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Old March 19, 2001, 04:38 PM   #1
Mikul
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This is a followup to my topic of tumbling bullets that has spurred it's own topic.

I was at the range testing IMI jacketed bullets vs. Berry's. Everything was great until I got 150 rounds into it.

I loaded a fresh magazine into the gun and realized that the slide was still forward. I worked the slide and a shell casing came out.

?????

I took the gun apart and looked down the barrel.

DAMN! This is not my day.

A round was lodged in the barrel. The brass was covered in carbon and the primer is shaped around the firing pin (although I'm not certain this brass was the one I manually ejected, but it's the only one that looks bad). The barrel appears fine on the outside. The grooves on the polygonal rifling appear to be stripped down to bare metal. The grooves are bright silver, but the rest is black. Does anyone know what that indicates?

It looks like I had a round lodged in the barrel and fired another one after it. I can't explain the pressure signs on the brass any other way. A double charge would do that, but I sure shouldn't have a bullet stuck in the barrel.

I didn't feel a thing while shooting. I would have felt a squib load. Any time something feels unusual, I strip the gun.

I can't figure how I got a squib load from my 550b.

Is it possible that I had a double charge which fouled the barrel so badly that the next round got stuck? Could this be a case of excessive crimp? Or could it be (cringe) that I fired a bullet into a previously stuck round?

I hope I'm not going to need to replace the barrel.
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Old March 19, 2001, 05:55 PM   #2
Patrick Graham
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I have had "many-o-those" days.

I've got at least 20 squibs hiding in a pile of 300 45 acp loads that I've been meaning to pull for a long time.

If you leave some kinds of powder sitting in the powder measure for a long time it will start to "clump". The measure will dispense a few then go dry because it has a "clump" in it's throat. Sometimes the clump will break up a little allowing the powder measure to toss a few more loads before it goes dry again.

I now take the entire 550 tool head and shake it up if I haven't used it in a few days. Then I re-measure the charge before I start. Sometimes you can see the clump when you shake up the powder measure.

You didn't hurt the barrel, just get a brass rod and start driving the bullet back towards the chamber.

If you would have followed up with a live one you would have known it, if you were shooting 45. I did that once too. 1911's do go "KA-BOOM" when that happens, unless the follow up round was a squib also.. that would be interesting.
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Old March 19, 2001, 07:01 PM   #3
Mikul
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After cleaning that barrel, it's clear that there's no permanent damage done (Whew!).

Due to the pressure signs on the primer, a squib doesn't seem likely. I almost wish that it were the problem.

I'm thinking that excessive crimp is what is wrong. I've had the same setting on the die for 9 months without a problem. Perhaps it has been tightening. When I pulled 125 of the plated rounds that were giving me trouble I noticed that half of them were dented below the crimp line while the others weren't. Someone had suggested that the plated round problem (tumbling in the air) was the result of a crimping problem.

I've already got 175 plated rounds left to pull. I'd hate to have to add the 500 jacketed rounds to the list.
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Old March 19, 2001, 07:08 PM   #4
Mal H
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Mikul - Like Patrick, I don't think you fired into an already plugged barrel, so probably no harm done. The symptoms sound like a round with little or no powder. The blackened case shows that it didn't seal in the chamber and the backed-out primer says that the pressure didn't get very high. (Primers will normally be pushed out of the seat and then get pushed back in when the pressure drops and the casing pushes back on the breech. The degree to which this occurs depends on head spacing, but it almost always occurs even though it isn't obvious.)

Check the case in question with a caliper against one that you know was fired in your gun. I'll wager it hasn't been expanded much above the web to the mouth compared to the fired one.
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Old March 19, 2001, 09:19 PM   #5
Mikul
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Left: Normally fired brass Right: Brass from lodged bullet

Mal, that is an excellent suggestion.

I measured the messed up brass, two rounds that fired normally and one that I just pulled. I measured at the neck and in the middle.

FUBAR Brass
neck: 0.378"
mid: 0.374"

Normal Brass #1
neck: 0.382"
mid: 0.389"

Normal Brass #2
neck: 0.381"
mid: 0.390"

Pulled Brass
neck: 0.378"
mid: 0.376"

Of more interest than the size comparison (fired rounds were 0.004" wider at neck and 0.016" wider at the middle) was the fact that both fired rounds are wider in the middle than at the neck while the unfired (pulled) brass was narrower, just like my problem load.

I have never heard about primers deforming when they fire and then getting pushed back when the round fires. My manual simply shows a deformed primer like mine to be a sign of overpressure.

Perhaps I don't need to pull the 500 jacketed rounds, but I'm certainly going to weigh them all.

BTW, what didn't seal in the chamber? The brass?
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Old March 19, 2001, 10:50 PM   #6
Mal H
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Mikul - good pictures, and very informative. The FUBAR primer has the classic look of a primer that has had little or no pressure on it to flatten it like the one on the left. Now I'm positive that you either had no powder or it was a squib load. If it was a squib, however, you would usually find the chamber filled with unburned powder.

An overpressure primer will usually completely fill the primer pocket, but not always. Primers are not the best way to determine overpressure. Accurate measurement of the web is the best way. The web should not expand more than around .0005" to .0015" at most. If a web expands more than that, overpressure is likely.

Yes, the brass will usually expand and seal the chamber while the pressure is highest. Then it relaxes a little and can be withdrawn. This is the primary reason why oiling the chamber is never recommended (or at least the oil should be wiped out before shooting if it was oiled to prevent rust). If the brass expands and then slams against the breech because it can't create enough friction, then premature wear or even breakage of the breech face and firing pin can occur after repeated pounding.

Weighing the remainder of your rounds is an excellent idea. The components will usually average out to be close enough in weight to determine if the powder is missing.
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Old March 19, 2001, 11:00 PM   #7
labgrade
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Good diagnosis methinks.

A revolver will seldom allow a full cylinder rotation popping only primers - they will back out & lock up the cylinder at about #3 or 4.

As stated, the reason the case was black was due to zip for pressure to expand the case & seal the chamber.

Also, I have read that keeping powder in the plastic hopper for extended periods is a bad thing. Something to do with the hopper's plasticizer characteristics can work it's own magic on the powder composition reducing its effectiveness.
No personal experience as I empty it after each session.
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Old March 19, 2001, 11:46 PM   #8
Scooter2
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That primer definitely looks like a squib load. Try firing a primed case (no bullet or powder). You should get the same results.
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Old March 20, 2001, 05:28 AM   #9
Patrick Graham
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Yep
That's a squib.

I'd pull those puppies.
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Old March 20, 2001, 09:42 AM   #10
Mikul
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That's for the very informative information. I didn't want to have to learn this, but at least I learned something from the experience. Measuring the diameter of the brass was a great idea.

The powder doesn't live in the hopper more than a week and I only leave enough in there to be below the plastic.

I weighed the remainder of the rounds and pulled 6 which appeared okay. It's amazing the difference between rounds with the same bullet, charge, primer, and brass manufacturer. And Speer's brass is 4.2gr lighter than S&B's which is nearly the same as the powder charge that I was using. I weighed them by comparing them to other with the same brass manufacture. Anything within 0.2gr one way or the other was kept.

Off to the range again today. Hopefully the third time is a charm.
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