Greg G Posted June 25, 2003 Share Posted June 25, 2003 Hi All, I must admit I am a bit of a lerker when it comes to forums but I have a question to ask. I have reduced the strength on the main spring in my stock Para P-16ltd to try and get a lower trigger weight, as the one supplied with the pistol was very stiff, this seems to have worked quite well and I'm pleased enough with the results. However, what are the full effects of doing this? I have not reduced the strength a great deal, there is still more than enough power in the hammer strike to set off the primers. I am assuming that reducing the main spring may also reduce the spring pressure keeping the pistol in battery when a round is fired. I am also assuming that this effect is very minor and will not effect the reliability, power factor of ammo etc. I have put 100 rounds through since lightening the spring and it has functioned properly. Link to comment Share on other sites More sharing options...
ErikW Posted June 26, 2003 Share Posted June 26, 2003 This reveals everything. BTW, it's also known as a hammer spring and a mainspring (without the space). Link to comment Share on other sites More sharing options...
Jack Suber Posted June 26, 2003 Share Posted June 26, 2003 Greg, It has been my experience that a lighter mainspring seems to reduce the "perceived" recoil of the pistol. I assume that this is due to the fact that a light spring puts less resistance on the slide when it is unlocking during recoil. If the there is less resistance on the slide coming back, then there will be less reaward force to cause the muzzle to rise. I have been using 15# mainsprings in my Paras and STIs for years without any problems (related to the springs). My assumption of the the reason the recoil seems lighter might be wrong, but I can tell a difference between a 19# and 15# mainspring when firing. Later. Jack Link to comment Share on other sites More sharing options...
Loves2Shoot Posted June 26, 2003 Share Posted June 26, 2003 It does reduce felt recoil in my experience also. You should have no problems if you stay above 17lbs, sometimes 15lbs don't always hit the primer hard enough, but if I could get one that worked well at 15lbs, I would use it in a heartbeat. Link to comment Share on other sites More sharing options...
BigDave Posted June 26, 2003 Share Posted June 26, 2003 I've been running a 15lb ISMI mainspring for over 1 year now. I also use Winchester SP primers. One thing it reduced was overcock pressure (I believe that is the term). Basically what I'm talking about is when after the hammer drops, the slide has that much less force to overcome by re-cocking the hammer. I also run a 12.5 lb recoil with no buffs. This setup has worked well for me. I believe it improved my sight tracking. PS - this is a slab sided SV 40 with Major PF loads Link to comment Share on other sites More sharing options...
Flexmoney Posted June 26, 2003 Share Posted June 26, 2003 I've been running...for over 1 year now. That reminds me...I need to do some yearly spring replacement. Link to comment Share on other sites More sharing options...
reneet Posted August 5, 2003 Share Posted August 5, 2003 2 mechanical effects of running a lighter mainspring... #1) Potentially Increase slide speed thereby causing feed problems from magazine spring not being able to keep up. Also related to this is a decrease in lock time. #2) Reduce force of strike to firing pin causing misfires (particularly with titanium firing pin and/or slightly high primers). I've personally run Wolff 15 # mainsprings in both my open and limited STI pistols using Winchester Small Rifle primers without any problems. Link to comment Share on other sites More sharing options...
TDean Posted August 6, 2003 Share Posted August 6, 2003 By the way, welcome to the forums Renee. Link to comment Share on other sites More sharing options...
mcoliver Posted August 6, 2003 Share Posted August 6, 2003 Hi guys. Just 3 q's: 1. When you swap out main springs, do you cut them down "to fit" like we do with recoil springs? Or do you just drop them in as is? If cut down, how do you fit it? 2. What are some common visual cues that your slide is unlocking too early? 3. I'm guessing with the same main spring, a more square FP stop will also retard slide cycling, right? Thanks all. Link to comment Share on other sites More sharing options...
Skywalker Posted August 6, 2003 Share Posted August 6, 2003 2. What are some common visual cues that your slide is unlocking too early? A smeared firing pin mark on the spent primer is usually a good clue of this. If you start seeing the firing pin mark that, instead of being nicely rounded, has a sort of scratch starting from centre and going outwards, this means the slide is unlocking before the firing pin has retracted. This same symptom could also be caused by other factors than early unlocking (e.g. worn out firing pin spring). In worst scenarios, along with smeared primers, you start getting bulged cases from pressure not contained by the chamber (i.e. the brass is getting out of the chamber before pressures have lowered to a safe level). Link to comment Share on other sites More sharing options...
mcoliver Posted August 6, 2003 Share Posted August 6, 2003 Thanks Sky. Something to watch out for since I'm slowly working my main spring strength down together with the recoil weight. Link to comment Share on other sites More sharing options...
