Interesting Unintentional Mag Change

[ChrisStock]

I was at the range with my new chrono yesterday testing all of my handloads, gathering data, making notes, and enjoying myself. My M&P .40 was a thing of beauty since the fantastic trigger job I had done a few weeks ago. The Arredondo mag extensions have also been functioning flawlessly to this point. I finished testing all of my personal ammo, and thought I would send a few rounds downrange of some factory ammo that my spouse had picked up for her concealed carry pistol. I needed some fresh 1X fired .40 brass anyhow.

Keep in mind, I had been running various loads of featherweight .40 that I had made up for the wife to shoot. Ammo squarely around the 125-130 PF. I chambered the first round of 155GR Federal Classic JHP, and sent it down. BOOM. Out comes the mag unbidden as my elbows and wrists protested mightily. "What was THAT?!?!" said the wife.

After regaining my composure and unpuckering my south end, I looked at the chrono: 1390 FPS at 20'. A 215 PF round, and this was NOT marked +P. I was VERY unprepared for the blast. I reinserted the mag, chambered another one and BOOM. 1397 on the chrono, and my mag has dropped onto the bench again.

I thought that maybe the excessive recoil was causing me to accidentally hit the mag release, so I reseated it, chambered another round, and sent one downrange strong hand only from the bench, watching the mag release carefully. I fired at the berm, with the exact same results, except the muzzle flip was almost 90 degrees. The mag unseated itself without me getting near the release.

This hasn't happened with any of the other dozen brands of factory that I have run through this pistol, and I am a tad concerned at this point. The wife's compact Taurus PT140 didn't drop the mag, but the recoil was way too much for her to get a followup shot in.

I examined the spent brass, and noticed nothing unusual, no signs of too much pressure. I then loaded up and sent a box of factory Blazer .40 downrange without a hitch, followed by 40 rounds more of my own standard .40 loads.

Has anyone encountered this before? Needless to say, I'll stick with the WWB and Blazer if I absolutely have to shoot factory ammo

Edit to add photo:

Edited August 26, 2007 by Lighteye67

[kz45]

was it the same mag everytime,maybe try another. just a thought

[ChrisStock]

Nope....2 different mags, and they functioned fine with other ammo after the fact.

[G-ManBart]

Wow, that's some HOT .40 S&W ammo! I just looked up the specs for Cor-bon ammo and their hot .40S&W lists a 150gr jhp at only 1200fps and their 10mm 150gr jhp at 1325fps. Hard to imagine factory .40 being hotter than factory 10mm ammo....especially Cor-Bon stuff which is always pretty hot. I checked Federal's website and they don't list the Classic ammo now, but their 155gr Hydra-Shok load is listed at 1140fps. It's hard to imagine how the stuff you have could have been loaded to be 250fps faster intentionally. I'd love to know how that happened, but I sure wouldn't shoot any of it in my guns!

[revchuck]

Don't shoot any more of that ammo! I've got some, and the batch I have chronos about 1140 fps (4" Steyr M40), which is about right. Yours is WAY too hot. Call Federal and tell them - they'll want to know and will make it right.

[Chuck Anderson]

There is some ridiculously hot 155 gr ammo out there. The SXT ammo that CDNN is selling has destroyed two Glocks that I know of and runs about the same speed. If the ammo is going almost 1400 feet per second, it's clearly loaded wrong. Stop using it, it's unsafe. Either destroy the ammo or call Federal and see if they'll replace it. The gun you're using isn't designed to handle ammo that hot. It could be unlocking early and sending gas into the mag or the whole gun could be flexing too much. I asked one of Federal's reps about the SXT ammo and he said there is no +P spec for .40 so there is no way it should be that hot.

[revchuck]

Lawman - If you're talking about the Winchester Ranger ammo that CDNN sells, I've chronoed that too - did a bit of research looking for a .40 S&W carry load. It ran 1199 fps from the Steyr. Pretty feisty but controllable, and it's the one I ended up choosing.

This isn't to say that some of that ammo might not have been way too hot as well. I'd be surprised if it were, but then I'm surprised about the Federal stuff too.

[ChrisStock]

Here's a pic of the culprit:

cartridge model # is XM40SWB 155GR JHP

I may call Federal tomorrow and inquire as to what it is tht I am in posession of. If it was Corbon or Magsafe, or any of their ilk, I would have expected one that hot. I had already come to the conclusion that I wouldn't be shooting this stuff off, and that it was a painful $20 lesson.

