MAXM Posted December 18, 2003 Share Posted December 18, 2003 I know my question(s) has been exploited many many times, but even after reading all previous threads I am confused . Could someone patiently explain me, in easy terms, the practical differences from spring "rate" and "strength"? If I clip some coils I don't change rate, but I reduce the spring total strength, right? Or not? And if Colt and other manufacturers puts on their 5" 45 ACP 1911 pistols 16 lbs recoil springs, and many gunsmiths prefere the 18.5 poundage, why I read here to choose much lighter recoil springs? I can understand this for raceguns, but I'm in doubt for my carry gun, that with 16lbs spring functions very well and ejects cases quite smartly. I ask these questions without the smallest hint of polemics, and only to take profit of your experience. Many many thanks, and please accept my excuse for my bad english, and my best wishes to all forum members of a Merry Christmas and an Happy Shooting New Year. MAXM Link to comment Share on other sites More sharing options...
Flexmoney Posted December 18, 2003 Share Posted December 18, 2003 I'll give it a shot...though I am likely wrong. Any spring is a piece of steel...and if you un-coil it, you'd have a steel "bar". The size of the bar effects how much spring it has. When I think of "rate", I think of how much "spring" you get per inch of spring. The competition shooters go with a lighter spring for feel and performance. You usually need a pretty well built gun and a lot of confidence in the ammo you feed it to be able to get by with going light. Factory built...and carry...guns are often better served with a heavier than compeition recoil spring. Link to comment Share on other sites More sharing options...
Sixgun Posted December 18, 2003 Share Posted December 18, 2003 MAXM, There is some good info here: http://www.gunsprings.com/Resources/FAQ.htm Ray C. P.S. For your carry gun, if what you are using now is 100% reliable, I'd be very hesitant to change. Just my opinion. Link to comment Share on other sites More sharing options...
DogmaDog Posted December 22, 2003 Share Posted December 22, 2003 The recoil spring exerts a force between the frame and the slide. The force is described by the equation f = kx, where f is the force, x is the length of compression of the spring, and k is a constant expressed as pounds per inch--the spring rate. A 16 lb spring is one that exerts 16 lbs of force when the slide is fully retracted. When that spring is just sitting on the table, it exerts 0 force because x, the length of compression is 0. If we compress the length of the spring by one inch, the spring will exert a force equal to k. If you compress the spring another inch, the force will be 2k. When you install the spring in the gun, it is compressed even when the slide is closed. I don't know the exact lengths, but suppose you have to compress the spring by 2 inches to get it into the gun, and that the slide retracts another 2" during cycling. We know that when fully compressed, the spring exerts 16 lbs of force, and we now know it is compressed by 4", so we can solve the equation f (16) = k x (4"). k, the spring rate, is 4 lb per inch. The spring also exerts 8 lb of force when the slide is in battery. Now, if I cut one inch (when uncompressed) of coils off the end of the spring, I'll still have a spring with k = 4, but I'll only have to compress it by 1" to get it into the gun, and it will only compress by a total of 3" when the slide is retracted. Now the force is only 12 lb when the slide is retracted, and 4lb when in battery. Note that if we cut coils, we increase the RATIO between the force exerted at maximum slide travel to the force exerte in battery, and we decrease the amount of force exerted at either end. If we just used a lighter spring, the ratio of forces would stay the same, but the force at either end would be less. A variable rate spring doesn't have a constant k. For small values of x, k is small, and as x increases, k increases. I'm not sure how this is achieved mechanically (changing diameter wire, or changing coil pitch, perhaps?), but it has the effect of increasing the ratio between force exerted when open, and force when closed--just like cutting coils on a constant spring. I haven't worked out exactly WHY USPSA competitors prefer lighter springs. I think what's happening is that with a lighter spring, you don't feel as much recoil force during the early part of cycling, because the spring just isn't pushing hard on the frame. That force builds more quickly, though (because the slide moves rearward faster with a lighter spring), and the gun will actually complete its cycle faster if the slide actually hits the frame and bounces back. So a lighter spring has the effect of delaying (by maybe 0.01 or 0.02 s) and sharpening the peak recoil impulse felt by the shooter. It may be that us racegunners are just faster if the recoil comes all at once rather than as a prolonged pulse. For any gun (carry or competition), you need a spring that allows the gun to function reliably, so that will constrain the range of spring weights you can use. Heavier springs may improve feeding reliability, since they can push bullets out of the magazine with more force, so gunsmiths may recommend them for that, in carry guns. Clear as mud??? DogmaDog Link to comment Share on other sites More sharing options...
