Had a KB! How do YOU properly check case crimp???

[Neutered10mm]

Long story short, completely destroyed my G27 when I had a case head/web blowout at the 6'oclock position. This was round #10 in a 15 round magazine and the remaining 5 rounds had varying degrees of setback caused by the explosion. Happy to report I'm typing this with all fingers intact, although very sore!

Not sure exactly how this happened as my crimp has been sufficient for my prior 500+ rounds without incident. When setting up the press, I initially checked OAL to be at or within .005 of 1.130 trying not to exceed 1.135 due to how unsupported 1.140 looked and how it goes against everything I have seen printed in manuals. After I got the proper setback, I setup the crimp die with unprimed brass and kept turning up the crimp until it took an excessive amount of hits with it in the breakdown hammer to get the bullet to unseat.

Is there another way to test the crimp? I'm fairly certain this occurred due to an oversight on my part when running my son through the process to show him exactly what I have been tinkering with (he's fascinated with the different cases and bullets). I let him run his own dummy rounds and may have forgot to reset the dies. Dumb I know ... I don't need a lecture, I'm fairly certain this is one event I will never forget and most definitely will learn from.

The remaining 40 rounds will be broken down and assessed and the crimp die will be recalibrated, but I was wondering other than testing crimp with the breakdown hammer on an unprimed case, how do YOU check for crimp strength???

 

[MtnCreek]

IMHO, you may have a neck tension issue. This is a .40, correct? Crimp should not be required to hold the bullet in place. Also, I wouldn't judge my neck tension by it's ability to hold the bullet in place during a KB.

Edit: I push the bullet against my bench. If it measures the same after, it's good to go.

 

[Mike 27]

Your crimp should only take the bell out. A heavy crimp is not required on semi auto pistols. How many times have the cases been loaded? What components, and charge did you run? Pull down the remaining and check the powder weight. Glocks have the un-supported chanmber at the feed ramp, and it sounds like that is what blew out. Glad to hear you have all of your digits, and ok....I have to think this was not a crimp issue unless you really overcrimped. The mouth should be .423 per the SAAMI drawing.

 

[Neutered10mm]

Yes, I'm reloading .40

Yes, I also had checked that (measure, press on bench, remeasure) after initial setup and did so before putting in the hammer for breakdown. The more and more I mull this over, it comes back to me forgetting to recalibrate the die after showing my son how the press operates (walked him through an entire setup routine).

I'm just curious if anyone makes a special tool specifically for this purpose. Something I can put in my QA/QC routine. As it is WAS, I did initial setup of each die station, measured the powder charge on the first 5 rounds and then every 5th round. Each round of each 50 produced was then checked for OAL to ensure they were within spec. As it IS now, I'm going to add a nose press of EVERY round and recheck OAL before they are boxed for the range bag, NOT just on initial die setup.

 

[MrCountyCop]

Glad you still have all your digits!!

 

[Walkalong]

Yep, as posted by MtnCreek, neck tension holds the bullet in .40. Crimp is just to remove the bell or a hair more so it will fit the chamber.

Try the press a round against a hard surface to see if it moves trick. If it does, you do not have enough neck tension. If so, your sizer is to big, or your expander is too big, or both. Load a couple of rounds without using the expander and see if you have adequate neck tension. If you do, the expander is too big, or you are way over expanding. You can turn the expander down a couple of thousandths and try it again. RP brass is also notorious for being thin and having inadequate neck tension when thicker brass does fine.

No amount of crimp can make up for poor neck tension in .40. What bullet and charge?

 

[243winxb]

Plated Bullets?

 

[Neutered10mm]

@Mike 27 ... brass was once fired from a police range pickup. Brass was then tumbled in a Thumblers Tumbler with SS media, 1 gallon of water, Lemishine & Dawn. After drying, bases were lubed, run through Lee De-bulge kit and then through each station of my setup. Station 1 = deprime/resize, Station 2 = prime/bell, Station 3 = powder, Station 4 = powder cop, Station 5 = seat/crimp. The reloader is a Hornady LNL AP and the dies are Hornady.

