ZackJones Posted March 25, 2014 Share Posted March 25, 2014 I did a search and found a thread from 2009 so I'm thinking things may have changed a little since then . From what I understand you can put a 9mm barrel and use 9mm mags in an M&P 40 and it will work. Is that correct? Has anyone here actually tried it? I prefer to shoot .40 but my wife seems to like 9mm so before I go buy a 9mm for her I thought I'd try the barrel and magazine thing first to see if she really does prefer 9mm to .40. FWIW I will be working up the loads for each. Thanks in advance for your feedback. Link to comment Share on other sites More sharing options...
scottlep Posted March 25, 2014 Share Posted March 25, 2014 I know a few people that have Storm Lake and other brand barrels to convert their M&P Pro .40 to 9mm. Storm Lake makes a specific barrel for the conversion if you look at their website. I don't think you can just go grab any 9mm M&P barrel and drop it right into the .40 though. Link to comment Share on other sites More sharing options...
razorfish Posted March 25, 2014 Share Posted March 25, 2014 (edited) Interestingly enough, last weekend my fourteen year old son and I drove over an hour to the USPSA range to get in some practice. As we unloaded the truck my son announced, "I forgot my pistol". Whaaat... Ok he shoots an M&P 9mm full size. 4.25" barrel I believe. In his range bag is a backup gun (M&P 40SW). I keep this pistol in his bag as the lower is interchangeable as well as the recoil spring and the striker. I also had the old barrel to his 9mm in the bag (I upgraded to the new barrel in his current pistol). Luckily he only forgot his pistol and all of his mags were in the range bag. So, we swapped the 9mm barrel in the 40 upper and he shot all day (approximately 400 rounds). He was having an issue with the slide locking back after an empty mag, but other than that, everything went fine. I can't say this would be a long term solution, but in a pinch, it worked fine for us. Again, these are M&P full size pistols and not PRO long slides. YMMV. Edited March 25, 2014 by razorfish Link to comment Share on other sites More sharing options...
horseman Posted March 25, 2014 Share Posted March 25, 2014 I have about 7000 rounds of 9mm through my 5 inch pro 40. I bought a take off factory barrel from a great guy here, 9mm mags and it has ran flawlessly. With the exception that it will not lock back on last round. As I use it with TF mag extensions holding 23 9mm rounds it is not much of an issue in 3 gun. Be advised I don't know if this is safe or prudent just reporting my experience. Link to comment Share on other sites More sharing options...
ZackJones Posted March 25, 2014 Author Share Posted March 25, 2014 Appreciate the feedback. If I happen across a 9mm barrel I may pick it up and give it a try. On the other hand I may just have to buy her a 9mm. Afterall if she's shooting my gun with a 9mm barrel in it what am I supposed to shoot?? Link to comment Share on other sites More sharing options...
awfaxis Posted March 26, 2014 Share Posted March 26, 2014 Interesting. I bought the KKM conversion barrel, and don't have any issues with slide lock, or anything. Not sure why having a 9 barrel would do that. The only physical issue with a 9 barrel in a 40 slide is the extra slop at the breach/chamber interface. Link to comment Share on other sites More sharing options...
razorfish Posted March 26, 2014 Share Posted March 26, 2014 I'm thinking there is a difference in the slides... Although my 9mm barrel fits my 40 slide, the opposite is not true. The 40 barrel doesn't fit the 9mm slide. Link to comment Share on other sites More sharing options...
p5200 Posted March 26, 2014 Share Posted March 26, 2014 Interesting. I bought the KKM conversion barrel, and don't have any issues with slide lock, or anything. Not sure why having a 9 barrel would do that. The only physical issue with a 9 barrel in a 40 slide is the extra slop at the breach/chamber interface. I also, put a KKM conversion barrel in my m&p 40 and have been reloading for it and really like it's performance I also, installed one of the fail safe extractors and competition trigger kits. I think, the extractor brand and trigger kit is Apex Tactical brand if I remember right. Link to comment Share on other sites More sharing options...
