"Stiff" versus "long" recoil springs

[MAXM]

This is a "spin-off" of my previous post.

I thinf to be safe if I say that I can obtain the same spring "strength" with a short, thick-wired recoil spring and a longer. thinner-wired one.

You can see from my post "Springs (and my mind) confusion" that I received from a well known manufacturer two different recoil springs for 5" 45 ACP Colt 1911, both rated 15 lbs.

The first one measured 167 millimeters in length, had 35 coils, 1.08 millimeter wire thickness, 10.53 outer diameter.

The second one: in order, 158; 32 1/2; 1.14; 10.68.

Two very different springs, with the same rating!

Now, I have two questions:

1) assuming manufacturer's rating was correct, and the two springs have the same 15 lbs "strength", wich is the best for a carry gun to be used with 200 LSWC target loads, and 230 FMJ RN - 850 fps defense loads? And, most important to clear my mind's mud, what's the difference from a short, stiff recoil spring and a long, "softer" one?

2) assuming manufacturer's rating was wrong. wich of the two springs has the higher strength?

Thanks, Maxm

[EricW]

You're missing the point, however. A spring is trimmed to fit your gun so that it doesn't bind when the slide is in the full rearward position. You can't just stuff in a longer spring generally, because it will bind on itself before the slide has reached full travel - hence the need for different spring weights.

Yes, your are correct in your observation of Hooke's law that:

F = k*x

But, the 'x' is generally a fixed measurement. You can get away with a little less length, but more is usually a bad plan.

[MAXM]

Eric,

many thanks for your immediate reply, but could detail it better to me (I' not a smart one).

Please take note that in my Colt 1991 5" 45 ACP I can use equally well the 167 as the 158 millimeters long springs, without any spring binding.

I'm trying to understand why two so phisically different springs can have the same lbs rate, at what difference in performance they can delivery.

Maxm

[EricW]

Personally, I don't think spring engineering/science is really important as long as they work. You could while away your life fiddling with springs. Most people here run Wolf or ISMI springs and are happy. Those that like variable spring weights have gone to the Sprinco or STI Recoilmaster setups.

There should be a huge wealth of info about those here in the springs forum.

[.40AET]

The "Best" spring for any particular gun really comes down to two things.

A. What makes the gun function 100% all of the time.

B. What feels the best for the individual who is shooting the gun.

Find 3 or 4 springs that function 100%, then pick the one that feels the best in your hand. The physics of springs is interesting, but I would rather spend my free time reloading.

[mcoliver]

Get one spring in the color you like. Install it. Check for binding or early collapse. Check for gun function & reliability. If everyting's good, start shooting and forget about the spring until the next several thousand rounds.

[MAXM]

DETLEF, where are you?

[DogmaDog]

Alright,

You mentioned me by name, so I'll respond with what "expertise" I can.

Hopefully you've read this post by me:

http://www.brianenos.com/forums/index.php?...ndpost&p=116583

If not, that should help.

For the two springs you mention, it sounds like the shorter one with thicker wire probably has a higher spring constant, but will be compressed a shorter distance when installed in your gun. So both springs may in fact exert the same 15lb of force when the slide is opened, while the shorter one will exert a little less force when the slide is closed.

My guess is you won't notice any difference between those two springs. In my .45 I've run everything from 10 lb to 16 lb springs. I have to drop to 10 lb to get reliable functioning with my wimpy 125 pf (if that)155gr steel load. One time I forgot to take the 10 lb out and replace it with the 14 lb I used for IPSC major loads. I fired about 500 rounds before I remembered, and didn't perceive any difference.

One problem we have with tweaking our guns is that everything we change is over a very narrow range of possibilities--you might be able to vary your spring weight over a factor of 2 (say try a 10 lb or a 20 lb spring, and either would work), but you usually can't get even that much variation in other areas--you might be able to increase or decrease the weight of your gun by 10%, or change the weight of your bullets by 25%, or vary your powder charge by 20%--all of these are pretty small changes, and it's hard to make any difinitive measurements that would tell you what's "better" or "worse" .

With springs, try several. Shoot enough to ensure your gun functions reliably (I'd be surprised if those 15 pounders didn't work). Then if you feel, or think you feel, a difference between springs of different weights, pick the one you like better, and stick with it.

I use 14 lb spring in my .45, and a 12.5lb in my .40, for major PF loads.

DogmaDog

[Detlef]

MAXM,

I'll just state again what I said in the original thread: If you're really interested (and I never was...), build yourself a spring gauge to test these things. Yes, a longer spring might well give you the same counterforce at the same x as a shorter one (probably though, because the *k* is not really constant from zero compression to where you compress it to when you install it in your gun).

A friend of mine built a gauge and says the labeled ratings are nothing but a rough guide...

--Detlef

[MAXM]

I asked to the manufacturer. He said (these are his exact words) that the second 15 lbs spring (the shorter and stiffer) "is current production and has a slightly higher linear compression rate than the first. This means that the spring will "work" or disburse more energy during its compression stroke".