 

[Neutered10mm]

Bullets are Ranier 165gr plated double struck (hollow point only because they had a great deal of $104/1,000 vs. $122/1,000 otherwise I would opt for flat nose). Brass is once fired police range brass, 85+% federal, some Winchester. Powder is Hodg TightGroup @ 4.7-4.9gr & primers are CCI #500's.

 

[Neutered10mm]

I'll get pictures up later ... pressure involved is thoroughly impressive! Thanks for the "glad you have your digits" comments! Was my wife's first time at the range in 10+ years as I'm trying to get her into the hobby as well so we both can enjoy it ... needless to say I'm extremely greatful it went off in my hands and not hers!!!

 

[chaplain 31]

question...

I don't consider myself an expert on this, but I'm having a hard time understanding how crimp could cause this, unless it was so light and the case tension was not right that it allowed the bullet to be pushed back into the case during chambering. I've shoot thousands of rounds of "lightly" crimped 40 with no problems of any kinds. Is there a possibility something else caused this.

 

[243winxb]

Thats the problem > plated bullets. Or double charge of powder. Hodgdon website-

This data is intended for use in firearms with barrels that fully support the cartridge in the chamber. Use of this data in firearms that do not fully support the cartridge may result in bulged cases, ruptured cases, case-head separation or other condition that may result in damage to the firearm and/or result in injury or death of the shooter and/or bystanders.

 

[Neutered10mm]

going down to the reloading room right now to bust out the calipers ... the remaining 5 rounds in the mag have their bullets setback quite a bit. This leads to a massive pressure increase from what I have read on the subject. Doesn't help that the .40 is already a "hot" load right out of the box with pressures routinely in the 33,000 psi range. According to multiple sources "Hirtenberg Ammunition Company of Austria (at the request of GLOCK, Inc.) determined that, with a .40 caliber cartridge, pushing the bullet back into the case 1/10 of an inch doubled the chamber pressure." That being said, I'd care to guess just my eyeball, at least 2 of the remaining 5 bullets in that mag exceed this (my guess is explosion rocked them hard enough to cause setback). The entire magazine nearly blewout (dropped an inch) and the polymer casing around the metal inner shell of the magazine fractured in MANY places. The frame cracked in 3 places, etc ... will get pictures up soon.

 

[Neutered10mm]

@243winxb ... how would bullet type cause this? Please elaborate.

 

[Neutered10mm]

I'm suspecting bullet setback at this point based on the remaining 5 rounds ... I don't suspect the components ... hell, if anything, I'm impressed at how well everything held together with the case.

 

[biogenic]

I don't consider myself an expert on this, but I'm having a hard time understanding how crimp could cause this, unless it was so light and the case tension was not right that it allowed the bullet to be pushed back into the case during chambering. I've shoot thousands of rounds of "lightly" crimped 40 with no problems of any kinds. Is there a possibility something else caused this.

I agree. Sounds like too much powder entered the casing or a bad piece of brass. Did you visually inspect all the brass?

 

[Mike 27]

I saw somewhere on a spec sheet that the Lee bulge buster was not to be used on 40/10mm because of the unsupported chamber. I would have to dig for it and have to go to work so can't right now. Maybe one of the smart guys knows. I almost bought it for my 10mm G20 until I read this. Maybe it has something to do with it especially at the location on the case failure. Taking the glock bulge out may be your issue. Check their website for it, but I am almost positive it says not to use it for the .40 or the Glock.

 

[Neutered10mm]

I don't have a case feeder, so I manually feed each round, prior to feeding, I inspect the brass. This is a 2nd check as I do a visual inspection prior to de-bulging. Fairly certain the brass isn't to blame and I my press routine is this: press down, hold, inspect powder cop, inspect powder measure (ensure full travel), inspect visual indicator of the primer rod ... leading to me to believe my powder charge was in spec as well.

 

[918v]

You keep saying the ammo remaining in the mag exhibited setback. But it had not yet been chambered. So how did the setback occur?

Not sure exactly how this happened as my crimp has been sufficient for my prior 500+ rounds without incident. When setting up the press, I initially checked OAL to be at or within .005 of 1.130 trying not to exceed 1.135 due to how unsupported 1.140 looked and how it goes against everything I have seen printed in manuals. After I got the proper setback, I setup the crimp die with unprimed brass and kept turning up the crimp until it took an excessive amount of hits with it in the breakdown hammer to get the bullet to unseat.