hops Posted March 26, 2014 Share Posted March 26, 2014 Interestingly enough, last weekend my fourteen year old son and I drove over an hour to the USPSA range to get in some practice. As we unloaded the truck my son announced, "I forgot my pistol". Whaaat... Ok he shoots an M&P 9mm full size. 4.25" barrel I believe. In his range bag is a backup gun (M&P 40SW). I keep this pistol in his bag as the lower is interchangeable as well as the recoil spring and the striker. I also had the old barrel to his 9mm in the bag (I upgraded to the new barrel in his current pistol). Luckily he only forgot his pistol and all of his mags were in the range bag. So, we swapped the 9mm barrel in the 40 upper and he shot all day (approximately 400 rounds). He was having an issue with the slide locking back after an empty mag, but other than that, everything went fine. I can't say this would be a long term solution, but in a pinch, it worked fine for us. Again, these are M&P full size pistols and not PRO long slides. YMMV. He shoots the m&p 9mm in Production? I do not think that is allowed. I was looking through the rules and believe i read that a barrel can be changed but it has to be the same caliber, you cannot change calibers. Would hate to see him get DQ'd. Link to comment Share on other sites More sharing options...
ZackJones Posted March 27, 2014 Author Share Posted March 27, 2014 He shoots the m&p 9mm in Production? I do not think that is allowed. I was looking through the rules and believe i read that a barrel can be changed but it has to be the same caliber, you cannot change calibers. Would hate to see him get DQ'd. I was thinking about that very thing this morning on the way to work. I'm trying to get my wife interested in shooting steel challenge. I'm the MD at our local club and she helps with registration. I'm thinking a 9mm would be better for her but changing calibers with a conversion barrel and staying in production division isn't allowed. I guess I just need to buy her a 9mm C.O.R.E. model put a red dot on it and have her shoot open. I'd bet she'd like that. Link to comment Share on other sites More sharing options...
CrawfishStu Posted April 3, 2014 Share Posted April 3, 2014 I run a storm lake 40 to 9 barrel in my Core Pro Long. I did check out the fit of my 9L barrel into the 40L slide. Did not shoot it. I remember several tolerances that I mic'd out being different. What would cause the lack of lock up at an empty mag? Link to comment Share on other sites More sharing options...
JPB Posted April 8, 2014 Share Posted April 8, 2014 I use the Storm Lake 40 to 9 barrel as well in my Core. Works great, no issues. Link to comment Share on other sites More sharing options...
msg73 Posted April 10, 2014 Share Posted April 10, 2014 I have an M&P 40 and have used the factory 9mm barrel in it...ran fine. The barrel hood is a tad smaller on the 9mm, so it fits the 40 (with a little slop). However, the 40 barrel hood is a tad too wide to fit a 9mm slide. Almost all other dimensions of the two barrels were the same. The 40-to-9mm conversion barrels have the 9mm bore with the width of the 40 hood. If you reload, why not just load 40 minor Instead of getting a new 9mm barrel and mags? Sure, reloading 40 may cost a little more but it'll take a good amount of shooting to go though the savings of not having to buy the 9mm barrel and mags. Link to comment Share on other sites More sharing options...
okorpheus Posted April 10, 2014 Share Posted April 10, 2014 Interestingly enough, last weekend my fourteen year old son and I drove over an hour to the USPSA range to get in some practice. As we unloaded the truck my son announced, "I forgot my pistol". Whaaat... Ok he shoots an M&P 9mm full size. 4.25" barrel I believe. In his range bag is a backup gun (M&P 40SW). I keep this pistol in his bag as the lower is interchangeable as well as the recoil spring and the striker. I also had the old barrel to his 9mm in the bag (I upgraded to the new barrel in his current pistol). Luckily he only forgot his pistol and all of his mags were in the range bag. So, we swapped the 9mm barrel in the 40 upper and he shot all day (approximately 400 rounds). He was having an issue with the slide locking back after an empty mag, but other than that, everything went fine. I can't say this would be a long term solution, but in a pinch, it worked fine for us. Again, these are M&P full size pistols and not PRO long slides. YMMV. He shoots the m&p 9mm in Production? I do not think that is allowed. I was looking through the rules and believe i read that a barrel can be changed but it has to be the same caliber, you cannot change calibers. Would hate to see him get DQ'd.Woildnt be a DQ, just a trip to open. Minor. Without a dot. Or a comp. Link to comment Share on other sites More sharing options...
fdc1999 Posted April 16, 2014 Share Posted April 16, 2014 So, thinking out of the box, can you take a M&P in 9mm, put on a 40 slide, drop in the 40 to 9 conversion barrel, and still be in production? You did change the barrel for the caliber it originally came in! Link to comment Share on other sites More sharing options...
