Calling Terry Murbach

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Rusty
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Calling Terry Murbach

#1 Post by Rusty » Sat Nov 02, 2013 5:56 pm

Years ago when I used to shoot .38's by the truckload there was talk of a detonation when using small charges of Bullseye. The claim at the time was that the small charges of around 3.0 grains weren't enough and the primer flash set off the whole charge at once.

Do you know if the was ever any concrete conclusions on these kabooms that happened in those cases. I'm still leaning towards double charges myself
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Re: Calling Terry Murbach

#2 Post by El Chivo » Sat Nov 02, 2013 6:15 pm

we talked about this recently and it was debunked as far as fast powders go.

The real culprit seems to be reduced charges of slow powders; the primer flashes along the airspace and only ignites enough powder to push the bullet partway down the barrel. Or perhaps the primer itself pushes the bullet out. Then the main charge goes off with the stuck bullet in the barrel.

I ran a google search and read all I could find. There was only ONE person claiming it happens with fast powders. All the others discussed the reduced charges of slow powders. Some addressed the fast powder claim, and pointed out the such a small amount of powder just doesn't have the power to blow up a gun. Bullseye burns up all at once anyway, so it ought to blow up with a standard charge if a half charge would do it. How could it burn faster than fast? The problem is with an obstruction, or a double charge.
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Re: Calling Terry Murbach

#3 Post by Rusty » Sat Nov 02, 2013 6:42 pm

A double charge is what I've always suspected, but you know how people are no one wants to admit they could or would do such a thing.
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Re: Calling Terry Murbach

#4 Post by AJMD429 » Sat Nov 02, 2013 6:52 pm

El Chivo wrote:The real culprit seems to be reduced charges of slow powders; the primer flashes along the airspace and only ignites enough powder to push the bullet partway down the barrel. Or perhaps the primer itself pushes the bullet out. Then the main charge goes off with the stuck bullet in the barrel.
Even that seems strange, though.
  • Normal Events: Say you have a cartridge-case full of powder that when ignited will expand to 1,000 times its volume in a couple milliseconds, during that time the bullet starts moving, and makes it a couple cartridge-lengths down the barrel. So 1,000 times the volume in three times the space, for 333 atmospheres of pressure. The bullet keeps moving due to its inertia having overcome the startup-friction, and the pressure.

    Abnormal Events: Now, say that bullet has been pushed five cartridge-lengths down the barrel by a partial-burn of powder, and somehow has managed to come to a dead-stop in that few millisecond interval, due to a significant pressure drop once the volume is six cartridge-worth's (but there was enough pressure when the volume was one cartridge-worth to start the bullet into the rifling). Now the rest of the powder ignites, in a six-fold volume of space; even if 99.9% of the powder is left to belatedly ignite, you have your 999-fold volume expansion in maybe six times the cartridge volume for 167 atmospheres of pressure. The bullet has already been swaged into the barrel and engraved by the rifling, and possibly has the outer layer warmed up by friction enough to be softer. Yet the pressure is enough to blow the gun up...???

    I realize my 'numbers' may be off, but the principle is what I'm trying to illustrate; if there is a 'delay' in full powder ignition, then the bullet will be even farther down the barrel than usual before peak-burn, so the peak pressure seems like it would be lower vs. higher, and I can't believe the bullet would be all that much harder to start moving, if indeed it really even would have a chance to actually 'stop'.
I don't see how that makes sense.

If I had a gun I didn't mind destroying if I were wrong about this, I'd push a bullet six inches down the barrel from the breech, prime a case and charge it with a normal load of powder, and chamber it in the gun while pointing 'up' to keep the powder in the case. Then I'd lower the gun to horizontal, and fire. I don't think this would blow up a gun. It would be the equivalent (sort of) of putting a 45 ACP powder charge behind a 250 grain bullet in a 45-70 case; powder goes off in a space five or six times the normal volume at ignition. Yes, bullet is in the barrel instead of just in the cartridge, but is there always more friction once in the barrel than when just shy of, or touching, the lands...?