This is not the way to adjust a crimp die. What you did there was dig the case mouth into the bullet, but at the same time ruined case tension on the bullet. It's like this: if you try to force brass into a non-existent crimp groove, the case walls below the case mouth will collapse sway from the bullet. What you end up with is a round being held together entirely by the crimp, and not by brass tension.

I have seen people write they applied so much crimp, but they can spin the bullet in the case with their fingers. They wrote they continued to add crimp but it didn't help. That is exactly what you did. You belled too much and crimped too much thinking the crimp is what holds the bullet in place.

To properly adjust the crimp die you screw it down to remove the visible bell from the case mouth and no more.

 

[Striker Fired]

If you were crimping too tight, it is possible that the mouth of the case that blew slipped into the throat.If it does that the bullet gets wedged and the pressure skyrockets. Take some pics of the remaining rounds and let us see your crimp and how the rounds looks.

 

[Neutered10mm]

918v ... this is NOT the case ... pictures will show no excessive crimp. In the quoted text, I forgot to mention that if at any time I noticed the bullets were creased by the crimp, I backed off. My bullets are being held in by neck tension and perhaps I'm misusing the term "crimp". My crimp isn't reverse belling and literally grasping the bullet ... I made certain this wasn't the case. Again, the pictures of the remaining 5 rounds will tell the story I'm sure.

As for how the remaining 5 got setback ... I'm sure 50,000+ psi being forced upon the bullet nose (hollow point remember) and then rocking them forward would have such an effect. Yes they weren't chambered, but they were certainly placed under an EXTREME amount of pressure from the prior round exploding just above them. Keep in mind, the blowout was at the 6 o'clock position, shooting the pressure down the feed ramp and directly at the rounds below.

 

[biogenic]

I don't have a case feeder, so I manually feed each round, prior to feeding, I inspect the brass. This is a 2nd check as I do a visual inspection prior to de-bulging. Fairly certain the brass isn't to blame and I my press routine is this: press down, hold, inspect powder cop, inspect powder measure (ensure full travel), inspect visual indicator of the primer rod ... leading to me to believe my powder charge was in spec as well.

You mention leading.... How do you get leading when you use fmj or plated bullets ?
Glock specifically warns against lead bullets. Did you use lead ? If you did, the obstruction caused by leading could result in blowing up your gun,especially Glocks

 

[PO2Hammer]

The best way IMO to check for set back is to make up several dummy rounds (no primer, no powder) with the same components and die setting as your load.

Load them into the magazine and cycle them in and out of the gun by pulling the slide back and letting it fly forward.
My plated .40 loads will set back less than .005" after three times through the gun.

Bullet tension is the key to preventing set back. With plated bullets in .40 I use the Lee universal expander die, it's a conical flaring tool that puts just a little flare (.003"-.005") on the case mouth without opening up the 'neck' area of the case. That lets the bullet do all the expanding and increases the case's grip on the bullet.

Then just use a taper crimp die to remove any trace of the flare.

 

[243winxb]

To Much Crimp??

@243winxb ... how would bullet type cause this? Please elaborate.

The soft lead bullet core can be swaged smaller by taper crimping to much. The cartridge brass can spring back, but a lead bullet will not. This leaves little neck tension to hold the bullet. If a jacketed bullet is swaged dowm more than .005" the lead core becomes loose also.

We, at Rainier Ballistics, recommend using lead bullet load data when loading our bullets. There is no need for adjustment when using lead bullet load data. Our bullets are jacketed using an electroplating process and are softer than traditionally jacketed bullets; hence the recommendation to use lead bullet load data. If you only have access to traditionally jacketed load data, we recommend a starting powder charge directly between the listed minimum and maximum load. A roll or taper crimp may be used with our bullets; do not over crimp.

As in most KABOOMs, we may never know the real cause.

 

[Neutered10mm]

biogenic ... leading and leading ... don't you just love the English language

In context, I was led to believe ... leading me to believe. Also, if you have any press experience or work in the graphic design field, leading is also the space between lines of text because movable type from the 16th century up until digital presses were invented used lines of lead to gap the font "slugs"