Reliability affected by heavier recoil springs?

[tcarp1911]

I have an M&P9 I decided to do a little it of experimenting on. I am curious to see if going from a 15 to a 17 pound recoil spring will affect anything, whether it be groups, POI, etc. I made sure the pistol had at least 500 rounds through it before trying this in case "breaking it in" could affect it.The pistol has an Apex extractor, USB, Hard Sear, Poly trigger, and 10-8 sights. At 580 rounds today, I switched the stock recoil spring out with a non-captured guide rod and an ISMI 17 pound recoil spring (and I immediately wished I'd bought the captured version of the guide rod).

On the last round in the mag, at round 596, the pistol had its first and only malfunction. The case mouth was caught on the top of the feed ramp as though it had a burr on it. I looked at it for a minute, ejected the round, couldn't find a burr, made that round the second round in my next mag, and kept on taking turns shooting the pistol with my buddies. I finished with a mag of Hornady Critical Defense, put the factory recoil spring assembly back in, and called it a night. The ammo we were shooting was 115 grain XTP traveling 1140ish FPS loaded to the Hornady manual specs, and I concluded the case mouth might not have been fully crimped back to spec.

My two shooting buddies are competent shooters, and each of us shoots a few thousand rounds a year, so I'd like to rule shooter error out of the equation, leading to my question. Has anyone ever bumped up the recoil spring to 17 pounds and found it to cause issues?

Edited June 14, 2014 by tcarp1911

[Sheperd80]

Sounds more like an ammo problem but im no gunsmith.

I went to a 17 lb. ISMI as well on my slightly older M&P 9 (dky prefix) using the stock guide rod and its been great for about 2 yrs/2000 rds.

Only malfunctions the gun has ever had were a few light strikes on Tula when i first got it. And i think that was caused by the globs of gunk i cleaned out of the striker channel afterwards. Never happened again.

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Edited June 14, 2014 by Sheperd80

[tcarp1911]

I'm actually quite convinced that it was the ammo, but I thought I'd ask. The case mouth felt sharp all the way around like it needed slightly more crimp. My notes showed the ammo being from spring of 2006 from a set of lee dies, so it certainly wasn't the best ammo I've ever made. Did the 17 pound spring make the return to battery seem a little sharper?

[Sheperd80]

I havent really noticed a difference in feel when it returns to battery. If its sharper it must be pretty slight, but i suppose that could potentially effect the cases as theyre forced into the chamber. If the recoil spring is outrunning the magazine spring maybe the round is going forward earlier and "lower" causing some collision. But again im no gunsmith, thats pure speculation. I save most of my brass and upon a quick once over inspection they look unaffected.

IIRC the springs from ISMI are slightly weaker than their listed strength, i.e. a 17# spring is closer to 16.5# for whatever thats worth.

Good luck, please keep us posted on your findings!

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Edited June 14, 2014 by Sheperd80

[Sheperd80]

One more note, although this isnt really related to your situation, it is spring related.

With various factory 115gr ammo i did notice a slight POI shift after changing springs. I was printing a little higher than i wanted with the stock spring, and the ISMI seemed to bring it down a little. Whether this was a result of lock-time, my follow-through, felt recoil impulse or some other factor i cant say but there was definitely a noticeable change for the better. FWIW

Edited June 14, 2014 by Sheperd80

[tcarp1911]

That's exactly the type of info I'm looking for. I'll note that anytime I test, I split my ammo between a couple of my other buddies to see if the results are repeatable and to ensure I'm not having an off day. For the purpose of disclosure, I have about 3500 rounds through 9mm M&Ps and my primary shooting buddies have at least twice that through Glocks.

[Sheperd80]

That's exactly the type of info I'm looking for. I'll note that anytime I test, I split my ammo between a couple of my other buddies to see if the results are repeatable and to ensure I'm not having an off day. For the purpose of disclosure, I have about 3500 rounds through 9mm M&Ps and my primary shooting buddies have at least twice that through Glocks.

For the record my experience with the M&P 9 is also limited compared to many competition shooters. Roughly 1500 rds, then changed springs and have fired another 2000 or so. And thats all factory ammo (fed, wwb, rem, fiocci, tula) as im not a handloader yet. Some of that is local uspsa, but most is at an indoor range.