Detlef Posted August 6, 2003 Share Posted August 6, 2003 how could I miss this in my forum: If the there is less resistance on the slide coming back, then there will be less reaward force to cause the muzzle to rise. Junk physics alert Junk physics alert No. Eventually, your slide will come to a stop and go forward again, right? So consider the case where you remove the mainspring. Slide will come back faster, hit the stop harder and the force at that instant will be larger (!) than with the spring installed! Force is the change in time of momentum, and since the main spring slows down the slide on the rearward path, but does not accelerate it on the forward path (like the recoil spring does) reducing its strength will increase the force at the rearward bounce! All this has been said before, but in my experience the two primary beneficial effects of reducing main spring strength are: 1. You get a lighter trigger release. 2. You can afford a lighter recoil spring, which many people (including myself) experience as "reduced felt recoil". --Detlef Link to comment Share on other sites More sharing options...
Duane Thomas Posted August 6, 2003 Share Posted August 6, 2003 The idea is that it takes less energy to cock the hammer, therefore less rearward energy imparted to the frame. Firing 170 pf .45 ammo with a 17-pound mainspring and a 12-pound recoil spring, I don't feel the slide traveling backward hard enough to add to recoil. Now, if I drop the recoil spring down to 11 pounds I can feel the slide hitting the Shok Buff as the end of its stroke and that does add a really nasty "secondary recoil impulse" effect. Back up to a 12-pounder and that goes away. Link to comment Share on other sites More sharing options...
mcoliver Posted August 7, 2003 Share Posted August 7, 2003 Thanks guys. So my guess about the effect of rounding-off the bottom of the firing pin stop has minimal (or no) effect, huh? Link to comment Share on other sites More sharing options...
Detlef Posted August 7, 2003 Share Posted August 7, 2003 Duane, 1. wow, you can feel the difference between a 12 and 11 lb recoil spring? My spring scale often can't (some labelled "11 lb" are stronger than some labbelled "12 lb")... You're ahead of me.... 2. "rearward energy" is a junk physics term, energy has no direction, momentum has... --Detlef Link to comment Share on other sites More sharing options...
wide45 Posted August 7, 2003 Share Posted August 7, 2003 I use a 12.5lb ISMI. Feels soft. Tried an 11lb ISMI. Got a sharp smack feeling on every shot. Assumed it was the slide hitting the frame. No matter, the 12.5 works nice for me. Its very likely that the springs don't clock in at exactly 12.5lb, or 11lb. , but that was not the point. Link to comment Share on other sites More sharing options...
Duane Thomas Posted August 7, 2003 Share Posted August 7, 2003 It's all tooooooo complicated for me! <sound of head exploding> All I know is what the gun feels like in my hands. Link to comment Share on other sites More sharing options...
Detlef Posted August 8, 2003 Share Posted August 8, 2003 Duane, what it feels like matters. But when I do this kind of test, I make sure that I am not fooling myself by having a friend change the springs and not tell me what's in the gun. Such *blind testing* has opened my eyes to what I really feel as opposed to what I thought I should feel! And 11 lb vs. 12 lb recoil spring is a complete impossibility for me to feel the difference ... --Detlef Link to comment Share on other sites More sharing options...
STIshooter Posted February 7, 2004 Share Posted February 7, 2004 I'm just starting to experiment with different spring weights. A friend (GM <I bow before thee!>) recommended the ISMI 15 or 17lb mainspring combined with a LIMCAT Extra Long Firing Pin to prevent against light primer strikes. Will the extended firing pin combined with the faster unlock time exagerate the problem of firing pin drag on the primer? BTW: I'm shooting an .40 Edge with a Recoil Master and 170pf loads. Link to comment Share on other sites More sharing options...
ErikW Posted February 8, 2004 Share Posted February 8, 2004 STIshooter, no. I use the same components mentioned in Edge-like guns at 170+ PF. Never had any drag marks. Link to comment Share on other sites More sharing options...
Nate Posted February 8, 2004 Share Posted February 8, 2004 This seems like a good place for a slight thread drift. I bought a used SV with a mainspring that is a flat coiled spring. It has a very light feel on cocking but sets everything off. I have not found any like it. Any body know who makes them? Nate Link to comment Share on other sites More sharing options...
Rufus The Bum Posted February 9, 2004 Share Posted February 9, 2004 One thing I learned many years ago is not to play with springs in order to get a light trigger pull. Nowadays, my gunsmith does my trigger jobs and puts in a 19lb ISMI Mainspring per my request, there is NO DIFFERENCE. You can get a 2.5 lb trigger pull with that stiff a mainspring. Don't sacrifice reliablity for a light trigger pull. Link to comment Share on other sites More sharing options...
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