View Full Version : Storm Lake M&P .40 to 9mm COnversion Barrel Information
GLOCKMASTER
12-29-10, 16:55
I searched and found a lot of outdated information so I started a new thread to ask the below question.
I'm considering buying a Storm Lake 9mm conversion barrel for my M&P .357 SIG. Has anyone been using the Storm Lake conversion barrel in an M&P and if so what has been your experience with it?
Thanks!!
I have both a Storm Lake 9mm and a factory 40s&w barrel for my M&P357. Both drop right in and I have never experienced any type of failure. I use the stock spring and shoot my own reloads and a mix of factory JHP/FMJs but NO Wolf or related steel cased ammo. The 9mm barrel shoots a fine as my factory M&P9c and at 25yrds both the 9mm and 40s&w will group in the 2.5 to 3.0 range if I do my job. I wouldn't hesitate to recommend the Storm Lake kit.
GLOCKMASTER
12-29-10, 20:34
Thanks Irish I appreciate your input.
Singlestack Wonder
12-29-10, 20:44
Keep in mind that the breechface cut on the slide is dimensioned for 357SIG (same cartridge base dimension as 40S&W) and will have a lot of space around the 9mm cartridge base allowing it to float around the breechface area. The other issue is that the extractor is designed to work with the 357SIG breechface and cartridge base dimensions and will not always fully engage the 9mm case.
While it may work OK at the range, I would not depend on it for self defense.
GLOCKMASTER
12-29-10, 21:08
Keep in mind that the breechface cut on the slide is dimensioned for 357SIG (same cartridge base dimension as 40S&W) and will have a lot of space around the 9mm cartridge base allowing it to float around the breechface area. The other issue is that the extractor is designed to work with the 357SIG breechface and cartridge base dimensions and will not always fully engage the 9mm case.
While it may work OK at the range, I would not depend on it for self defense.
Thanks for your input. I have an associate that has over 2000 rounds with one with only two malfunctions.
It's going to be a range only conversion as I know better than to depend on it for self defense.;)
Just ordered the barrel and I will report back later on it's performance.
I shoot one for the .40 (40 -> 9mm). It functions fine though it will occasionally throw brass in your face.
Does anyone run a different recoil spring when using the conversion? I have heard that if doing the swap in a Glock you should also run a 9mm spring, anyone know about the M&P? I haven't had any issues with mine but I'm curious.
Does anyone run a different recoil spring when using the conversion? I have heard that if doing the swap in a Glock you should also run a 9mm spring, anyone know about the M&P? I haven't had any issues with mine but I'm curious.
Running straight conversion and mags with mine. Haven't switched out recoil springs. Two FTEs in roughly 2-3k, with one in the first 20rds. Other than that, it's run extremely smoothly.
I just got my conversion barrel for M&P FS 40-9mm. 2 malfunctions (FTE) in first 200 rounds. Seemed like one FTE after every 100. I used Blazer Brass 124gr and Atlanta Arms and Ammo 147gr. It felt like the slide/spring setup was too heavy for the loads used. Not quite as bad as using a .22 conversion on a Glock (with non-recommended ammo) but felt like I need to break in/shoot more to smooth out the barrel some. Will report again after the next few hundred rounds.
The springs are inexpensive enough to have the proper replacement and one to experiment with.
http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=27974
The 9&40 springs are the same part, but the 357 sig is different.
How does the factory design compensate for the increased recoil impulse?
Are the 40 slides heavier or is the locking geometry different?
Does anyone run a different recoil spring when using the conversion? I have heard that if doing the swap in a Glock you should also run a 9mm spring, anyone know about the M&P? I haven't had any issues with mine but I'm curious.
My M&P 40 came with the Green RSA. I called S&W and was told that the replacement for it and the 9mm was the Blue. With the Green 9mm ammo seems to dribble out. Feels like a Glock with 22 conversion. Will be trying the Blue RSA to see if anything changes.
Based on some research on the S&W forum it would appear the Green RSA is 17lbs while the blue is 16lbs.
BTW it seems that the 9mm slide has some metal cut out that the 40 S&W doesn't. Presumably this is to deal with the lower recoil impulse of the 9mm considering the gun was engineered for 40 S&W first.
Back from range. 300 rounds using Blue RSA. 100 Atlantic Arms 147gr, 100 Blazer Brass 124gr, 100 American Eagle 147gr. Erratic ejection much reduced with zero malfunctions. The Blue RSA is indeed the way to go over the Green.
