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  #1  
Old 12-15-2011, 01:51 AM
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Default M&P extraction problem

I just discovered a potential problem with both of my 9mm S&W M&P pistols - an M&P 9 fullsize and an M&P 9c compact pistol.

I normally leave a snap-cap in the chamber of those two pistols, since they have the old-style firing pins which are subject to breakage if dry-fired without a snap-cap in place. (Happened to me once on the M&P 9).

Well, this evening I was starting to practice some loading and clearance drills with the fullsize. Normally, I use dummy ammo for this -- cases that have been sized, but not decapped, and a bullet seated to correct OAL and no powder in the case. However, this evening, I was lazy and grabbed some snap-caps, which were at the moment handier than the dummy ammo. The snap caps are the type with a clear red plastic body (.40s are blue) and a brass base. There is a movable piece where the primer goes, and you can see through the red case and see the spring inside the snap-cap that the "primer" area pushes against when the firing pin hits it.

Lo and behold, my M&P wouldn't extract/eject the snap-caps when I racked the slide, regardless of whether I racked it medium speed or very quickly. The slide locked back (mag was empty) and the snap-cap was left lying with its rear end on top of the magazine and its nose still in the chamber. I tried it with several snap-caps, some used and some brand new. I tried different racking speeds. All with the same result - no extraction/ejection of the snap-cap.
My first thought was that I possible had a broken/worn part in the pistol. So I got out my M&P 9c compact and tried it. Same exact thing.

So I then tried my carry ammo, which is 9mm PowerBall. It performed perfectly, extracting/ejecting properly in both the M&P 9 and the M&P 9c. Distance it flew was proportion to slide racking speed. I then tried a bunch of different live ammo, including: PMC (Korean) FMJ, Win FMJ, Win JHP, and my reloads using various brand cases. All of the live ammo functioned properly, as did my dummy ammo, in both guns.
So, while the "real" ammo seems to function properly, the snap-caps don't extract/eject in either of my M&P pistols.

I then tried the snap-caps in two of my 9mm Glock pistols - a G19 and a G26. The snap-caps extracted/ejected fine in both of them.

I examined the bases of the snap-caps. I didn't use a mircometer, but the diameter of the base of the snap-caps appeaars to be the same as the diameter of the base of my carry ammo. The only difference is that the rim thickness of the snap-caps appears to be thinner than the rim thickness of any of my "real" ammo.

Any ideal? Thanks,

Bob
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Old 12-15-2011, 05:35 AM
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Well, since they work fine with real ammo, it's not a really big deal. Frustrating, but not necessarily a real problem. However, I'd make an effort to do a real thorough cleaning job on the extractor area on both pistols in case accumulated crud may be contributing.

I'd also suggest actually measuring the dimensions of the 'case head' area of the snap caps and compare them to actual case dimensions. I'd also suggest making sure the snap caps can fall out of the chamber by their own weight if the barrel is turned muzzle up. That it only happens with the snap caps suggests they may be the issue even if they do work in the brand "G".

Last edited by WR Moore; 12-15-2011 at 05:37 AM.
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Old 12-15-2011, 05:38 AM
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Well, since they work fine with real ammo, it's not a really big deal. Frustrating, but not necessarily a real problem. However, I'd make an effort to do a real thorough cleaning job on the extractor area on both pistols in case accumulated crud may be contributing.

I'd also suggest actually measuring the dimensions of the 'case head' area of the snap caps and compare them to actual case dimensions. They do wear you know.
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Old 12-15-2011, 10:14 AM
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No problem - snap caps are finicky as far as which weapon they want to work in. I have a different brand (not in front of me right now). Worked fine in a High-Point C-9, ejected poorly in a High-Point 995ts and work fine in a M&P 9c, Find somebody that can load some dummy rounds for you.
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Old 12-15-2011, 12:13 PM
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Talaub -- As I mentioned in my original post, I do use dummy rounds that I make.

I think I'll have to break out my calipers and micrometer and see if I find any noticeable differences.
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Old 12-15-2011, 07:40 PM
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Snap Caps is a brand name. You using these? Plastic dummy cartridges with a spring inside? They're not made to load/eject from auto pistols and will eventually wear out. Recall the typical cartridge case does this one (1) time before it's discarded.

-- Chuck
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Old 12-15-2011, 07:48 PM
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I'd chalk this one up to wear on the plastic Snap Cap rims. Snap Caps are expendable items and wear out just like brass cases, though at a faster rate. Plastic < brass.
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Old 12-15-2011, 08:44 PM
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Quote:
Originally Posted by Dragon88 View Post
I'd chalk this one up to wear on the plastic Snap Cap rims. Snap Caps are expendable items and wear out just like brass cases, though at a faster rate. Plastic < brass.
In my original post above, I wrote: "I tried it with several snap-caps, some used and some brand new. "

So I don't think it's an issue of the snap caps being worn.
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Old 12-15-2011, 11:35 PM
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Quote:
Originally Posted by chuck s View Post
Snap Caps is a brand name. You using these? Plastic dummy cartridges with a spring inside? They're not made to load/eject from auto pistols and will eventually wear out. Recall the typical cartridge case does this one (1) time before it's discarded.

