Slide lightning

[whoflungdo]

Has anyone lightnend their slide? Did you have to go to a lighter recoil spring? I have had 1.5 ozs taken out of my slide and think I should go lighter springs.

[Steve RA]

Try it first, see how you like it.

[a matt]

What kind of gun?

[whoflungdo]

M&P Pro 40. KKM Barrel, Tungsten guide rod, Apex FSS. Limited class gun

[TheBoss]

1.5 oz is a lot of slide weight taken out (approx 8%). Decreasing the recoil spring weight allows for faster slide operation during recoil. However, there is a trade off with ejecting the spent round and bottoming out the slide. When the slide is operating too fast FTEs will occur as the extractor cannot keep up with the slide speed. Too light on the recoil and the slide bottoms out and will eventually crack the slide.

I ran some numbers and it appears dropping to a 15# will get you close to the slide to recoil weight ratio.

I am in the same boat. I dropped my slide weight from the factory weight of 19.1 oz to 18.4 oz. The factory slide to recoil ratio is 13.4031 for a 16# recoil spring. If I drop to a 15# recoil spring I am at 13.0434.

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[CHA-LEE]

1.5 oz is a lot of slide weight taken out (approx 8%). Decreasing the recoil spring weight allows for faster slide operation during recoil. However, there is a trade off with ejecting the spent round and bottoming out the slide. When the slide is operating too fast FTEs will occur as the extractor cannot keep up with the slide speed. Too light on the recoil and the slide bottoms out and will eventually crack the slide.

I ran some numbers and it appears dropping to a 15# will get you close to the slide to recoil weight ratio.

I am in the same boat. I dropped my slide weight from the factory weight of 19.1 oz to 18.4 oz. The factory slide to recoil ratio is 13.4031 for a 16# recoil spring. If I drop to a 15# recoil spring I am at 13.0434.

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I have to disagree with your statements about the slide being too light would cause extraction or or slide bottoming out issues. The fact is this, regardless of slide weight or recoil spring weight the slide is going to come back super fast and bottom out against the frame. Thinking that you can eliminate the slide from bottoming out against the frame by using a stiffer recoil spring is completely unfounded. Semi Auto guns are designed so the slide does bottom out against the frame to provide a consistent and repeatable "Full Back" position for the slide. If you lighten the slide and start to have failure to extract issues that is an extraction problem, not a slight weight or cycle speed problem. The extractor is probably slipping off of the rim of the case due to being worn out or not set to the proper depth or the extractor spring is too weak. Increasing the slide cycle speed simply exposes extraction issues that already exist.

As far as slide weight verses recoil spring weight, which combo to use really depends on your grip strength. Lightening the slide weight will reduce the felt recoil and allow the slide to move faster because there is less mass to move back and forth. Using lighter recoil springs will also reduce the felt recoil and will slow down and lesson the force driving the slide back forward as it cycles. On an M&P the thing you have to watch out for is using a recoil spring that is too light because the recoil spring and the striker spring fight against one another when the gun is cocked. If the recoil spring is too light the striker spring will actually pull the gun out of battery when its cocked. Due to the recoil/striker spring fighting situation the lightest recoil spring you can get away with is usually an 11lb. If you want to use an 11lb recoil spring you should try running a reduced power striker spring to further reduce the "Pulling the slide out of battery" condition created when the gun is cocked.

Another thing to watch out for with running weak recoil springs is that your feeding may be negatively impacted, especially if you allow the gun to muzzle flip excessively. Since a lighter recoil spring has less mechanical leverage against the slide it will pick up the rounds with less force. If you let the gun muzzle flip excessively you take further energy out of the slide cycling process. A good example of this is jumping on a trampoline. If you jump then land on the trampoline with straight legs and locked knees all of your downward force gets preloaded into the springs and can be fully unloaded back through your body creating a solid jump. If you land with your knees bent and allow your knees to bend as you impact the trampoline a huge amount of your kinetic energy is lost by your bending knees and not much is transmitted to the springs, which results in less rebound force. The same kinetic energy loss is happening when you shoot an auto pistol and allow it to muzzle flip excessively.