Also, Grant had once mentioned his negative experience with Blazer Brass. Though at the time i had not noticed the same i believe i see what he sees. The conversion tends to react to this brand in a much more negative way than the others. More brass to face and erratic ejection. The Atlanta Arms and Ammo which works great in Glock 17's, feels like a .22lr in this setup. The American Eagle 147gr was the most consistent.
My M&P 40 came with the Green RSA. I called S&W and was told that the replacement for it and the 9mm was the Blue. With the Green 9mm ammo seems to dribble out. Feels like a Glock with 22 conversion. Will be trying the Blue RSA to see if anything changes.
Based on some research on the S&W forum it would appear the Green RSA is 17lbs while the blue is 16lbs.
BTW it seems that the 9mm slide has some metal cut out that the 40 S&W doesn't. Presumably this is to deal with the lower recoil impulse of the 9mm considering the gun was engineered for 40 S&W first.
My M&P 40 came with the blue RSA. Does the pound difference make much of a change?
PatrioticDisorder
06-22-14, 19:13
My M&P 40 came with the blue RSA. Does the pound difference make much of a change?
My M&P 40 with storm lakes conversion barrel and green spring have run reliably. There is about a 3lbs difference and I'm sure to blue spring would provide me with even more margin for not having a malfunction with weak ammo.
My M&P 40 with storm lakes conversion barrel and green spring have run reliably. There is about a 3lbs difference and I'm sure to blue spring would provide me with even more margin for not having a malfunction with weak ammo.
I've been considering doing a 40-9 barrel swap so I will give it a shot and try it with the current RSA and see how it works.
I would really like a 40c to 9mm threaded conversion barrel, but they're apparently harder to come by than most.
Howdy,
Keep in mind that the breechface cut on the slide is dimensioned for 357SIG (same cartridge base dimension as 40S&W) and will have a lot of space around the 9mm cartridge base allowing it to float around the breechface area. The other issue is that the extractor is designed to work with the 357SIG breechface and cartridge base dimensions and will not always fully engage the 9mm case.
While it may work OK at the range, I would not depend on it for self defense.
A 9mm brass has a head size of .394" and a .357Sig/.40S&W is .423" for a total difference of .019". This equates to .0095" of slack on all sides of the 9mm brass over the .40S&W brass.
.0095" isn't much.
I have a Lond Wolf 40-9mm conversion barrel for my G23 and after +15,000 rounds it's flawless except for one of my crappy reloads.
Paul
Howdy,
A 9mm brass has a head size of .394" and a .357Sig/.40S&W is .423" for a total difference of .019". This equates to .0095" of slack on all sides of the 9mm brass over the .40S&W brass.
.0095" isn't much.
I have a Lond Wolf 40-9mm conversion barrel for my G23 and after +15,000 rounds it's flawless except for one of my crappy reloads.
Paul
Might not be much, but I believe it accounts for the majority of the fte. There is a reason S&W didn't just reconfigure the barrel when engineering the 9mm version of the M&P. I agree that it's fine/fun for the range but I wouldn't load it up with HST's and put it in the Gunvault at night.
PatrioticDisorder
06-24-14, 06:40
Might not be much, but I believe it accounts for the majority of the fte. There is a reason S&W didn't just reconfigure the barrel when engineering the 9mm version of the M&P. I agree that it's fine/fun for the range but I wouldn't load it up with HST's and put it in the Gunvault at night.
Green spring 17lbs, blue spring 15lbs, likely the cause of your malfunctions with weak/cheap range ammo. Mine has run fine with the green spring and stork lakes conversion barrel but I tend to stay away from blazer. Keep in mind M&P 9mm & .40 share the same extractor, ejector and both can run reliably with the blue recoil spring. Also if you have an early model M&P 9mm you may want to consider an Apex FRE, had a friend who was getting some brass to the face with the conversion barrel (but otherwise running fine) and it was cured with the Apex FRE.
If you read through the forums, virtually everyone running the conversion barrel in their M&P has done so issue free. Those that have had issues tended to stem from green recoil spring and crappy range ammo.
Green spring 17lbs, blue spring 15lbs, likely the cause of your malfunctions with weak/cheap range ammo. Mine has run fine with the green spring and stork lakes conversion barrel but I tend to stay away from blazer. Keep in mind M&P 9mm & .40 share the same extractor, ejector and both can run reliably with the blue recoil spring. Also if you have an early model M&P 9mm you may want to consider an Apex FRE, had a friend who was getting some brass to the face with the conversion barrel (but otherwise running fine) and it was cured with the Apex FRE.
If you read through the forums, virtually everyone running the conversion barrel in their M&P has done so issue free. Those that have had issues tended to stem from green recoil spring and crappy range ammo.
Thank you very much.
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions, Inc. All rights reserved.