Overhaul an S & W 9MM-when?

gifbohane

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I have a 15 year old S & W 9MM (M&P) that has about 10,000 rounds through it. I am wondering if I should send it to S & W or a local guy for new springs and whatever to keep it functioning properly.

It is ejecting a little short nowadays but seems OK otherwise.

Anything I should look for in the wear and tear department? I do have a new barrel waiting.
 
I've done the spring kit upgrade for my buddy's M&P9. It's all thats needed and intermediate in difficulty.
I have a 15 year old S & W 9MM (M&P) that has about 10,000 rounds through it. I am wondering if I should send it to S & W or a local guy for new springs and whatever to keep it functioning properly.

It is ejecting a little short nowadays but seems OK otherwise.

Anything I should look for in the wear and tear department? I do have a new barrel waiting.
 
At some point it is good to replace the mainspring. Mainsprings loose their strength. A strong mainspring provides strong ignition, and this cannot be overstated for function reliability. Mainspring and recoil spring strength are hugely important in the timing of the mechanism. The slide has to push down the mainspring, a weak mainspring creates a high slide speed on recoil. So does a weak recoil spring.

I have found the importance of recoil/main spring strength in my 1968 22lr M46 Smith and Wesson, and my 1962 ish Ruger MK1.

My 1968 M46, all original springs, was a malfunction junction. First thing that helped was replacing the recoil spring with a Wolff "factory"

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as you can see the original recoil spring had taken a set, and that caused timing issues, such as stove piping. I replaced the recoil springs in my M46 and M41. I carried that used M41 spring in my kit, and at one indoor match, a fellow shooter with a Godawful old M41 was having failures to feed/eject. His recoil spring was shorter than my used M41 spring. When we installed my used spring, his pistol was able to function. Since then, I keep a new "factory" Wolff in the box, just in case.

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Another problem, the more rounds downrange, the more unreliable both the M46 and my 1988 M41 became in feed, extraction, ignition. Called S&W they were out of OEM factory mainsprings. Numrich claimed to have new ones. Ordered a few.

The Numrich springs looked like someone cut them from coil wire with a cutter. All of different length, the ends sharp, not nice and ground, like the factory springs. However, put the longest one in the M46 and it worked for a time. Then back to stove pipes and failures to ignite.

Called S&W again, still out of mainsprings. But there were vendors on ebay claiming to have new OEM mainsprings, and I purchased two.

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In comparison, the worn Numrich spring was short, and I could tell from the effort it took to cock the hammer, that the "new" OEM was considerably stronger. I also replaced the 1988 M41 mainspring, and the new one was stiffer. Which is all to the good.

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Just as the recoil spring, the mainspring has an effect on the timing of the action. The slide has to push down the hammer. For proper timing, that mainspring has to be factory strong.

Something else, the "bolt", part number “6508" (firing pin block) in the slide fills with oil. I consider the elbow the drip point, so I over lubricate: bite me. However, I found mine filled with oil, and that has to reduce the velocity of the firing pin impact on the rim. I removed the bolt from the M46, found it swimming in oil. cleaned everything out, and re installed. Now after a match, I am in the habit of blowing the firing pin channel out with compressed air. You have to push the firing pin forward, as when it is in normal rearward position, it seems to be a gas block. So I push it forward with a chop stick, and blow the channel out from the front. I hope it improves function. At least I am blowing the rat's nests, and spider webs out of the firing pin channel!

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Recently replace the recoil spring and mainspring housing in my Ruger Mk1. What was also a malfunction junction is now perking reliably (as reliable as a 22lr pistol can be) with my ammunition.

These 22lr incidents have made me realize that what is good for rimfire, is also good for centerfire.

With my 1911's, I have no problem removing the firing pin and spring, and cleaning out the channel. Others have had misfires in cold weather due to oil/etc in the 1911 firing pin channel. Other designs are much more difficult to remove the firing pin, for those designs, I think it smart to blow out the firing pin channel when you think of it. When I blow out the channel on my M92 FS Beretta, what comes out is black oil. Removing that oil before it evaporates into a gum is good for function. You might have to push the firing pin forward with a chop stick to blow it out from the front. I found on the M46/M41 and Beretta that the firing pin will act as a gas block until it is pushed forward.

With any semi auto pistol, keep the recoil springs and mainsprings new. Don't think 20 year, 50 year old springs have the same strength as new springs. They don't. No semi auto pistol has the ignition energy of a rifle. Powder combustion is hugely dependent on how much energy and flame comes out of that primer. Weak primer flame, weak powder combustion. Primer combustion is complicated, but for you, weak ignition system, weak primer combustion. Period, end of story.
 
Can anyone advise the best place to buy the replacement parts...or just go to S $ W?
 
I have been using both Wolff & ISMI flat springs for quite some time.
I fabricated an accessory to the digital force gauge to measure / calibrate recoil springs etc. and was surprised to find
that some new springs were out of wt specification by 1-3+ pounds, I presumed it was a incorrect packaging situation.
Wolff recoil springs come with extra striker springs as a bonus! So, check them when you can.
Just for fun, I authored a comprehensive technical Manual on the M&P9 platform.
That is all.

IMG_5276.jpg IMG_5998.JPG IMG_5277.jpg IMG_9332Gunsmith Digital Force Gauge Measurement Pistol Recoil Guide Rod Spring Rates MJD 11.1...jpg IMG_9334Gunsmith Digital Force Gauge Measurement Pistol Recoil Guide Rod Spring Rates MJD 11.1...jpg IMG_9328Gunsmith Digital Force Gauge Measurement Pistol Recoil Guide Rod Spring Rates MJD 11.1...jpg IMG_9259A copy.jpg
Screenshot 2025-02-05 at 10.44.17 PM.png
 
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Try Midwest Gun Works.
Ive had great luck with these guys when I lost the plunger for my M&P that goes in the striker.

As far as springs? Im over 15k on my original springs on my Gen1 5" M&P Pro. It still shoots fine and isnt beating the gun up. Should I replace them? Probably. Is it a huge concern? Nope.
 
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