Ka-Boom

[noylj]

I have been working up various lead bullet loads in my EAA Witness Match .40. So far, looking only at accuracy at 25 yards, AA5 has been the best powder with 155gn L-SWC and 175bn L-SWC. While at the range, I loaded my first round of 6.1gn of AA5. Bullets was an NBC 175gn L-SWC with a COL of 1.1770. I have fired rounds up to 6.9gn AA5 without any signs of pressure or bulges. The EAA barrel definitely supports the cartridge. Any way, that first round KBd on me. The base plate of the magazine sheared off the body of the magazine and the front of the rubber grip panels tore loose from the frame. No damage to me. Went home and looked things over. Man, was my gun dirty. Except for the damage to the plastic base plate of the magazine and the front of the grips no longer having a "ledge" to lock the front of the grips to the frame, everything else looks completely undamaged. I used a brass brush to remove the remaining forward section of the case from the barrel. Cleaned up the barrel and it looks perfect.

I would have said that it was almost impossible for me to overcharge a round since I was dispensing with my ChargeMaster, but, if I am not to blame, then I would to consider that either .40 S&W cases can separate at random or that AA5 and the .40S&W have some mystical Mojo that can KaBoom at random intervals.

Broke down the remaining 9 cases and they all had 6.0-6.1 gn of AA5 in them. I ordered another RCBS Lock-Out die that day.

Edited October 14, 2010 by noylj

[justforfun]

Glad to hear no damage to you. From the manuals I have it doesn't look like you are even close to max for AA5. I would guess either bullet set back or double charge. The lock out die should help prevent a double charge, but you may want to check your case tension to ensure you aren't getting bullet set back. I have never used AA5 so I don't know how possible it is to get a double charge with it. Hope you figure out whats going on so it doesn't happen again.

[SLM]

I'm also going to guess double charged. And that brass looks like it's been hammered on pretty good already. Looking at the first picture it may have been cracked/splitting on the inside already. #5 is a very fine ball powder. I've played with it in 9mm Major a bit at over 7.5 grains with no primer issues. It's possible to get over 10 grains in a 9mm case without problems so 12 should fit in a .40 case easily.

Glad you and the gun are okay!

[G-ManBart]

Where does your brass come from, and can you tell what headstamp that one was? I couldn't quite tell, but it almost looks like it has "NT" which is often used for lead-free ammo. If it was just a case blowout, I'd expect far less damage than that....it sure looks like some sort of massive overpressure, but that's just a guess. R,

[granderojo]

The head stamp looks like Win NT to me. I don't know if that makes any difference.

Glad you're OK too. The last time I saw a 40 go Kaboom was a Glock and it did a LOT more damage to the gun that you had. It blew the mag and the trigger group out the bottom, blew the slide off and ruined the frame. The top of the slide at the front of the ejection port on both sides was peeled up and back (for a lack of better way to put it) at a 45 degree angle for about a 1/4-3/8" toward the front if the barrel. The shooter wasn't hurt. He thinks it was a double charge, not sure though.

Again, glad you didn't get hurt.

Edited October 14, 2010 by granderojo

[Jman]

Good to hear your OK.

A double is going to hurt you and pretty much junk the gun. Never seen a double not at least lift the barrel hood.

Very closely inspect your remaining .40 S&W brass. Especially near the base.

Wouldn't be surprised if we're looking at either firing out of battery or an old piece of brass.

Jim

[Sterling White]

There are those that have and have not! Welcome to the club. Make sure your powder bar hasn't changed as some powders spike with a few tenths more. It's an eye opener when it happens but I wouldn't get freaked out about it. It is most likely related to having too much powder. Least likely is that the case has been reloaded one too many times. You may consider a different powder that makes the powerfactor with less. Just a thought.

Edited October 14, 2010 by Sterling White

[Alaskapopo]

I have had a few case failures with the 40sw. No double charges but insufficient crimp on one. Wrong primers on another. Had a friend who has had 3 case failures to the point where he really damaged his Glock 35 the last time around working with clays powder. The 40 is not a forgiving round in this area unless you have a pistol that you can load long in. Like a 2011 with full case support.

Pat

[Pro2AInPA]

It sounds like you have your reloading technique down and the chances of a double are slim, especially since there wasn't a squib load in any of the remaining rounds.

My guess is bullet setback due to insufficient neck tension leading to massive overpressure.

Do you use a EGW U die?

[freakshow10mm]

AA #5 has been known to Accurate Powder Co. to let go in a .40 with an otherwise safe load. They can't figure it out, but it happens. The tech told me #5 is responsible for more KBs in the .40 than any other powder for no apparent reason.

[JeffWard]

AA #5 has been known to Accurate Powder Co. to let go in a .40 with an otherwise safe load. They can't figure it out, but it happens. The tech told me #5 is responsible for more KBs in the .40 than any other powder for no apparent reason.

That's comforting...

[freakshow10mm]

I know, right?

Sooo, don't use #5 for .40. Gotcha. That's what I gathered he was implying. I switched to WSF for all my .40 loads.