[RWF]

on my limited gun i use sprinco with a extra coil on the sub spring and #14 recoil spring, on my open i use a #13. the wife uses a #15 spring.

all of these have lighten slides

these all M & P Pro's 9mm the limited PF is 130

the open is full power 124

[RWF]

the limited gun has been running for 4-6 years

[TheBoss]

I must correct an earlier post. My research has found, Varying the recoil spring weight does not affect cycle rate of the slide. Lightening the slide, lighter bullet weights and varying powder charge affects cycle rate.

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[TheBoss]

@Cha-lee

What i have found is slides operating too fast run into ejection failures due the extraction occurring while the case is still under pressure. This is why too much weight out of a slide is not a good idea.

Additionally, adjusting the recoil spring, from my observations, will not affect the cycle rate. Slide weight, bullet weight and powder charge affect cycle rate.

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[RWF]

the limited gun has been running for 4-6 years

do not any facts or data, but not a issue 9mm 147 PF130 just a quess but better than 7-8k rounds. the open gun trying to make a 11# spring work made a few out of battery shots, it really pisses you off when that happens.

[Akkid17]

I must be bass ackwards on my reasoning then. I had a lot of weight taken off my 5" 40 and it was kicking the muzzle up during rapid recoiling or for doubles or bill drills. I went all the way up to a 20 lb'er to get it back in line. Now the sights come to rest back on (or close enough) to original point of aim. I figured less reciprocating mass would make it so that all the inertia was dumped into the frame and the lighter spring would not have the force needed to return the slide with equal force for consistent follow ups therefore requiring a more powerful recoil spring. Maybe this just worked better for me? Thoughts?

Forgot to mention I don't have the final weight reduction but it was a 3/8th slot about 2"ish long on both sides of the slide. It now feels lighter then the 4.25" slide

Edited December 19, 2012 by Akkid17

[CHA-LEE]

I must be bass ackwards on my reasoning then. I had a lot of weight taken off my 5" 40 and it was kicking the muzzle up during rapid recoiling or for doubles or bill drills. I went all the way up to a 20 lb'er to get it back in line. Now the sights come to rest back on (or close enough) to original point of aim. I figured less reciprocating mass would make it so that all the inertia was dumped into the frame and the lighter spring would not have the force needed to return the slide with equal force for consistent follow ups therefore requiring a more powerful recoil spring. Maybe this just worked better for me? Thoughts?

Forgot to mention I don't have the final weight reduction but it was a 3/8th slot about 2"ish long on both sides of the slide. It now feels lighter then the 4.25" slide

There are four main variables that need to be balanced to one another.

(1) The Power Factor of the ammo being shot

(2) The grip pressure you are able to grip the gun with

(3) The total weight of the slide

(4) The spring tension of the recoil spring.

If one of these things is disproportionately out of balance with the rest you will have to use an equally disproportionate recovery.

In your case, it sounds like you are not gripping the gun hard enough to allow the lighter slide to snap back forward returning the sights to an aligned state post shot. You are artificially "Fixing" This by using a disproportionately heavy recoil spring. If you put the lighter recoil spring back in and simply gripped the gun harder it would produce the same on target hit results.

In my testing I have found that its best to figure out what weight recoil spring is best suited to my grip pressure and ammo PF to minimize maximum muzzle flip and felt recoil. From there I will observe how the front sight tracks post shot. If the front sight stays high then the recoil spring is too weak for my grip pressure or ammo PF. If the front sight dips low then comes back up post shot then the slide weight is too heavy and needs to be lightened. The Dip low then come back up can also be due to a recoil spring that is too strong.

In general, the stronger your grip pressure is the lighter the recoil spring and slide weight can be while still maintaining proper sight tracking. Since everyone has a different level of grip pressure and muzzle flip management there really isn't a "One setup works best for everyone". All you can do is test the different spring and slide weights and see which one works best for you.

From what you described, it sounds like your slide is too light for your grip pressure.

[Akkid17]

Haha, well if that's the case I'm SOA as far as the slide weight is concerned. Next range session I'll bring out some other springs and fool with the grip tension a bit and see what happens. In any case it will be good to try something different especially if it works out better for my shooting.