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

[bbuddtec]

yep i was going to go w/ oal...

 

[918v]

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.

If you didn't overcrimp, then you may have belled too much. If you did not bell too much, then this:

A while back I did a crimp test. At the same time another person in another part of the country did a crimp test. He claimed he was able to stop bullet setback by adding crimp. The proof was in the drycycling of the pistol. My test showed no such improvement in bullet retention.

I used a .450" plated bullet to prove my point. The undersized bullet set back no matter what the crim was set to. I even cranked the die down so much the round became bottlenecked. The crimp did not hold the bullet. My .452" bullets did not move in the case with a light amount of crimp, even after 10 chamberings.

It could be you have a crappy batch of undersized bullets and that is why you are seeing setback. No amount of crimp will compensate for a lack of bullet diameter.

 

[LiveLife]

First, welcome to THR!

Second, glad you are OK and nobody got hurt!

Third, thanks for posting/sharing your experience as I am sure it may help countless others prevent a KB.


Now, to do the "root cause analysis" of the KB ... and we are ruling out a double charge, right? Then what's left to cause a KB are the combination of the following:

- Over charge of powder (Weigh several powder charges to verify. As others posted, Rainier suggest you use lead load data. There is no current published lead load data from Hodgdon for Titegroup)

- Bullet seated too deep (Load several more rounds with the same bullet and measure the OALs. For 165 gr JHP Rainier bullet, OAL should be around 1.125")

- Too much crimp that may have cut into the plating caused plating separation (For .400" sized Rainier plated bullets, no more than .420" taper crimp should be used - any more and case neck edge may cut into the plating. Measure the taper crimp of several loaded rounds and pull the bullets to see if plating was cut into)

- Weakened brass case (This would be harder to determine as once-fired brass can have different conditions of brass depending on the pistol/barrel/powder/charge that was used on the initial firing)


To prevent another KB, I would carefully retrace every step of your reloading procedure to identify where the problem area(s) were and add quality control (QC) steps as necessary.

 

[Bovice]

A little too much Titegroup and some setback will blow up your gun in short order. What most people don't realize is that 9mm operates at nearly the same pressure as the .40, so it being "high pressure" and in a class of it's own in this respect is wrong. It's possible that you had some setback, but we'll never know for sure. The best plan to proceed is a couple of things.

A blowout at the 6 o'clock sounds like you had a bad piece of brass. Over-bulged cases which are resized will have a sharp ridge near the case head where the slack from the bulge has been taken up. If you see this, disassemble the round and throw the brass away. A good round will have the coke bottle/wasp appearance. Anything else should be suspect.

A safer way to apply your taper crimp is to do it in another step, separate from seating. Seating dies can easily crimp too much and ruin your neck tension.

 

[Neutered10mm]

I just took some video of my breaking down the rounds, taking some measurements, making a new dummy round and breakdown, etc. Here are some interesting findings ... the rounds in question had a crimp line in the bullet, but not sever enough to break through the plating ... think how you get sock lines in your skin if you are dehydrated, or pillow crease lines on your cheek ... nothing excessive, but then again, I'm hear for advice, I'll post pictures and assume nothing.

On my built dummy, no line and retained damn well (took 7-8 fairly good blows). The "suspect 5" were broken down in 2-3 blows (only took down 3 of them). I'm downloading the pics and vids now ... will post in a few minutes.

 

[rcmodel]

IMO: I would not use a very fast powder like Titegroup in .40 S&W on a bet.

You are skating on thin ice at near max loads, even under the best of circumstances.
Add in bullet setback, or a weak case and you are gonna blow up.

I'd switch to a slower more forgiving powder that fills the case to the base of the bullet.
It is not as critical, even if the load becomes a compressed charge due to set-back.

rc

 

[joneb]

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.

Is there a more precise way to test case tension ? or are we stuck with "that seems about right" I was thinking of a gauge to measure the amount of force needed to move the bullet, and is there a standard this measurement could be compared to ?

 

[Neutered10mm]

I will more than likely take that advice! I was looking at the Hodgdon for my load data and the "hottest" load I have logged is a 4.9 ... 4.7 starting, 5.1 max ... figured I was safe with a 4.9 personal max. My first 150 rounds were loaded to 4.7 and they ran cycled fine, were snappy, but not excessive. The last 400+ rounds were 4.8-4.9 ... it's entirely possible a case may have been charged to 5.0-5.1 as it wouldn't have raised the Powder Cop a describable amount.

Looks like I will have to attach these in batches since there is a 4 attachment limit per post :banghead:

 

[Neutered10mm]

My hands:

Left hand between the thumb main knucle and hand joint ... that meaty pad ... got the smack of it's life with the mag release. The pressure was great enough to explode the mag release mechanism in half, sending the other half (right side) out of the gun and the left side (mag release button) into my thumb.

Right hand ... trigger finger was abused by the Glock's right trigger side as it exploded outward.

 

[Neutered10mm]

Gun body is pretty FUBAR!

 

[Neutered10mm]

hmmm, this isn't going to come out easily was my first second and third thoughts ... I was right ... took a little more beating with a hammer that I was comfortable with.

My lucky horseshoe?

 

[Neutered10mm]

Extremely grateful I'm typing this with all 10 digits!

