STI 2011 .40 kaboom

[dauntedfuture]

So im out shooting my 2011 .40 today. 170 lead Precision molly bullets, 4.4 tightgroup, tula SP 1.230 OAL, crimped to .419 and things got bad. All loaded on a 650 WITHOUT a powder check station that will be on order tonight.

Started wtih 4.0 = 858

4.2 = 900

4.4 925 fps

I had already shot 20 of the 4.4 and realised that this was too slow so i burned the rest of the ammo. I was shooting strong hand only and the pistol let go. I was not hurt. Recoil was not excessive. The case blew out the bottom and the primer was no where to be found. The round on the top of the magazine was set back to 1.112 OAL. The case that let go was a federal. I did not have to "pound" the case out with a squib rod.

I see two possibilities:

double charge of powder would fit in the case or something along those lines.

The bullet set back into the case as i dont think i had and real crimp at all as it turns out. I fould not push the bullets back into the case by hand.

All the primers look fine and i am well inside the max for the powder. I am confident that the pistol did not fire out of battery. There does not appear to be any damage to the pistol other than a total loss of the frame and trigger.

Anyone have any other ideas?

I consider myself luckey that i was not hurt.

Edited November 15, 2011 by dauntedfuture

[warpspeed]

Lucky indeed.

Looks like the case just let go. Are these known once fired or range pick ups ?

[Skydiver]

How did you eliminate plain old case failure as a possibility?

[OzzieF]

Only other cases ive seen with the same blowout on the bottom of the case was from an open 9mm major gun.

Possibly over loaded and case failed.

[Merlin Orr]

Bummer about the blowout but....... your fingers are still all there......

[dauntedfuture]

It was range pick up brass. Likley once fired federal in all likleyhood as there is lots of federal agencies shooting the stuff here.

[warpspeed]

It was range pick up brass. Likley once fired federal in all likleyhood as there is lots of federal agencies shooting the stuff here.

More likely someone loaded up some +p stuff and shot it from a stock Glock.

I would not load mystery brass at major pf but that is just me.

[Action Pistolero]

Yikes!

I've had one case head separation and it was quite mild compared to yours. It was a 40 loaded minor in a Para LDA. Blew the case head down through a loaded mag and knocked out the base pad. Left the rest of the case in the chamber. Other than looking like a reverse raccoon I was fine. Another reason to always where glasses. This was a friends gun and loads. Needless to say, he got 1k pieces of new Starline for Christmas that year.

Like Warpspeed said, never load unknown brass. Especially 40.

[dauntedfuture]

Humm. Never thought about that. Lots of glock shooters around these parts. I have however ordered some dillon powder checkers to keep my mind at ease in the future.

[a.roberts]

I'd bet against a double charge.

If it was, I think you'd be looking at a paperweight, instead of replacing your grip and trigger.

Do your loaded rounds have that "coke bottle" shape to them?

[dauntedfuture]

No coke bottle shape.. Hornady dies. Round on top had some signifigant set back. 1.1 or so, not so far under "normal" length with a moderate charge. Im not sure if the explosion set the bullet back in the case or the recoil. Im for sure going to make sure i get better crimp in the future to rule out that possibility. Im also not enamored with TG, might look at something else powder wise too. Suggestions?

[a.roberts]

You have enough crimp. All "crimp" does is remove the belling/flare.

What you need is more/tighter sizing.

Here's a post from another thread that explains it well.

I don't use a U-Die, I use a Lee Bulge Buster and get the coke bottle shape, but YMMV.

For .40, I consider an EGW U-Die ("Undersized-Die) not only an essential piece to salvage as much Glocked-brass as possible, but an absolute safety requirement.

.40 runs at a much higher pressure than say, a .45 (about twice as much). What the U-die gives you is 1/1,000" undersizing on your brass. It was long argued that the only difference between a standard Lee die and a Lee/EGW "U" die was that the U-die was surface-ground to allow it to size further down the case than a standard die. Not so. The owner of EGW (name escapes me at the moment) came on here once to explain that the unique feature of the U-die is that it is made to his specifications of 1/1,000" undersized than usual .40 resizing dies.

Why is this important? Because case resizing, not crimping, prevents set-back.

Due to the inherent higher pressure associated with the .40S&W round, and it's minimal case capacity, ANY set-back of the bullet into the case causes pressures to spike non-linerally. We're talking....KA-BOOM!-level pressures. With the undersized case dimension provided by a U-die, the bullet base is forced into the undersized brass by the press and results in the classic Coke-bottle round. You can SEE the base of the bullet through the brass. It would take something akin to a hammer blow to push that bullet further into a case. Feed failures that slam the cartridge into the edge of the chamber are exponentially less likely to result in set-back.

*Short version: If you're loading .40, get a U-die. It's the best $25 insurance policy you'll ever buy.

[Skydiver]

What is your recoil preference: "push" or "snap" ?

For "push", I found Silhouette loaded at Major PF was very nice. It meters amazingly well. Unfortunately, I couldn't stand all the "WAP crap" that I had to clean up inside the gun. I'm using Competition now which is much cleaner.

Hopefully others can chime in for powder recommendations.

[Aircooled6racer]

Hello: I think it was an overcharge that blew out the case. It may not have been a double charge but just more than normal power factor. Glad to see you are ok Thanks, Eric

[dauntedfuture]

Well for what its worth a UCD die is in the mail, and more crimp for good measure. Is it that easy to get bullets to sey back in the case?

[ihatepickles]

My guess is bullet setback. Adding more crimp is never the answer for this. The .419" crimp is already too much, cranking it down more is a bad idea. To prevent setback you need correct case sizing. If brass has outlived it's usefulness it won't size properly regardless of undersized dies and such. No amount of crimping or factory crimp dies can fix worn out cases.