Gun Geek Posted December 23, 2003 Share Posted December 23, 2003 Right on Dog! Link to comment Share on other sites More sharing options...
Run n Gun Posted December 23, 2003 Share Posted December 23, 2003 Not such a dumb question, it took three guys and a course in physics to answer it! Welcome to the forum. I’m sorry; I don’t know how to say “Merry Christmas and Happy New Year” back to you in Portuguese. Ed Link to comment Share on other sites More sharing options...
SiG Lady Posted December 23, 2003 Share Posted December 23, 2003 "Much appreciated post!!", she says. Link to comment Share on other sites More sharing options...
Shipster Posted December 23, 2003 Share Posted December 23, 2003 Way to go Dog! Even I understood that. And you got SiG Lady talking in the third person. Way cool. Link to comment Share on other sites More sharing options...
BrazilianShooter Posted December 23, 2003 Share Posted December 23, 2003 I’m sorry; I don’t know how to say “Merry Christmas and Happy New Year” back to you in Portuguese. Hey ED just say "Feliz Natal e Prospero Ano Novo" Hey Dog that was a lesson of Springs, thanks Link to comment Share on other sites More sharing options...
Run n Gun Posted December 24, 2003 Share Posted December 24, 2003 Thanks BrazilianShooter! ...and, Feliz Natal e Prospero Ano Novo to you both! Ed Link to comment Share on other sites More sharing options...
SiG Lady Posted December 24, 2003 Share Posted December 24, 2003 I was told that a variable rate spring was a matter of changing coil pitch....... Link to comment Share on other sites More sharing options...
DogmaDog Posted December 24, 2003 Share Posted December 24, 2003 Hey all, Thanks for your compliments. I'm glad I could write something coherent. Sig, I think you're right--I just took some measurements on a variable spring, and found the distance between coils varies along its length. I suppose it would be hard to make a wire with a changing diameter along its length. Also, I said earlier that cutting coils and using a variable spring both had the effect of increasing the ratio between spring force in battery and at max rearward travel of the slide. That is true, but cutting coils does NOT make a constant rate spring into a variable rate spring. As to why one would prefer a variable rate over a constant rate, the only thing I've been told is that a variable rate allows the pistol to unlock faster. I don't know why that is desirable, though. Merry Christmas/Happy Hannukah/Sunny Solstice to all! DogmaDog Link to comment Share on other sites More sharing options...
MAXM Posted December 28, 2003 Author Share Posted December 28, 2003 MAny thanks to all for your kind reply. DogmaDog, you are really great in explaining difficult things!! (Just for completeness: I'm italian, not portuguese) Buon anno a tutti! (Happy new year to all you, guys). MAXM Link to comment Share on other sites More sharing options...
glockman30 Posted February 26, 2004 Share Posted February 26, 2004 Dog, I'm taking Physics at LSU, and your explanation sounds correct to me. Link to comment Share on other sites More sharing options...
DogmaDog Posted February 26, 2004 Share Posted February 26, 2004 Glockman, Ack! I really enjoyed physics, but physics class was a whole 'nother story. Good luck with that (my class was full of pre-meds who didn't want to study physics, and a cocky professor who didn't want to teach stupid pre-meds). You study at LSU, so do you ever get out to Gonzales to shoot on the 3rd Sunday of the month (that's the furthest west I go to shoot). Hope I'll see you there some time. DogmaDog Link to comment Share on other sites More sharing options...
scooterj Posted February 29, 2004 Share Posted February 29, 2004 Dog, everyone in SE LA shoots EAPS on 3rd Sunday. You need to skip the indoor match in Arabi on the 1st Sunday and take a ride to New Iberia. The best part is the seafood buffet at Landry's afterwards. Link to comment Share on other sites More sharing options...
Detlef Posted March 2, 2004 Share Posted March 2, 2004 sounds like PMable info. Closed. Link to comment Share on other sites More sharing options...
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