Saturday, March 21, 2009

S+W M+P 9c magazine catch, modifications to suit

.I've owned and carried a S+W M+P 9c for a few years now. It's a wonderful carry pistol with some well thought out features. Controls are minimal, with no external safeties to deal with. The sights are decent, accuracy is exceptional, and the magazine capacity is sufficient. It's a joy to shoot, pointing naturally, with a decent trigger right from the factory.

All this is good..... but there is a fly in the ointment. The 9c has one flaw, and it's not insignificant.

After owning, shooting, and carrying the pistol for some months it began doing something disconcerting. The magazine would release and drop at times when I hadn't planned on doing so. Sometimes in the holster, and sometimes when I brushed the release while shooting the pistol. I discussed the issue back then, in a number of posts linked together.

At the time, I shipped the pistol back to Smith and Wesson for an updated magazine catch. Given the minuscule engagement of the catch to the magazine, it needed to be perfect. The one my pistol came with had taken some wear from normal use, and that contributing to the problem.

Smith and Wesson returned my pistol with a new catch installed. It appeared to be exactly the same, except it was coated with something slick to reduce wear. I've been using the pistol ever since with no problems, and have fired thousands of rounds through it. It's been a daily carry for CCW purposes, and the magazine catch issue has not reared it's ugly head..... till now.

I noticed a few times lately the magazine had released during normal handling. That's just not something I'm willing to tolerate in a defensive carry pistol. There's been no sign that Smith and Wesson has done anything new with the issue, so I've been left to my own resources. That is a sure recipe for disaster.

Here, in a series of photos and descriptions, I'll journal what I've done to my 9c to solve the problem. As in everything, your mileage may vary. I'm certain Smith and Wesson would frown on every single thing I've done here, and thats their prerogative. Of the other hand, this is my weapon and my responsibility, and I'm perfectly willing to rely on myself to fix a problem the manufacturer can't seem to.

Should someone else try to modify their own 9c as I have done? That's up to them, but I would encourage second thoughts first. Even the smallest mistake here might render the pistol useless or undependable. Most people would be better shipping their pistol back to S+W if they have this problem.

The magazine catch button on the 9c is pronounced, and protrudes past the body line of the pistol. While this makes it easy to operate for people with small hands, it also makes it possible to activate unintentionally by brushing the pistol with hand or holster.

The magazine has holes on either side to accommodate the ambidextrous latch mechanism. The problem is not in the magazine.... this arrangement is universally used in other firearms without problem.

Looking inside the magazine well to view the latch in operation, we find the latch itself and it's torsion bar spring which is permanently installed in the polymer molded frame. The latch can be easily removed and reversed for left handed shooters.

Tearing down a magazine and inserting the empty body into the well, we can see the magazine catch just barely engages the hole in the magazine body.
Measured with a vernier caliper, it amounts to about .020" of engagement, which is too close for comfort.

I chose to attack this problem in three ways at the same time. Each modification being small, but adding up to a magazine catch which works better than the factory allowed.

This is the magazine latch removed from the pistol. The limiting factor for it's ability to engage the magazine is how far it can protrude into the magazine well. This is determined by the lip in the plastic body just outboard of the metal catch itself. This lip seats on the frame, and limits the travel of the magazine catch into the well.

Using a razer knife and large lit magnifier, I trimmed back the lip about .020" all the way around the magazine catch, as shown. Dressed with a fine square file after being trimmed, it allowed the catch to seat that much deeper into the frame.

Taking care of the catch so it could engage deeper, I turned to the torsion bar spring. It seemed weak, again making the catch easier to operate for people with small hands. I have large hands and can deal with more tension on the latch, so wished to have a firmer spring.

The torsion bar spring is not replaceable, so I chose to strengthen what was there. Cutting the plastic body from a Q-tip to length, I carefully installed the plastic tube onto the torsion bar. There, it shimmed the bar tighter, and acted as a spring itself when it came up against the frame on activation.
The tiniest drop of 241 Loctite on the bar keeps it in place.

Here, the latch mechanism is fully assembled and the empty magazine body once again installed, we can see the latch engagement is considerably deeper. In fact, it's just about doubled. In addition, it requires a firmer activation of the latch to drop the magazine.

The last step was to carefully reduce the outside dimension of the latch button so it would be less likely to inadvertently drop the magazine.

With a fine file and emery cloth I removed some material from the button surface.

up the three modifications, I have a great deal more confidence in the magazine catch on my S+W 9c. It feels firmer and less likely to drop the magazine by mistake.
Any pistol shooter can drop a magazine from their weapon, and training is the best cure for that. Starting with a pistol that doesn't do so by itself... that is a good first step.


Several weeks of carry and several hundred rounds later, the modifications seem to be working perfectly. The plastic tube has not slipped at all, and the magazine is firmly retained yet easy to remove.


Conservative Scalawag said...

Nice bit of guerilla gunsmithing there. Thanks for sharing it.

Old NFO said...

Nice work Sir! And yeah, probably not authorized, but what the hey... If it works, it works!

Anonymous said...

Q-tips to the rescue again??

Ron said...