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[ZackJones]

I may be mistaken but I thought the stock spring weight was 17 pounds so I wouldn't expect much of a difference. In my M&P's a run a 15 pound ISMI spring with tungsten guide rod. It's uncaptured and at first it was a pain to put it in but after you do it a few times it gets easier. I run minor loads in my M&P's. I tried a 13 pound spring be in back-to-back testing I shot the 15 pound better (got more A hits on USPSA target).

[tcarp1911]

My understanding is that the stock spring is 15-16 pounds. I may be wrong, but I want to say that I've seen this stated several different places. Either way, I think I'm going to continue experimenting back and forth between springs for the next 1000 rounds and see how it goes, reporting in every 250 rounds or so. This is really just an experiment to see if one thing works better than the other or if I simply end up liking one spring weight better.

Edited June 16, 2014 by tcarp1911

[tcarp1911]

Any issues with the tungsten guide rod? I thought I was reading that they break often.

[ZackJones]

Any issues with the tungsten guide rod? I thought I was reading that they break often.

I've only had it in the gun for a short while but so far no problems. Here's a link to a thread that you may find interesting: http://www.brianenos.com/forums/index.php?showtopic=194616

[Rolex]

I have the tungsten 4.5" guide rod and the ISMI 13 pound spring- 300 rounds so far- no problems with my reloads and factory.

[thermobollocks]

I have the tungsten 4.5" guide rod and the ISMI 13 pound spring- 300 rounds so far- no problems with my reloads and factory.

Is this in a 5" or 4" gun? In the 5", with the 13# spring and SSS tungsten rod, mine wouldn't go into battery reliably. The 15 runs great, but I haven't tried the 17.

[Rolex]

I have the tungsten 4.5" guide rod and the ISMI 13 pound spring- 300 rounds so far- no problems with my reloads and factory.

Is this in a 5" or 4" gun? In the 5", with the 13# spring and SSS tungsten rod, mine wouldn't go into battery reliably. The 15 runs great, but I haven't tried the 17.

It is the 5" Pro. with all apex parts inside. The 13 pound spring on the SSS 4.5" tungsten guide rod.

Are you running the stock parts inside? Or the Apex sear, trigger, ram and competition springs?

If not that could be the problem- the striker spring may be overpowering the trigger stock spring?

Edited June 16, 2014 by Rolex

[thermobollocks]

I have the tungsten 4.5" guide rod and the ISMI 13 pound spring- 300 rounds so far- no problems with my reloads and factory.

Is this in a 5" or 4" gun? In the 5", with the 13# spring and SSS tungsten rod, mine wouldn't go into battery reliably. The 15 runs great, but I haven't tried the 17.

It is the 5" Pro. with all apex parts inside. The 13 pound spring on the SSS 4.5" tungsten guide rod.

Are you running the stock parts inside? Or the Apex sear, trigger, ram and competition springs?

If not that could be the problem- the striker spring may be overpowering the trigger stock spring?

Apex sear, RAM, and competition springs. My trigger return spring is lighter than stock, but my striker spring is not.

Edit: I take that back. I wore out the competition trigger return spring and put the stock one back in.

Edited June 16, 2014 by thermobollocks

[Rolex]

I have the tungsten 4.5" guide rod and the ISMI 13 pound spring- 300 rounds so far- no problems with my reloads and factory.

Is this in a 5" or 4" gun? In the 5", with the 13# spring and SSS tungsten rod, mine wouldn't go into battery reliably. The 15 runs great, but I haven't tried the 17.

It is the 5" Pro. with all apex parts inside. The 13 pound spring on the SSS 4.5" tungsten guide rod.

Are you running the stock parts inside? Or the Apex sear, trigger, ram and competition springs?

If not that could be the problem- the striker spring may be overpowering the trigger stock spring?

Apex sear, RAM, and competition springs. My trigger return spring is lighter than stock, but my striker spring is not.

Edit: I take that back. I wore out the competition trigger return spring and put the stock one back in.

The stock trigger spring will work with the 13lb. recoil spring- BUT you most likely need to change out to the comp. striker spring so it wont fight the 13lb recoil spring.

[fdc1999]

I have the 9 Pro with the full Apex FSS kit. I run an 11lb ismi spring with the stock striker spring when I run my comp with factory 9, and the 13lb ismi without the comp. This is with a KKM barrel. I tried a Wolff 12lb spring, and I may have 1 or 2 light strikes in 100 rounds fired. Its solid with the 11 ismi.

[JMike]

This is good info folks! Thanks for taking the time to respond to the OP's questions. I know I have learned a thing or two from the knowledge base here!

Edited June 17, 2014 by JMike