Blank Barrel Revisited - Sectioned To See Damage

[reconbob]

A while back wwiifirearms posted this photo of a barrel he had been

using to fire blanks:

 

http://i51.photobucket.com/albums/f392/reconbob/blank.jpg

 

 

I was interested in taking a closer look and offered to cut the barrel

open so we could all see. Wwiifirearms was kind enough to send me the

barrel...so here we go. Notice that the ring is a very

rough gouged surface - looks like it was done with a chisel! No smoothness,

no appearance of "flowing" or burning/erosion, rather the appearance

of being hammered!

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1596.jpg

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1598.jpg

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1597.jpg

 

Bob

[giantpanda4]

Bob,

That is very interesting!

Can you show a pic with a fired blank cartridge in it? I am curious as to where the ring is - i suspect right After the end of the brass, but it could be before that, actually formed behind the brass at the end of the cartridge.

Thanks to both of you guys for doing this!

[Hawkeye_Joe]

I wonder how many re-enactor M1 Garand barrels look like that??

[RoscoeTurner]

I wonder how many re-enactor M1 Garand barrels look like that??

 

 

Or MP44s or MP40s.

[wwiifirearms]

Thanks for doing this for us! I really wanted to see what was going on and hoped it would save other barrels from the same fate.

-wwiifirearms

[fortyfivecal]

thanks for sharing the information and photos Bob, do you have a blank cartridge that has been fired to demonstrate the relationship between the cavity in the barrel and the spent blank? Edited November 24, 2010 by fortyfivecal

[reconbob]

Sorry - here is a fired blank in the chamber. Its a Swanson

blank, but I don't know what kind of blanks the previous owner

of the barrel used. From what I hear Swanson blanks are as

hot as it gets...

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1602.jpg

 

Bob

[dalbert]

Very cool post, Bob! I'll add this to the reference post listing ASAP...

 

David Albert

dalbert@sturmgewehr.com

[scoutcompany]

judging from the photo it looks like the brass was cutting into the bore. or do you people think it was the actual explosion that did that?

 

 

[fortyfivecal]

judging from the photo it looks like the brass was cutting into the bore. or do you people think it was the actual explosion that did that?

 

while not a shaped charge expert, i wonder if as the nose of the blank opens, there is a focused energy release that scours the barrel until the charge pressure dissipates and travels down the barrel..

[reconbob]

I don't know for sure. If this gouging was the result of the powder gas,

I would have expected the ring to be smooth from the erosion of the gases.

Its hard to tell in the photos but the recessed area behind the ring is pitted,

not smooth - so maybe the gases displace and over time burn the steel,

making it very brittle, and it flakes or burns off?

I also wonder how much of this could be the hammering of the brass, since

brass is softer than steel? It would help if we knew what kind of blanks the

reenactor was using - they could be longer or shorter than the one in the

photo.

There are a lot of Thompsons out there shooting blanks, I wonder if more

examples of this will surface...

 

Bob

[wwiifirearms]

Sorry - here is a fired blank in the chamber. Its a Swanson

blank, but I don't know what kind of blanks the previous owner

of the barrel used. From what I hear Swanson blanks are as

hot as it gets...

 

http://i51.photobucket.com/albums/f392/reconbob/IMG_1602.jpg

 

Bob

It was Swanson blanks that did the damage. If you still have the Blank Firing Adapter, it might also be interesting to note the size of the hole, not sure if an incorrect BFA contributed to the damage.

 

I noticed your fired Swanson blank is still intact in the crimped area. The blank brass that came out of this barrel was always split like the peddles of a flower after firing.

-wwiifirearms

Edited November 25, 2010 by wwiifirearms

[fortyfivecal]

I don't know for sure. If this gouging was the result of the powder gas,

I would have expected the ring to be smooth from the erosion of the gases.

Its hard to tell in the photos but the recessed area behind the ring is pitted,

not smooth - so maybe the gases displace and over time burn the steel,

making it very brittle, and it flakes or burns off?

I also wonder how much of this could be the hammering of the brass, since

brass is softer than steel? It would help if we knew what kind of blanks the

reenactor was using - they could be longer or shorter than the one in the

photo.

There are a lot of Thompsons out there shooting blanks, I wonder if more

examples of this will surface...

 

Bob

 

again, thanks for your time taken Bob, this has been very enlightening.

[jim c 351]

Attn: reconbob,

The guy that I bought my M1 Savage from was one of those blankshooting re-enactors.

I'm pretty sure that the blanks he used were the ones you pictured.

The barrel that came with the gun had the bulge that you pictured plus 3 more near the muzzle.

I would be more than happy to donate the barrel to you to cut open and post for the good of all . Let me know if you are interested.

I really wish that these re-enactors would use toy guns and just shout -bang-bang -bang, like I did when I was 12 years old instead of ruining a C&R.

Jim C

[RoscoeTurner]

I really wish that these re-enactors would use toy guns and just shout -bang-bang -bang, like I did when I was 12 years old instead of ruining a C&R.

 

 

Unfortunately too many reenactors look at C&Rs as toys.