[FLSlim]

I've heard the same thing as Freakshow10mm. I like #5 in 9mm, but will not use it in the 40 out of caution.

[noylj]

It was a Win NT case. I can't think of any chemical or physical reaction that would make AA5 unsafe in a .40 and not in a 9 or .41AE. Does make me leery of the powder though.

There was no set back in any test loads, so unless that particular case had very thin walls, I just can't see set-back, but then I did not expressly test that particular case.

Here is a comparison picture if it loads:

Edited October 16, 2010 by noylj

[M-Bear]

It was a Win NT case. I can't think of any chemical or physical reaction that would make AA5 unsafe in a .40 and not in a 9 or .41AE. Does make me leery of the powder though.

There was no set back in any test loads, so unless that particular case had very thin walls, I just can't see set-back, but then I did not expressly test that particular case.

Here is a comparison picture if it loads:

Trust me I speak from personal experience. 40sw and AA#5 is bad juju.

Personally I will never use any AA powder anymore.

[goat68]

I have noticed that after several reloads, some brass will develop a visible line that will go part way around the case about 1/8" above the head. This is a weak spot developed from several firings from unsuported chambers and the brass being worked and thinned by resizing and firing. I'm not sure if this is a reason for the case going KB but I've tossed a bunch of loaded rounds with what I call "THE LINE". Somethimes the round will have an hourglass shape.

I experienced a KB last year about this time and I've since tossed a bunch of brass that has the apperance of looking old and gone to a GRX and supported chanber barrel. Not sure if "THE LINE" had anything to do with the KB but I have to guess it played a part. I haven't seen "THE LINE" since then but I chose to shoot 9mm minor for a year. Just now starting to load and shoot 40 again.

[Harmon]

AA5 seems to be present in a LOT of KB's...i dont know why but it just seems to be there when they happen.

[GrumpyOne]

I have noticed that after several reloads, some brass will develop a visible line that will go part way around the case about 1/8" above the head. This is a weak spot developed from several firings from unsuported chambers and the brass being worked and thinned by resizing and firing. I'm not sure if this is a reason for the case going KB but I've tossed a bunch of loaded rounds with what I call "THE LINE". Somethimes the round will have an hourglass shape.

I experienced a KB last year about this time and I've since tossed a bunch of brass that has the apperance of looking old and gone to a GRX and supported chanber barrel. Not sure if "THE LINE" had anything to do with the KB but I have to guess it played a part. I haven't seen "THE LINE" since then but I chose to shoot 9mm minor for a year. Just now starting to load and shoot 40 again.

The "line", as you put it, is not from firing in unsupported chambers. It's where the sizing die stops (for most dies anyway). It is usually nothing more than a visual thing....Section a case and find out for yourself.

The hourglass shape is also caused by the dies, undersizing the brass, then you bell/flair it and seat the bullet, which expands it back out. There is nothing wrong with the hourglass shape. There are more than a few threads about this here on the forum.

[noylj]

Grumpone:

I have seen many cases with a curve raised "edge" of brass that goes a bit less than half way around the case and matches the unsupported part of the brass from the feed ramp.

This brass came from somewhere and had to weaken the case.

There is no raised brass from sizing. There is an end to the burnished brass from the resizing die compared to the normal brass appearance. Every reloader must be able to recognize that. Also, the reloader need to learn that a "wasp waist" round is not an error but desirable.

However a raised ridge that you can see and feel is not desirable.

[GrumpyOne]

Grumpone:

I have seen many cases with a curve raised "edge" of brass that goes a bit less than half way around the case and matches the unsupported part of the brass from the feed ramp.

This brass came from somewhere and had to weaken the case.

There is no raised brass from sizing. There is an end to the burnished brass from the resizing die compared to the normal brass appearance. Every reloader must be able to recognize that. Also, the reloader need to learn that a "wasp waist" round is not an error but desirable.

However a raised ridge that you can see and feel is not desirable.

Where in my post did I say the line was raised ? Neither I, nor the Op of the post I replied to said it was raised, just that was a line. This has also been discussed many times on the forums. This is just where the die stops. I have never used a GRX, but I would assume that there never is a line, as the brass gets pushed all the way through.

I, too have seen many bulged cases (the so called Glock Bulge), but after sizing, they are no longer bulged. I suggest if you are seeing a bulged line on one side of the case after just one reloading, maybe where the case is unsupported, then that round may have fired out of battery by just a bit, and should be tossed. When I have one that is questionable (the line as it is), I run a knife edge over it, if I can feel it, it goes in the scrap heap. Very, very few of these....But, if you don't want to chance it, don't. Brass is too easy to get to worry about one piece here and there.

Edited January 30, 2011 by GrumpyOne

[Demax]

Few years ago I had a pretty similar situation. KB right after mag change. But ir was Magtech factory ammunition.

I wrote a mail to factory, they paid for DHL parcel and after some time a got a reply: detonation not in chamber.

Interesting, no signs of any hit on primer...

Edited January 30, 2011 by Demax