 

[MtnCreek]

You can rule out bad brass or anything else that wont raise pressure dramatically. Judging by the head of the fired brass (exploded brass), I'd say you were in excess of modern rifle pressure.

 

[Mike 27]

Ok I found the Lee bulge buster disclaimer, and this sounds like it could have been the issue. After seeing your pics I am glad to hear you are ok.

From the Lee Website:

"Glock Cases: We do not recommend "fixing" cases fired in pistols with unsupported chambers, because there is no way to make them safe once they have bulged. The case wall is thinned where it bulges, and resizing the outside of the case back down to the correct diameter does not restore the case back to its original thickness. If this case is fired in a pistol with an unsupported chamber again, and this thinned section of brass happens to line up with the unsupported part of the chamber, there is a high probability that the case will rupture."

Just some food for thought,

Mike

 

[Neutered10mm]

As I said before, my QC process involved measuring OAL and shooting for 1.130 +/- .005 as acceptable. I would setup the press, powder measure the first 5 rounds till they are consistently throwing my goal, then checking every 5th round after that. Once I get 50 produced, I'd check the OAL again before boxing them up. I loaded 2 G22 mags (15 rounds) and 2 G27 mags with the Pearce Extended Baseplates (+1), allowing me to load the entire box in 4 mags. After the KB, I unloaded the remaining 35 rounds (remember, this happened on round 10, 5 remaining in the exploded mag) and put them in the same box as the remaining 5. Here is a picture of one of the suspect rounds (haven't pushed on the bullet yet to test, will do so after posting this) measured.

Compared to the of the 5 survivors!

 

[Neutered10mm]

@ Mike 27 ... same thing is printed on an insert that came with it ... have heard from numerous reloaders on numerous forums that reload .40 without incident and this disclaimer is merely a warning to CYA in case I were dumb enough to sue over something like this. I accept this is fully my fault, I'm now just trying to find out why.

 

[Mike 27]

I considered picking one of these up for my Glock, and saw it....Not sharp shooting you, thought it might be helpful....


Mike

 

[Neutered10mm]

Thanks, I appreciate you taking the time to post what you had found on Lee's site. Lee includes the same disclaimer in the kit and even Hornady advises against reloading already shot .40 ... perhaps this will lead me to either increase or decrease my replacement caliber. Currently I'm considering a G23 with a 9mm conversion barrel and not reloading since 9mm is affordable ... still on the fence as I'm admittedly "gun shy" with anything coming off my loader from here on out until I can nail down the cause and address it.

 

[918v]

"Glock Cases: We do not recommend "fixing" cases fired in pistols with unsupported chambers, because there is no way to make them safe once they have bulged. The case wall is thinned where it bulges, and resizing the outside of the case back down to the correct diameter does not restore the case back to its original thickness. If this case is fired in a pistol with an unsupported chamber again, and this thinned section of brass happens to line up with the unsupported part of the chamber, there is a high probability that the case will rupture."

There is a difference between "bulge" and proper expansion. A "bulge" is when the brass starts to flow down the feed ramp. A properly expanded case, such as what you see 99.9% of the time, is not damaged and can be reloaded a bunch of times. The problem is people confuse normal Glock case expansion with a bulge.

This is a bulge:

 

[ny32182]

It might help if you post a close up picture of the crimp on a loaded round, and also a pic of one of the pulled bullets... there should not really be a ring in the bullet.

However, my money would be on "none of the above"... as mentioned, you generated a massive overpressure somehow. Not a little overpressure, but a big, massive one. I don't think a little bullet setback could make the case look like that. I'm guessing that somehow, some way, too much powder ended up in that one.

 

[Certaindeaf]

If a 9 gets set back 1/10" from minimum, the pressure is doubled. I think.
Neck tension is good.

 

[918v]

That all depends on the powder and the bullet and OAL. If that were always the case nobody would have any fingers left.

 

[Striker Fired]

I'd say it is a safe bet that the cause was loaded at/near max charge with a fast ,unforgiving powder & setback issues created way-overmax pressures in an unsuported chamber that shouldn't be loaded to max to begin with.

This is one of the main reasons I am not interested in any fast powders, I always use slower powders that fill the case up enough , and won't be as tempermental if the bullet gets pushed in a bit.

It's just one of those life learning lessons. Glad you or your other half didn't get hurt. Now ,time to save up for a replacement.

 

[Neutered10mm]

Well, just came up from the reloading area ... I pulled 2 of the remaining 35 suspect rounds, put their nose on the bench, put my thumb on the base and pressed pretty good (wish I had a way to measure as this was the point of the thread) ... the bullet recessed from 1.1315 to 1.084. Did another 1.132 down to 1.114 ... didn't bother checking further ... this batch will need to be broken down and redone. How much pressure was applied? I have no idea ... I'm 5'10", 210 lbs. with strong shoulders ... I've done plenty of automotive work with a torque wrench and my educated guess ... about 50 ft/lbs. of downward torque on the bullet.

I'd imagine it could be done to ANY bullet, but a properly tensioned/retained bullet would buckle/wrinkle the case first???

 

[Neutered10mm]

Oddly enough, I just sold a set of tires/rims to a guy the day before for ... drum roll ... $550