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Recoil spring weight and Sight tracking


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I've been playing with the recoil spring and testing my splits in my M&P pro and noticed that it is easier for me to track the sights with a heavier recoil spring (15 vs 13lb).

My splits on were identical or slightly faster with the 15 lb spring on targets out to 15 yards, but much better (faster and more accurate groups) at 25 yards.

I liked the feel of the 13 and it felt faster since the sights returned to target quickly (although usually a little high), the 15 feels slower but i can track the sight better throughout recoil (maybe why it feels slower).

Anyone else notice this?

Edited by bthoefer
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  • 4 weeks later...

I noticed this as well last night while shooting. I shot great with a 15#, switched in a 13# and my groups started to open up and I started missing. (Shooting 4" steel plates at 15-25 yds). I also felt like I was a bit slower on follow ups and didn't feel like I could track the sights as well. Needless to say I will be switching back to the 15#. Why change something that works great.

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I've noticed an improvement in time and accuracy (reliability, too) since going back to the original captured guide rod & spring in my M&P 9L. I was using a SSS tungsten guide rod and 13 or 15 lb spring. Go figure?

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The recoil spring you use should really depend on how the front sight is returning post shot. Your comment of "although usually a little high" tells you that the 13lb recoil spring is too light. The goal in tuning the recoil spring weight is to have the front sight lift up out of the notch during recoil, then come straight back down to an aligned state post shot. What weight recoil spring this ends up being greatly depends on how you grip the gun and how firm your grip is. The best way to figure out which recoil spring to use is to do exactly what you did. Test each one out and see which spring produces the best return of the front sight post shot.

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Cha-Lee

I feel like both recoil springs return the sights about the same. The 13lb returns the front sight slightly high, but the 15lb dips a little when the slide returns to battery. They are both off just a little bit but not much.

I've settled on the 15 for now because of a few failures to go into battery with the 13 when the gun is dirty (around 1200 rounds since cleaning). I prefer the feel of the 13 but don't want to give up the reliability. I also think the gun groups more consistently with the 15. I think the 13 is just right at the edge of being too light and isn't 100% consistent in lockup.

I'm using ismi springs but will probably try a wolf 12 and 14 lb eventually. It seems like the consensus is they run heavier compared to the ismi springs.

I might also try cutting a coil off an ismi 15lb spring to get a 14lb ismi.

Edited by bthoefer
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Its best to error on the "heavy" side on striker fired guns because the striker spring is fighting against the recoil spring when the gun is cocked. If you have too light of a recoil spring you will have a weak and inconsistent lockup when the gun is cocked. This issue gets exponentially worse when you shoot one handed. Cutting coils off of springs really does not change the overall fully compressed spring tension. It does drastically change the slightly compressed spring tension. If you cut coils off of the 15lb recoil spring it will probably result is a weaker and inconsistent lockup but still produce the same felt recoil as a standard 15lb spring. This is at least what I have experienced in my testing.

The next time you go out to test recoil springs, try the 13lb spring again but consciously grip the gun harder. My bet is that the front sight will return exactly how you want it with a slightly firmer grip. I have several M&P's that feed and lock up properly with 13lb recoil springs. But all of these have a the reduced power APEX striker spring, which improves the lockup. That and I grip the crap out of the gun while shooting. Another option is to use a Tungsten guide rod as that will help reduce the total amount of muzzle flip due to the added weight in the frame.

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Thanks Cha Lee,

What got me thinking about cutting a coil is that the 13 lb recoil springs are noticeably shorter than the 15 lb. The new; never installed ,13 is a good 1.5 - 2 coils shorter than the 15 with a couple months use on it.

I'll try focusing on my grip next round. I feel like I grip the gun pretty hard, but I'm not exactly a big guy :)

Edited by bthoefer
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Yep no failures with the 15lb.

Sometimes I can feel the slide go into battery when I pull the trigger but not all the time.

I'm sure that my thumb isn't riding the slide, because when I do I can feel it slowing the slide.

I can easily replicate the issue with the empty gun. I know it's not a bad spring, I have tried 3 different ones. One was good for a little I've 1000 rounds before it started having issues, the other 2 have the same issue brand new.

I already have the apex striker spring installed after the issue started and it didn't stop it.

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Tried the 13 ismi recoil spring in my M&P Pro 5" had multiple failures to go into full battery, went back to the stock 16lb. ? factory spring no problems. I believe that the shorter 13 is the reason, how much shorter than stock is your 15???

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I'm not sure how much shorter than stock the 15 lb is since I haven't taken the stock spring off the captured guide rod.

I know that the 15 lb is almost 2 coils shorter than the 15.

I don't remember the first (the one that worked for a little over 1000 rounds before causing issues) 13lb recoil spring being shorter but I wasn't paying attention when I put it in.

I do think a 13 lb spring with the same length as the 15 would work, since it would be pre loaded (compressed) more and exerting more force as the slide came into battery. I believe that the spring rate is weighed at it's fully compressed state so something like this could be possible.

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  • 2 weeks later...

I've been playing with the recoil spring and testing my splits in my M&P pro and noticed that it is easier for me to track the sights with a heavier recoil spring (15 vs 13lb).

My splits on were identical or slightly faster with the 15 lb spring on targets out to 15 yards, but much better (faster and more accurate groups) at 25 yards.

I liked the feel of the 13 and it felt faster since the sights returned to target quickly (although usually a little high), the 15 feels slower but i can track the sight better throughout recoil (maybe why it feels slower).

Anyone else notice this?

I noticed the same thing today. A 15# spring tracked better on Bill Drills than the 13# spring I was using. The groups were faster and tighter at 25 yards also. Interesting...

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  • 5 weeks later...

I haven't tried wolf springs, I posted in the springs forum about them but got no responses. I might try wolf springs to see if the gun will run with a lighter spring. It seems like the wolf springs run heavier than ismi springs so I'll probably try a 12 and 14.

Wolf lists the stock S&W spring as 15lbs , while ISMI lists it as 16lbs so I think they measure differently (full compression vs. slide travel).

Edited by bthoefer
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