I did find a link about this super hot load here, but not much else of interest. I'm digging through federal's website now, and will post any furhter info. Able Ammo has this load listed at 1140FPS, but what I have is considerably hotter. Interesting stuff.

[WillM]

At a local match a few months ago, I was at the end of a course of fire when I experienced a loud kaboom!, got a face full of hot gas and small bits, no blood but glasses were smeared. I'm standing there going wtf and ready to rack the slide when the ro says stop!. Mag laying on the ground, follower and spring gone and bolt locked tight, ejector and ejector spring gone too. We finally get it pried open and case looks like it tried to eject through a 1/4" opening where barrel didn't meet chamber face of the CZTS .40 I was shooting. Primer was flat, obvious pressure signs.

Gee, those are some hot reloads you're shooting everyone says. No, I'm shooting WWB. No, you must have put a hot reload in there. No, I don't even reload .40. Well I was a new action pistol shooter and now I do reload .40 and I had reloaded mass quantities [10's of thousands] of shotshells and some .45 over the years and never experienced anything like that. Factory loads are not perfect despite what some say. I didn't bother contacting Winchester but I do have the shell case but why bother, no one was hurt and stuff happens and with a new extractor and some minor file work the gun works fine.

[Chuck Anderson]

Lawman - If you're talking about the Winchester Ranger ammo that CDNN sells, I've chronoed that too - did a bit of research looking for a .40 S&W carry load. It ran 1199 fps from the Steyr. Pretty feisty but controllable, and it's the one I ended up choosing.

This isn't to say that some of that ammo might not have been way too hot as well. I'd be surprised if it were, but then I'm surprised about the Federal stuff too.

I've seen it chronoed out of two separate guns at 1350-1400 fps and the guns were substantially damaged. As in slides not able to be retracted and the magazines blowing out the bottom of two different Glock 22's. My guess is there are some wildly different loads in some of the guns. I've also talked to several different officers from other agencies shooting 155's who've received similar results, 1300+ fps velocity. Not sure why, don't know if the powder is detonating instead of burning in some rounds or what. I just know there is no chance I'm ever putting a 155 into any gun I own.

[ken hebert]

I've shot some of that same Federal 155gn, and it's HOT!!! We got a pretty good deal on a few cases at the gun shop, and I thought what the heck, so I picked up some. We're retailing it for a little over $9 a box. Ran a mag through my SIG229 and DAYUM!! Talk about +P+++ pocket rockets. No thanks. I'll stick to .500S&W for that kind of abuse.

[Glockster35]

Wonder why the box says not for LE use...is that an indicator somethign is wrong with the ammo?

[racerba]

Wonder why the box says not for LE use...is that an indicator somethign is wrong with the ammo?

I was wondering that myself. I've seen "Law enforcement use only" but not the other way around.

[big_kahuna]

cartridge model # is XM40SWB 155GR JHP

I may call Federal tomorrow and inquire as to what it is tht I am in posession of. If it was Corbon or Magsafe, or any of their ilk, I would have expected one that hot. I had already come to the conclusion that I wouldn't be shooting this stuff off, and that it was a painful $20 lesson.

I did find a link about this super hot load here, but not much else of interest. I'm digging through federal's website now, and will post any furhter info. Able Ammo has this load listed at 1140FPS, but what I have is considerably hotter. Interesting stuff.

Please do contact Federal about this. I'm eager to hear about their response.

My first impression that the ammo was loaded out-of-spec. If Federal let this box out, consider that there may be hundreds (or more) boxes of "hot" ammo floating around waiting to be used. It's obviously in their best interest to investigate this issue and make it right... they'll try to minimize their liability (I'm sure they'd like to avoid having injured customers who might pursue hostile litigation). They'll do the right thing, even if only to avoid the risk.

[ChrisStock]

I left a voicemail with Federal yesterday, as I was unable to get a live person on the phone. I'll post any further info that they care to hand off to me regarding the super hot box of JHP lightning.

[aggunner]

We got a bunch of this stuff at work and I grabbed a box to test out and holy sheet. I ran a mag through a full size M&P and my wrist was hurting.