Recoil Springs???

S

Sigma 40 Blaster

New member
All,

Looking for a little advice about modifying my sw40ve (sigma). I have already done the trigger job shown on other sites to get the pull from around 12 to 5-7 lbs. Works great and reliable after 1000 rounds through it...

Now my next project is to replace the recoil spring...I didn't even think about this until I saw them listed on midway. I'm no physics major but it seems as if a lighter spring would make you feel less kick (felt recoil) BUT it would kick the slide back with greater velocity...

Am I even on the right track with my comprehension of how these things work? If so what are the inherent dangers of going from a 15 lb. spring to say a 10 lb spring???

I am not a big fan of mod'ing my primary CCW weapon but if I can find a reliable way to improve it's performance and my ability to shoot it I'm game. Please don't advise me to buy a different gun, this one is fine, just looking for a way to optimize my experience a bit.
 
You have it backward. A heavy spring exerts less felt recoil because it distributes a larger portion of the recoil over the compression length of the spring. When you lighten the spring, it absorbs a smaller portion of the total recoil by the time it is fully compressed, and what remains is dumped very suddenly into your hand when the slide bangs into whatever it stops against in the frame. That creates a shock. The portion absorbed by the spring is graduated, rather than sharp, and the more the spring absorbs, the spongier the recoil feels.

I don't own a copy of your gun, but have done the recoil spring thing in 1911's for many years. If you match a spring to your load, such that the slide just barely touches down in counter-battery, that has the lightest feel (no shock). It also has compromised reliability because if you loosen your grip, the whole gun moves back a little, so the spring has even less to absorb, and the slide never makes it fully into counter-battery and may not pick up the next round.

For a practical gun, the only reason to lighten the recoil spring is to promote function with reduced power target loads or to correct feed failures due to a weak grip. You also don't want to go too far in the other direction because too stiff a spring makes it harder to rack the slide, and may give you the reliability issue I mentioned in the last paragraph, and also may not work as well with some ammo as others.

To optimize a spring choice, I would use the heaviest spring consistent with firing ammo you will use for the purpose and that works with off-hand firing from your weak hand or any other test compromise position you can come up with. Stiffest spring consistent with weakest grip and still functions with all ammo you might have to use. Those are the criteria.
 
Thanks, so I need to find a slightly heavier spring and find the weight that will still feed ammo when shooting left hand only...I never would have thought about that.

Thanks again.
 
Springs are engineered at the factory for optimal performance with a wide variety of loads. The Germans even go so far as to graph the pressure curve on a spring to ensure that there's no spikes in the spring's performance.

Changing the spring makes it specific for certain loads. You have to test, re-test and constantly test the gun to ensure reliability. That's exactly why law enforcement agencies don't allow after-market springs or magazines (at least the armorers and range masters I've met told me) for duty wear.

Aftermarket products are a lot of marketing hype. I doubt if they do half the tests that the factory does. Their products are fine for sporting purposes, but not for self-defense where maximum reliability is the priority.
 
4v50Gary...In the past few days I've been thinking about what you just wrote...reliability for my primary CCW is paramount. The trigger mod I did increased the number of rounds I can accurately shoot in a range session to about 80...instead of trying to stop the recoil I'm thinking I just need to focus on bringing it back on target, my time on double taps is WAY high right now

I need to stop watching those stupid USPSA videos where guys are shooting .45's like .22's.

Or I just need to get a heavier gun to compete in the USPSA production class...
 
Sigma 40 - You're initial impression was actullay on target to some degree. The lighter the spring, the less it will push on the frame/you during recoil. This will result in the LEAST overall rearward impulse but (as Unclenick pointed out) you will get a larger "sudden" impulse when the slide hits the frame. The difference can be hard to perceive, but with careful comparison one may find the lighter recoil spring may feel a little snappier but will shoot a little flatter. The heavy recoil spring slows the slide a bit which means the recoil spring is pushing on you slightly longer. Also, when the slide closes, it is the recoil spring pushing against the frame/you that helps it along. The shooter feels this to some degree as the slide closes and (in reverse) when the slide slams into battery. This is primarily why the heavier spring doesn't shoot as flat (there is greater push/slam going on from the heavier spring). For a defense weapon, it would make sense to stay with the factory spring unless there is a reliabilty problem/reason not to.
 
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