Maybe this can be Sixgun's next experiment. . . :wink:

One thought would be that if one is talking only about REVOLVERS, then there is a much different series of frictions encountered by the bullet than in a rifle; first essentially none, then a steep increase when entering the forcing cone and the cylinder-gap may still be mostly occluded, then a decline as the bullet becomes swaged and engraved, and the cylinder-gap allows some venting.

QUESTION:

Are ALL the Kabooms from "reduced charges of slow powders" in REVOLVERS...???
Last edited by AJMD429 on Sun Nov 03, 2013 10:04 am, edited 1 time in total.
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Re: Calling Terry Murbach

#5 Post by Mescalero » Sat Nov 02, 2013 7:18 pm

Almost all the kabooms I know of came from Glocks.

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Re: Calling Terry Murbach

#6 Post by El Chivo » Sat Nov 02, 2013 10:31 pm

Yet the pressure is enough to blow the gun up...???
I agree, it doesn't sound plausible. The "chamber" is much larger with the bullet six inches down the tube. And what's keeping the bullet in that 55,000 cup of pressure won't budge it?

If a gun blows up with a reduced charge of slow powder, there's no other explanation, since you can't double charge those. A full case of that kind of powder would work fine. I said "if" because I'm skeptical that it happens. But there are those that swear it does.

The obstruction theory makes sense. 86er had a blowup because of a wasp in the bore. Could be a lot of guys out there that got mud in their rifle and didn't know it. Then there's also the two bullet loadings that happen with progressive presses. The inner bullet expands with the explosion and blocks the shoulder and neck, creating a plug and confining the charge to the chamber.

On the other hand, one type of Winchester powder warns not to load it down more than 3% or it may blow up.

25 or 30 grains of powder won't blow up a gun, and 2.5 or 3 grains of Bullseye will?
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Re: Calling Terry Murbach

#7 Post by Griff » Sat Nov 02, 2013 10:39 pm

I've had two "kabooms". Both in a .45 caliber, a 45ACP and 45Colt. The first and second were overcharges. Loading with low density presents challenges that even a careful reloader (I like to think I am...), needs to be cognizant of and take appropiate measures to protect against.

The one in my 1911, I truly don't know how it happened... and I only loaded personal protection type loads, so how an overcharge happened, I'm still clueless. Luckily, it simply bulged the barrel.

The second was during a cowboy match in Arizona. It was a definite overcharge, possibly a double. It also just bulged the cylinder on that chamber. But, like most cowboy shooters, I was using very light loads... Sent the gun back to Colt and they would've fixed it... but were going to charge me for new springs, bolt and trigger; all of which had been modified for competition. I ended up having a 2nd gen .357 cylinder recut for 45 Colt. But, those two instances made me all the more aware of the consequences for a minor mistake in reloading.
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Re: Calling Terry Murbach

#8 Post by earlmck » Sat Nov 02, 2013 11:49 pm

Griff wrote: Loading with low density presents challenges that even a careful reloader (I like to think I am...), needs to be cognizant of and take appropriate measures to protect against.
Amen to that, Griff!

A couple of times when inspecting charged cases I have found a double charge. One of those, the case before had just a dab of powder, so I think the powder measure managed to "bridge" without my noticing, and one was just a plain old earlmck booboo. I can no longer even force myself to seat bullets into cases where I haven't got an "eyeball" on the charge level. And I have developed a strong preference for charges that would overflow the case on a double charge.
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Re: Calling Terry Murbach

#9 Post by JimT » Sun Nov 03, 2013 12:27 am

This originally came from the target shooters in the 1960's and 70's .. standard load was a little over 2 gr. of Bullseye and a full wadcutter normally seated not quite flush with the case. There were blowups of S&W and Colt double-action 38's and people began to speculate on "powder detonation".

Hercules Powder Co. did extensive testing and produced a brochure they gave away for free, detailing their tests .. with photos.

They tried detonating the small charge of Bullesye, going to far as to rig as Colt Detective Special with a loaded 38 cartridge that had a detonator used to set off a stick of dynamite to fire it. They could not get enough pressure from the small charge of powder to harm the gun. They tried a lot of stuff and documented it all.