Hello - I enjoy your blog. This post on the SW MP 9 is very timely - I just bought one and like it a lot. I have not shot it much and not encountered the release catch problem yet. Thanks for the well presented approach to the problem. Do you shoot this gun a lot ? Is it likely SW will modify the catch in your opinion ? Thank you for a fine blog. Best Wishes: Ron

Carteach0 said...

I believe S+W has already solved the issue on the newer M+P compacts. The older ones, I don't know if they have a fix for them. If they do, they have not chosen to share it with me, and they know who I am and how to reach me.

I shoot my 9c quite a bit, carry it often, and enjoy it.

fast richard said...

I like the way you chose to trim the latch piece to increase latch engagement.

I have a question about the Q-tip on the spring bar. Is there anything securing it in place? Or, would there be a way for it to work loose and cause a problem? Even if it is a tight press fit, you might want to keep an eye on it, to see how it holds up.

Carteach0 said...

Richard: Good question, and points out something I forgot to mention. Now corrected.

Yes, a tiny drop of 241 Loctite keeps the tube in place, along with the spring pressure. With several hundred rounds fired it has not moved at all so far.

tooldieguy said...

A friend of mine had the same problem and I drilled a small hole in a piece of 1/8 brazing rod to slip over the spring.

JR said...

Has this modification made it significantly harder to insert the magazine?

Carteach0 said...


I've noticed no change at all with inserting a magazine.

Like I stated in the post, I would not suggest this type of modification for someone who's not comfortable with working on their own firearms.
Most people should just take it a reputable gunsmith, or ship it to the maker. This was just *my* solution to the problem.

Ed Foster said...

Former S & W engineer here, and my son is a police detective who carries an M & P 45 for a living.

The problem is fairly typical of any synthetic recievered weapon, because of the draft angle needed to withdraw the reciever from the mold. A bigger latch reduces pendulum effect, but also increases wear on the latch.

Another problem with concealed carry of M & P's is safety "wipe-off". Blue suits don't have the problem because of their big, roomy duty holsters, but from a pancake it's downright scary.

There's talk up at Smith about going to a heavier detent, but just as many against it as for it, fearing many women and some smaller men might not be able to function the weapon properly in a stress situation.

Carteach0 said...


Thanks for the input!

I am not familiar with the term 'Safety Wipe Off', but my mind is conjuring some pretty nasty ideas.
Please share?

As for the magazine latch issue, I has also considered a simple molded rubber bushing to fit in the well behind the torsion bar, supporting it and adding to it's tension. Nothing more complicated than an oblong piece of stiff rubber with a slot in it for the bar to ride in, slid in behind the torsion bar. This could be an add on for those have no problem pushing the button firmly.

I will say my M+P 9c has the lightest and easiest to release magazine catch I have ever run into. Frankly, a bit too light.

It's a problem, but not enough of one to make me disfavor the M+P, or not consider owning another. I'd like to have a full sized .45 version. If they shoot as well as this 9c, I'd be more than happy.

Ed Foster said...

The detent cam slot is rather minimal, and in a draw from the Hartford PD mandated hard pancake for detectives, the safety usually gets bounced to the fire condition.

Qual scores are down somewhat in the HPD since the switch from the S&W 4506, which is understandable when you consider the loss of 7 ounces of steel, especially at the bottom where it has the mass and leverage to act as a damper.

Most of the uniformed officers would rather have stayed with the 4506. Given the "Batman Utility Belt" issued with the blue suit, the weight isn't a big deal. But the detectives seem to like the lighter M&P better for concealed carry.

Other than a renewed emphasis on muzzle control, the wipe-off isn't that much of a problem, but people are worried lest some lawyer hear about it and sue for endangering badguys or something.

Son One had a really nasty shootout recently(third medal of valor), and the M&P performed quite well indeed.

When I was at Colt's back in the 90's, we had a jolly old time getting the molds ready for the Colt .22 Auto (now the Beretta). But the reciever was partially synthetic and partially steel. We were able to get the draft angle from the top, with a snug bottom, and the mag lips nestled into a steel feedramp, so the magazine was trapped solidly at both top and bottom. Quite slick, and no, the dopey mag release wasn't my idea guys, honest.

And by the way, I really do enjoy your blog. Keep up the good work.

Robert Chambers said...

This is a problem with the M&P45 full size also.

If you are practicing with short loaded magazines as I was taking some training and load 3-4 rounds in the magazine, the mag follower fouls the hole where the mag catch sits. I'm a lefty so my mag release is on the left-hand-thumb side of the pistol which makes the situation worse.

Put a 3 or 4 round loaded mag into the pistol, rack the slide and take the shot, the magazine forcibly ejects. More rounds than that and it's fine. S&W wanted me to send my pistol to them but I told them just get a standard 45 magazine and put 3 or 4 rounds in it and you'll see what I see. "Can't do that we aren't allowed to have ammunition" Ok, put 3 or 4 dummy rounds or snapcaps in there "Can't do that either" "So what kind of firearms manufacturer can't test their pistols?"

I'm not happy with their lack of a response but I'm going to have to look into your method.

Robert said...

Update: speedshooter specialties has these items (the mag release catch) for sale $4 each so I got a couple and performed the delicate surgery you mentioned on one of them. The metal catch does come further forward now. Haven't tried it at the range yet but figured I'd throw out the option for those that perhaps don't want to modify their original equipment.