[fortyfivecal]

there are alternatives, deerslayers blankfiring set-up for example, even more practical in that a re-enactor can buy a new thompson "carbine" and have a correctly dimensioned and contoured 10.5 inch barrel installed for blankfiring, and avoid the SBR tax stamp legally.

 

it is a shame to see an original barrel with a good bore used for blankfiring, especially after seeing Bobs photos of the halved blankfired barrel.

Edited November 26, 2010 by fortyfivecal

[Z3BigDaddy]

I really wish that these re-enactors would use toy guns and just shout -bang-bang -bang, like I did when I was 12 years old instead of ruining a C&R.

 

 

Unfortunately too many reenactors look at C&Rs as toys.

 

 

The problem with that is?

[RoscoeTurner]

I really wish that these re-enactors would use toy guns and just shout -bang-bang -bang, like I did when I was 12 years old instead of ruining a C&R.

 

 

Unfortunately too many reenactors look at C&Rs as toys.

 

 

The problem with that is?

 

 

They end up screwing up too many then wonder why.

 

[dalbert]

I noticed your fired Swanson blank is still intact in the crimped area. The blank brass that came out of this barrel was always split like the peddles of a flower after firing.

-wwiifirearms

 

Based on the description of the split casings noted by wwiifirearms above, I wonder whether the (too small) size of the hole in the BFD may drive the deformation of the brass, and the erosion of the barrel. If the gas has nowhere to go for too long, could it blow out the brass, and cause this erosion over time?

 

David Albert

dalbert@sturmgewehr.com

[2ndArmored]

I really wish that these re-enactors would use toy guns and just shout -bang-bang -bang, like I did when I was 12 years old instead of ruining a C&R.

 

 

Unfortunately too many reenactors look at C&Rs as toys.

 

 

The problem with that is?

 

 

They end up screwing up too many then wonder why.

 

Is the barrel the only part that gets wrecked?

[Z3BigDaddy]

I really wish that these re-enactors would use toy guns and just shout -bang-bang -bang, like I did when I was 12 years old instead of ruining a C&R.

 

 

Unfortunately too many reenactors look at C&Rs as toys.

 

 

The problem with that is?

 

 

They end up screwing up too many then wonder why.

 

I would much rather see a few ruined barrels than have them turned into safe queens...

[reconbob]

Jim - if you send the barrel, I will cut it and photograph and post. I have the blank

adaptor for the barrel pictured so I will check the diameter of the orfice and report

back. I will also cut the front of the barrel so we can see whats going on right behind

the adaptor.

If the blank adaptor is too small, the powder gases could easily be pressurizing

the entire bore and filling up and flattening the walls of the case against the chamber

walls. I have experienced this before. I have done a lot of work with blanks and

blank firing guns and barrels lately. For a Kahr semi-auto and a special blank fire

only barrel we make (so you can't compare exactly to a standard .45 barrel) the

orfice that works the best with Swanson blanks (going by memory since I am traveling)

is 0.246". And again, this is for a Kahr with the 29 pound to cock recoil springs.

If I recall correctly the orfice for the barrel in the photos is much smaller, plus the

adaptor is deeply seated in the bore (over an inch) plus its a full auto without the monster

recoil springs. So add this all up and I think the gun was really being pounded by

the blanks and adaptor.

Stay tuned...

 

Bob

[RoscoeTurner]

I would much rather see a few ruined barrels than have them turned into safe queens...

 

 

I don't mind seeing them shot with live rounds but I have seen too many full autos and semi autos screwed up by reenactors tapping the barrels, firing blanks that are too hot for the setup they have and damaging the firearm because they wanted the noise to be louder. Operating the firearms as they were designed to be operated rarely damages them but as in the case of this thread you see what firing blanks in a Thompson barrel can do.

 

One more recent episode I saw was a clod who blank adapted a very nice all matching zero series P38 and on the first blank being fired he destroyed the pistol. He was clueless to how back pressure from a blank can reach a point of being too much and how tapping threads in a collectable firearm ruins its collector value. He was lucky he was not hurt when the pistol blew up.

 

Given the choice between a ruined / destroyed firearm and a safe queen I will vote for the safe queen every time.

[giantpanda4]

Bob - thanks again for posting this!

 

I am of the school of thought that there is some kind of shaped charge thing going on. It looks like the erosion ring is after the end of the cases. Someone said their cases really feather out and are torn - that tells of pressures, but this ring is from gasses not flowing straight down the barrel but being redirected towards the edge of the case.

 

Anyone have any experience shooting blanks other than crimped ones? Like the WWII shot cartridges where the end of the case has a paper wad of some sort. I know these will cause havoc with feeding into the gun. Bit if we find someone who uses this type of case regularly and take a look down their barel - we may get a clue (ring or no ring!).

 

just my $.02...

[fortyfivecal]

its too bad some one doesn't have access to a test chamber like the automotive institute(s) have for examining what go's on in a combustion chamber. they use high speed camera's to document the detonation. that would tell the tale regards this topic.