What they did find was seating the bullets deeper began to raise pressures dramatically. Using cast bullets often excess lube builds up on the end of the seating stem and the bullet gets shoved deeper and deeper into the cartridge case. A combination of an accidental double charge and seating the bullet - I forget but I think it was .125" - don't quote me on that ... it was not a large amount .. raised pressures to over 70,000 psi .. enough to destroy a 38 revolver.

In the earlier days of Cowboy Action Shooting I read of some who blew up 3 44-40 revolvers in about a year. Using a 180 bullet and light charges of fast powder. "DETONATION" was the cry! Eventually the handloader discovered that loading on the progressive loader, lube would build up on the seating stem and would hold the bullet from going into the cartridge. It remained up inside the die .. OUT OF SIGHT. Looking at the cartridge he thought he forgot the bullet, seated a bullet in the case mouth and went on. EXCEPT NOW THERE WERE TWO BULLETS IN THE CARTRIDGE AND NO AIR SPACE AT ALL FOR THE POWDER. He weighed all his cartridges and found more than a couple if I remember correctly. He sectioned some to show people what can happen.

We do hate to admit we screwed up. It's much easier to blame "detonations" ... alignment of the planets .. or our mother-in-law. :)

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Re: Calling Terry Murbach

#10 Post by Sixgun » Sun Nov 03, 2013 8:25 am

+1 on Jim T's assessment. I wish he would come back on a regular basis as he always had great answers to about everything gun oriented.

Even that 1886 that I blew up. Looking back, I was told metal fatigue, but I still think it was me, being in a hurry or the phone ringing.

Just to prove a point, I'm going to take Doc's advice. I am going to load five 45-70 cartridges with varying charges of Bullseye and a 500 gr. bullet. I'll start with 1 gr., and increase it 10 grains at a time until I reach 41 gr. and see what happens. I need a volunteer from the board to hold my beer while I pull the trigger. ------6
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Re: Calling Terry Murbach

#11 Post by Rusty » Sun Nov 03, 2013 8:59 am

Thanks Jim, I hadn't heard that explanation at all. The CAS shooters I see today is kind of what got me to thinking about this.
We used to shoot the 148 gr hollow based wadcutters over a small charge of Bullseye. I can't remember the exact charge, I think it was around 3 grains. Some liked a little more recoil so they would go higher. Others thought they were really saving a pile of cash by cutting back to 2.8 grains. I used to say BIG DEAL! Powder wasn't all that expensive. When I shot the department reloads I shot what they gave us. When I loaded my own I loaded with either HP38 or 2400. Mainly because I started with those and they worked.
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Re: Calling Terry Murbach

#12 Post by earlmck » Sun Nov 03, 2013 10:15 am

Sixgun wrote:Just to prove a point, I'm going to take Doc's advice. I am going to load five 45-70 cartridges with varying charges of Bullseye and a 500 gr. bullet. I'll start with 1 gr., and increase it 10 grains at a time until I reach 41 gr. and see what happens. I need a volunteer from the board to hold my beer while I pull the trigger.
OK 6, I'll hold your beer if you want to bip on out to Oregon for this test. But after shooting that 1-grain load, make sure you drive the bullet on through the barrel with a rod before you shoot the 11- grain charge or you might end up with a bulged barrel or something. (Yeah, I'm sure the 1-grain charge will leave the bullet in the barrel, not even half-way up).
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Re: Calling Terry Murbach

#13 Post by Griff » Sun Nov 03, 2013 10:39 am

Thanks Jim. I'd forgotten about those double bullet incidents. Had it happen to me once, and rather recently. But, I'm no longer loading such light loads in my 45 Colt, and when I noticed that one didn't seat quite fully... I pulled it apart, viola! A bullet under it! At the time I had about a hundred loaded rounds in the basket... so I went on a weighing marathon. Luckily, it was the only one.

As they used to say on Hill Street Blues, "...let's be careful out there!"
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Re: Calling Terry Murbach

#14 Post by JimT » Sun Nov 03, 2013 3:00 pm

Sixgun wrote:+1 on Jim T's assessment. I wish he would come back on a regular basis as he always had great answers to about everything gun oriented.