FJR05 Posted April 20, 2014 Share Posted April 20, 2014 The slide is marked 40 or 9. So putting on a 40sw slide on a 9mm frame, then putting the 40 to 9 conversion barrel in it would not be Production legal. Technically, swapping a complete 9mm top end onto a 40 M&P frame would not be legal either. But unless the chrono guy(inspector) has a list of serial numbers per caliber only you would know any different. Link to comment Share on other sites More sharing options...
darkhelmet47 Posted April 28, 2014 Share Posted April 28, 2014 If you reload, why not just load 40 minor Instead of getting a new 9mm barrel and mags? Sure, reloading 40 may cost a little more but it'll take a good amount of shooting to go though the savings of not having to buy the 9mm barrel and mags. 40 minor shoots really nice, I have load data for several powders in 40 minor if you are interested. Link to comment Share on other sites More sharing options...
tires2burn Posted June 6, 2014 Share Posted June 6, 2014 I just got a full size MP40 and before I shot it I purchased a Storm Lake 9mm conversion barrel and 2 9mm S&W mags. I ran 300 rounds of the 40 and switched barrels and ran 300 9mm. Not one single hiccup with either barrel. I am more than pleased with storm lake. All I had to swap was the barrel and mags. Link to comment Share on other sites More sharing options...
ZackJones Posted June 6, 2014 Author Share Posted June 6, 2014 I use the KKM 40-to-9 conversion barrel in my CORE and shoot that in steel challenge and it works very well. Today I'm picking up a 9mm pro for Mrs. Jones . Link to comment Share on other sites More sharing options...
mwx40x40 Posted August 9, 2014 Share Posted August 9, 2014 (edited) I just purchased a Storm Lake conversion for my M&P 4.25 40. Went to the range Thursday and ran about 200 rounds of all sorts of 9mm loads and it was flawless. However, during my testing I a shot to slide lock every time. Today I ran a club level USPSA match with the conversion barrel and it ran fine again, but every time at Unload and show clear , I could not get the live round out. Round seemed locked in pretty good and when finally retracted the slide the extractor would jump over the rim. Ended up having to fire gun every time to clear. So my question is ..... Do you think this is chamber related or extractor? Extractor will hold 40 pretty firm , 9mm is pretty lose. BTW, not one single malfunction or failure to extract while shooting. Edited August 9, 2014 by mwx40x40 Link to comment Share on other sites More sharing options...
Steve RA Posted August 9, 2014 Share Posted August 9, 2014 Try a "plunk" test in the barrel, round could be a little too long or a hair too much diameter with a bullet in the case. Link to comment Share on other sites More sharing options...
wgj3 Posted August 9, 2014 Share Posted August 9, 2014 Was the ammo reloads? Link to comment Share on other sites More sharing options...
mwx40x40 Posted August 10, 2014 Share Posted August 10, 2014 Was the ammo reloads? Yes reloads, but they pass the chamber check tool gage, but, when I tried plunk test they were not 100%. Guess chamber is hair tight. Same ammo extracts to show clear from my G34, M&P 9, XDM 9 and G26 just fine. I had a Wolf conversion for my G22 that had to be reamed , but it was so tight the slide would not lock up in battery. The strange part to me about the SL BBL is how it runs 100% on several of my reloads. No failures to feed or extract. Only at unload and show clear does it not extract. Link to comment Share on other sites More sharing options...
Woodsk Posted August 12, 2014 Share Posted August 12, 2014 The chamber on the storm lake conversion barrels is much tighter than that of that of the stock M&P barrel. You can test this your self by taking the barrels out and using the same round to chamber check in each on. You will find that the stock barrel has room for the round to move around in the chamber while the storm lake chamber is nice and snug. If you are going to reload for the storm lake barrel an undersized die is a must other wise you will have issues with rounds getting stuck. btw- the chamber on my storm lake barrel is tighter than my dillion case gauge. Link to comment Share on other sites More sharing options...
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