With a .419" crimp, you're taking a .401" sized lead bullet and squeezing it down to .398". To crimp correctly, you take the bullet diameter (.401" for your lead molys) and add the thickness of the case walls. Most cases this this is .010"-.011" (which must be multiplied times 2 since there's 2 case walls), I generally add .021"-.022" to the bullet diameter. In your case I'd aim for .422" of crimp. By overcrimping your rounds, you're smashing the lead bullets down to a smaller diameter and making the setback much more likely to occur.

Reloading jacket bullets are more forgiving, they deform much less with slight errors in die setup. Lead is cheap and can shoot really well, it just requires a bit more attention to details. I hope that helps.

[dauntedfuture]

.419 is the mouth dia of the sized case and its the same dia as with a bullet in case therefore i believe there was/is no crimp. I would know if the case is getting crimped into the bullets and its not. Pulled the rest of what i had and you can only make out the faintest mark from the crimp.

[PKT1106]

That is interesting. I run 4.5 of TG in my XDM with 180s at 1.125" with minimal crimp for major and have never had any signs of over pressure. Hodgdon lists 4.7 as max charge with 1.125" OAL. Looks like either a bad case or overcharge, leaning toward bad case.

[ihatepickles]

.419 is the mouth dia of the sized case and its the same dia as with a bullet in case therefore i believe there was/is no crimp. I would know if the case is getting crimped into the bullets and its not. Pulled the rest of what i had and you can only make out the faintest mark from the crimp.

I'll try and state my case again and then you're on your own. Taper crimp, which .40 S&W uses, is not done to secure the bullet. It's only purpose is to remove the bell on the case mouth. The crimp shouldn't be tightened down, it just needs to return the brass to it's original (non-belled) shape.

A .401" bullet, plus .011", plus .011", is .423".

If you start at .419", minus .011", minus .011", you now have a .397" bullet.

You are smashing your bullet by applying too much crimp. I've got no stake in this, it's not my gun or my hand. I'm just trying to pass along some hard earned knowledge. A .419" crimp is too much, the bullet will setback in the case.

[kalaur]

If you start at .419", minus .011", minus .011", you now have a .397" bullet.

You are smashing your bullet by applying too much crimp. I've got no stake in this, it's not my gun or my hand. I'm just trying to pass along some hard earned knowledge. A .419" crimp is too much, the bullet will setback in the case.

Not quite. Yes the bullet may be smashed *at the mouth of the case* down to .397, but that generally doesn't cause anything but accuracy issues, IF even that. A .419 crimp is fine, given it removes the flare from your cases, and does not cause accuracy issues. Saying .419 crimp is too much is like saying loading 1.200 is too long.

I do agree with ihatepickles in the statement that crimp is NOT used to secure the bullet in the case. Using crimp to secure the bullet in the case is a crutch and will probably end up causing an issue at some point (such as if you get a case that is too short to get that crimp).

I do find this KB interesting, I load a lot of FMJ 180gr bullets with 4.8-5.0 of titegroup (at 1.190 OAL), and (knock on wood) haven't had any issues yet. It really seems to me like this may have fired slightly out of battery, or if something was preventing the barrel from fully locking up. The back of a case should not blow out on a fully supported barrel.

Edited November 15, 2011 by kalaur

[leas327]

I agree with pickles. I crimp my lead at. 421. That is the most crimp my bullets will take. Any more and it starts to size down the bullet. You stated that you pulled the rest of the ammo. Measure a new bullet and measure one you pulled to see if there is a difference.

Undersize lead can cause sever leading quickly. A leaded barrel will cause high pressure.

Edited November 15, 2011 by leas327

[dauntedfuture]

Humm. Ill take a look when i get back from the field. When i size the cases in the hornady dies the case mouth is .419 and, as it turns out that what i brought the cases back to so the cases did not start larger than .419 so im confuced with the "you are smashing your bullets with crimp" comment as that where the cases start before and after crimp.

The bullets are all in good shape after pulling as that is to say no shaving and no real marks. The bullets were fairly easy to pull with that hammer thing. Ill measure diameter them when i get back home.

I did not think about an out of battery incident. I have no idea at this point where the brass came from but it was more than likley range pick up factory stuff, possibly once fired but un likley. What might cause an out of battery incident? I have another frame on order, a Lee U die (might not need it) and dillon powder checkers all for good measure. Id hate to do this again. Only other thing that i can recall is that i had a few light primer strikes previous so i re cocked the hammer and things went bang (not boom). On the round that let go everything was working ok as far as i know well.. up to a point. Oh, no leading that i can speak of and accuracy was good.

Edited November 15, 2011 by dauntedfuture

[bkeeler]

Glad your ok. I am going with bullet set back causing high pressure and the case failing due to high pressure. I think there are more bullet set back problems that cause these failures than over charge/double charges. I had it happen years ago and come to find out I had a bad resizing die!

BK

[leas327]

When i size the cases in the hornady dies the case mouth is .419 and, as it turns out that what i brought the cases back to so the cases did not start larger than .419 so im confuced with the "you are smashing your bullets with crimp" comment as that where the cases start before and after crimp.

The bullets are all in good shape after pulling as that is to say no shaving and no real marks. The bullets were fairly easy to pull with that hammer thing. Ill measure diameter them when i get back home.

The case can measure .419 before the bullet is seated, you could seat the bullet and it could get pushed out larger, then a crimp die that is tightened down too far can make it .419 again. The bullets I pulled that my crimp die swaged down looked normal to my eye but a micrometer told a different story.

[wide45]

I'm thinking setback or overload. Takes a lot of pressure to blow out the primer.