-- Chuck
Chuck,
The snap-caps I used were not the Snap Cap brand - that's why I did not capitalize the name in my original post. The brand I used is "Traditions" - probably a bigger seller than the Snap Cap brand.

As I stated in my original post, I also tried some brand new snap-caps, and achieved the same non-functioning results.

As far as the typical cartridge case being used once and then discarded... I'm afraid a few hundred thousand reloaders might disagree with you. I don't think normal wear of a regular ammo case would cause this problem - I (as well as a majority of handloaders) have handgun ammo cases that have been reloaded many times and still function properly. Ask any IPSC or IDPA shooter who reloads his own ammo (which most of them do).

Now, on the other hand, the base of the snap caps might be made of a different material (i.e., softer brass) that could possibly cause them to wear faster than regular ammo. However, that still doesn't explain the fact that my problem was also noted with brand new snap caps.

No, I think the problem lies in some dimensional difference between the snap caps and regular cartridge cases. As soon as I find my micrometer (hidden since my last engine rebuild), I''ll attempt to do a physical dimension comparison between the two.

In the meantime, I'll contact S&W and see what they have to say about the issue. I've always found their customer service personnel to be helpful.
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Old 12-15-2011, 11:43 PM
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I think they'll ask you if the pistols cycle real ammunition fine. When you say "yes", I suspect they'll tell you that there is nothing wrong with your guns. Your pistols are designed to cycle brass-cased ammunition, not snap caps. While exploring the reason why the snap caps do not extract may be an interesting endeavor, it does not indicate that your pistols have "extraction problems" IMO. Don't blame the guns until they fail to extract real brass cases.
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Old 12-15-2011, 11:47 PM
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Quote:
Originally Posted by Dragon88 View Post
I think they'll ask you if the pistols cycle real ammunition fine. When you say "yes", I suspect they'll tell you that there is nothing wrong with your guns. Your pistols are designed to cycle brass-cased ammunition, not snap caps. While exploring the reason why the snap caps do not extract may be an interesting endeavor, it does not indicate that your pistols have "extraction problems" IMO. Don't blame the guns until they fail to extract real brass cases.
I'm not blaming the guns. If I were, I'd have already sent them back to S&W. I'm merely reporting an anomaly, noting that that anomaly doesn't exist with my Glock 9mm pistols (or H&K, or Kel-Tec, or Ruger).
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Old 12-16-2011, 05:41 PM
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Well, guys, I think I've found the major cause of the problem with the snap-cap ammo. BTW, I am not using the "Snap Cap" brand, but rather the brand "Traditions" which is likely a bigger seller (at least in Michigan) than the original brand.

Anyway, I finally found my micrometer and calipers, and I took various measurements of the snap cap and loaded ammo -- in this case, PowerBall 9mm ammo. I only found two dimensions that were really different, but those two dimensions likely relate directly to my extraction problem. They were: (1) Rim thickness; and (2) Rim diameter.

The PowerBall ammo was exactly what SAAMI (Sporting Arms and Ammunition Manufacturer's Institute) specifications state they should be. Rim Thickness was 0.035" and Rim Diameter was 0.392".
The snap cap ammo had significantly different dimensions. Rim Thickness was smaller than SAAMI, at 0.025". Rim Diameter was also smaller than SAAMI, at 0.377". So the snap cap rims were 0.010" smaller in thickness, and 0.015" smaller in diameter, than SAAMI specs.

I don't have the capability to measure the difference between the S&W M&P pistols and the Glock pistols, in order to explain why the snap caps work in the Glocks, but not in the M&P's. However, I suspect that one or both of the following differences exist: (1) The tip of the Glock's extractor claw extends further into the extraction groove than does the claw of the M&P; and (2) The spring tension on the extractor claw is greater on the Glock than on the S&W.

So, I'm satisfied that there's nothing wrong with my 9mm M&P pistols, and I've put them back into service. Thanks to all forum members who obsessed with me on this issue.

Bob
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Old 12-16-2011, 09:57 PM
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Upon reflection, I don't believe spring tension would have any effect on extraction of undersize rims. It's strictly a question of an ability to engage the rim. That being said, if the Glockish extractors have more range of travel, allowing them to engage an out of spec rim is a possibility.

While S&W doesn't require the use of guages to fit M&P extractors anymore, every M&P9 extractor I ever gauged (with factory gauges) had what the gauges evaluated as an excessive range of travel. So, those snap cap rims have waaay undersized heads.
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