Is there a way to determine spring "weight"?

[Lou_NC]

I have some spring kits for my S&W revolvers, and have decided that I'm going to stick with factory mainsprings and use only reduced-power trigger return springs as I perform my action work (polishing) on these revolvers.

I've always been careful about keeping the aftermarket spring kits in their original bags and marking which ones have been substituted into which revolvers by serial #. But I just started wondering - is it possible to pick up a random trigger return spring of unknown "weight" and determine whether it's a 12# or 14# etc, by measuring it somehow, either using calipers to measure length, count coils, a combination of both, etc?

Some of my spring kits are from different manufacturers (Wolff, Bullseye), so I'm wondering if it's even possible to correlate spring weight to physical dimensions, and if there's any consistency among different manufacturers?

I definitely plan to keep things straight with the springs I have, but I can't help but wonder if there's a way to "characterize" a random spring if I come across one?

Thanks,
Lou

 

[armorer951]

One of the forum members, 5shot, posted this a few months ago.........

http://smith-wessonforum.com/s-w-smithing/264344-rebound-springs.html

 

[varmint243]

I used spring rate testers for valve springs and suspension springs when I worked in a race shop.
You measure the amount of change per inch of compression.
So if you put preload on a spring pushing against a scale, zero the scale, and then compress it one inch, the reading on the scale would be the spring rate.
Note that spring rate and preload are two different things.
The spring rate does not change as you compress it.
The first inch and the third in of compression will change the same amount.
Only the preload would change as you squeeze the spring.
Google valve spring tester and you will get the idea.
there are several brands/models that do a similar thing
Wire length and wire diameter affect spring rate.
They type of spring steel would also have an effect.
When a gunsmith clips a coil or two he lessens the preload and increases the spring rate at the same time.
The feeling to the shooter is a lighter trigger, but that is not exactly what happened.
Throw all that out the window when you are talking about variable rate springs.

 

[hotrod150]

I'm sort of surprised (and disappointed) that Wolff (and probably Apex & Wilson too) don't color code their springs. I too am very careful to keep track of which spring is which when messing with them, but it's kind of a PITA.

 

[flintsghost]

Some where on the internet is an article about building a spring tester to check the weight of 1911 recoil springs. It was simple enough but I didn't keep it book marked and lost it over the years. Searching may bring it up. A similar device scaled to do the springs you're interested in should work.

 

[exSun]

One way to re-phrase the question would be to ask if Smith & Wesson have a standard procedure used to measure the weights of various springs, and if so, can someone tell us what it is?

 

[chief38]

While I have never tried it, has anybody ever weighed the trigger while returning to its resting position (from the full squeezed position) with a trigger weight scale? Don't know if that will work, but I would THINK it should if it were done without the mainspring installed. My personal scale (RCBS) is only calibrated to 8 pounds but you would obviously need one calibrated to 16 pounds or slightly more.