Royal Navy captain earning 450 pound annually could afford a 100 pound best gun in 1920. Today the same gun, (Stereotpye?) made using cost cutting CNC machines, costs more than the total annual income of a captain (Anomaly?).

Nice explanation of Hook's Law, Dewey.

It's in the manufacture of springs that the statistical evidence of failure is most observed. Coil springs are easier to make, more consistent in result, and thus cheaper, than v-springs.
It's prudent for a maker to choose an item that has a much lower likelihood of failure during destructive cycling tests.

You can buy boxes of springs guaranteed for many millions of cycles for a fraction of the cost of a box of v springs. It's just a more advanced, standardized technology.

I purposely leave out every other reason why another type of spring might be chosen or used other than dependability.
Money flowed into manufacturing coil springs, not as much into v springs.
One of our job shops makes us coil springs to spec in a couple hours. And that includes their runners time back and forth.

In one machine shop I worked in some years back we had a manually operated coil spring winder. A piece of wire was fed through adjustable rollers for size & spacing etc. Once adjusted you could then crank out a continuous spring limited in length only by the length of wire you were feeding it. I made a few springs on this implement. By adjustment you could make either a compression or expansion spring. As I see it the action of a coil spring is probably a combination of beam & torion but more beam than torsion. nothing wrong what-so-ever with a good coil spring but I am shooting shotguns well over 100 yrs old with their original v springs still going strong, obviously there wasn't much wrong with them either. I think it boiled down primarily to a matter of "Economy". The coi is as stated cheaper to build. I have noted over the years that when some method provides a suitable result with better Economy, It seems to be immediately promoted as having Far Superior qualities, though that is not always totally true.

Coil springs are very simple by nature. Some v springs, with legs, arms, hooks and rollers attached or as part of their original design are very complex machines. I know it's a bit of an over statement that you reach into a bin for a coil spring and open up the entire shop for some v springs. But not by much. There are just no off the shelf v springs to speak of, so replacing them is a more major task by nature. The plus is that both types are extremely durable so replacing them is a very rare thing. And some designs just can not be done with coil springs. For those a v spring and that complete shop are a must. Also someone like Dewey to make it. Good thread as long as we are dealing with guns.

There's room in my world for outrageously complicated, difficult to make, difficult to maintain things. In fact I prefer it that way.

However, after shooting a Purdey 28, I swear to God it operated like a Baikal. Probably not the place for a Beeseley action. I thought I was breaking it in two after every shot.

PM me if I can be of any assistance. There is a small but growing group of Ideal enthusiasts. Don't want to divert the topic any more.

Mike

this thread caused me to pull out charles askin's book "modern shotguns and loads", first published in 1929...

very interesting evaluations of american shotguns and their makers...

according to askin's, a major advantage of coil springs is that they make guns easier to open and recock...

Ed, did you know they use coil springs in those semi-automatics that you'd like to see severely restricted in the U.S.?

But they use flat springs in the large capacity magazines that you would also like to see severely restricted. What conclusions can we draw from that?

ANTI-GUN POSTS by ED GOOD