----6
I appreciate the compliment Sixgun ... I read the posts here as often as I can .. don't write much. I am at the age where I have experienced a lot of things that people wonder about. BUT I am also at the age where I sometimes forget what I have experienced!! :D

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Re: Calling Terry Murbach

#15 Post by Sixgun » Sun Nov 03, 2013 3:16 pm

Thanks Jim.......I have come to realize that, whether it's gun issues or life issues.----6
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Re: Calling Terry Murbach

#16 Post by wecsoger » Sun Nov 03, 2013 4:47 pm

I anxiously await the results of the .47-70 test, that's going to be interesting. And I would offer to stand by and hold your beer, but you're aways from southwest Ohio, so we'll wait for another time.

The detonation theory with Bullseye never made sense to me. And I'm not so sure about the double charges.

If you're running light loads with wadcutters, that's going to be in the 2.0 and 3.5 gr. range. Double charge that and you're going to be at 4.0 to 7.0 gr.

Now 7.0 gr. or anything north of that I'd only be shooting in a Ruger GP100, but I can, I have and you can shoot them all day.

Now a triple charge, which will be 6.0 to 10.5, at the high end of that it will be attention-getting. Buy you gotta work hard at screwing up enough for a triple charge.

I'm liking the double bullet theory.

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Re: Calling Terry Murbach

#17 Post by Malamute » Mon Nov 04, 2013 11:23 am

I've been interested in the detonation idea myself. Detonations of slow rifle powders in large cases does seem possible, not so sure about very light charges of pistol powders. The thing that makes me think its possible with rifle powders is related to shaped charges. In a very remote few instances, perhaps its possible that the pressure wave coincides to cause a spike. A shaped charge doesnt have a huge amount of charge, its just shaped so its pressure wave is focussed on a very small point and allows it to do what even a much larger charge would not. An RPG is an example. Without its cone shaped charge it wouldnt penetrate armor, with it, it does. Its just a focussed pressure wave coinciding on the intended point. Not saying its a definative argument, just that in light of the way pressure waves can be focussed, it may be possible.

I like building light loads in rifles, I just follow the common advice to avoid slow buring rifle powders to do it after the reported (if rare) detonations. Many reported doing it for years without issue, but some did experience it, for whatever reason.
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Re: Calling Terry Murbach

#18 Post by Canuck Bob » Mon Nov 04, 2013 3:19 pm

Years ago I double charged a Colt 45 ACP, series 70 mk1. The gun and I survived. I gave that powder away and decided to never load reduced charges that did not overflow a case if double charged. This is my rule and I sure realize many qualified loaders use small charges all the time safely. I simply do not want a repeat performance. Escalating powder costs had me reconsider but I decided not to change and researched adequate powder that meet my needs. It also helps that my loading does not involve pistols and large capacity rifle cases. Just another reason levers are the perfect rifle and Lee Enfields are the funnest old battle rifle.

This is one of the most baffling issue along with using fillers. There seem to be a lot of well known folks who say it is not an issue and others who warn about blowing up one's gun or ringing the chamber. For a guy like me it almost seems it is best to just avoid the issues. I do plan to experiment with filler for cast shooting some day. Also a good reason to shoot lever cartridges with their narrow tapered cases and mild neck constriction.

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Re: Calling Terry Murbach

#19 Post by getitdone1 » Mon Nov 18, 2013 9:04 pm

earlmck wrote:
Griff wrote: Loading with low density presents challenges that even a careful reloader (I like to think I am...), needs to be cognizant of and take appropriate measures to protect against.
Amen to that, Griff!

A couple of times when inspecting charged cases I have found a double charge. One of those, the case before had just a dab of powder, so I think the powder measure managed to "bridge" without my noticing, and one was just a plain old earlmck booboo. I can no longer even force myself to seat bullets into cases where I haven't got an "eyeball" on the charge level. And I have developed a strong preference for charges that would overflow the case on a double charge.
earlmck,

Yes indeed. Always "eyeball" each charged cased before seating the bullets. And.....when doing so remind yourself to look at each individual case. And, you are also super correct when you say you have a preference for powders that will overflow the case with a double charge.

I've told this before, but one time I failed to put powder in a 44 mag case. Pop and bullet stuck in the barrel. If I had been shooting that model 29 S&W fast bad things would have happened.

Don

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