Gillmor Ordnance - Bronze Foundry Pieces

[Victor3]

Do it again.

Why? All the data is still there in the old thread.

[gunsonwheels]

COME ON 1SWAMPTHING... PLEASE POST YOUR NDT RESULTS. 

From my very limited observations very few bronze pieces are given a thorough NDT survey and consequently, very much of the rheotric regarding bronze and liner requirements is just that... rhetoric... unsupported by any hard data of NDT survey results versus liners versus failures with and/or without liners...??  For me, I will make it out of steel and paint it bronze. 

[1swampthing]

First I must apoligise to gunsonwheels for not promptly posting but I am a two finger typer and have been working 12 hr shifts. When I first got my barrel the first thing I did before firing a blank load was an inspection of the inside of the barrel to see if boring had exposed any pits or voids. I found one spot where there were three small pits with the largest being the approximate dia of a number 4 birdshot and the other two about the dia of a number six birdshot and the last the dia of about a number 7 1/2. These were in an area you could have covered with a nickle. I felt confident of firing blank loads and did so with loads up to 12oz fff. After approx a dozen blanks were fired in it I finally got it to the lab to be checked prior to considering any live fire. To quote from the report "Two radiographs were taken of the Howitzer end showing the igniter port and transfer to the rear head of the howitzer(he was trying to say the powder chamber and the necked down area where the barrel reduces down to the 3.3" chamber itself) Several small inclusions or voids were found. These voids were of a minor nature and did not propagate into the material. No linear indications were found in the radiographs. Additionally an ultrasonic compressional inspection was also performed on the barrel of the Howitzer using a 1"-1mhz transducer. Due to the cast nature of of the piece a full scan was not possible. The transducer had to be picked up and placed in each location to get a good back reflection signal. No items of a detrimental nature were observed during this inspection. No linear indications were found during either inspection." From what I could gather the small voids or inclusion found were similar to the small area I found in the bore with the pits the dia of birdshot. The ndt tech told me that in his opinion the voids he found were of such a minor nature as to have virtually no effect on the integrity of the barrel. I will in the future be using my gun primarily with blanks for reenacting and cerimonial purposes but if the time comes when I should choose to live fire it I have confidence that with the proper charge of cannon grade powder I will have no problem. Last weekend I went to a monument dedication and as the monument was unveiled I fired a blank with 14ozfff with about two cups of fine sifted sawdust ahead of it and all I can say is my baby sure has a sweet voice.

[gunsonwheels]

I want to thank personally 1swampthing for going to the expense and time to get his tube surveyed and for posting his NDT report for all of us interested. 

I would feel safer firing next to this gun than next to one that had a liner but was suspected of being akin to Colonial Williamsburg's efforts at casting bronze... but had been all nicely smoothed over with parent metal and a tungsten inert gas torch.  But without an NDT report, a linered piece of garbage would be better than "just, or only, the garbage".  ...so I suppose the rationale for the rule(s).

[GGaskill]

Well, I haven't found the Strength of Materials text yet but I did talk with my Professor Emeritus (Mechanical Engineering) friend and discussed the subject with him.  It was his opinion that the liner would expand plastically (take a permanent set) until it was a tight fit inside the outer shell and then the shell would start taking up that part of the load that was beyond the strength of the liner.  But we did no calculations.

So I will keep looking for the Materials text.

[flagman1776]

www.youtube.com

[de_lok]

I too believe that is the answer...

They know what I am finding out... bronze guns, especially repros,  can be pretty crappy internally (like I said, if I get a porous and bubbly mess of a barrel casting, I can go over it with the TIG torch and make it look great... on the OUTSIDE... but it is (or can be) a bomb casing underneath).  So if I am a sponsoring organization and have to go find liability insurance to cover my events... darn right I am going to require liners.  The only other option would be for the sponsor to hire an NDT (Non-Destructive Testing) contractor to be at the meet,  out in the "south 40" with a lead encased Cobalt 60 pill, lots of film and a developing shack to assure me those UNLINED bronze pieces are safe and will not kill someone... especially if it might be me!

On the other hand, if I have machined my tube from solid bar stock and TIG'd on the trunnions, I would be inclined to stay home from shoots requiring me, with my high-integrity tube, to have a liner.  I'd go find some other rednecks to shoot against (and possibly let one of THEM kill me).  Maybe you can't win but by building garbage and lining it!!!!!!

Now, that's what I'm talkin' about ! ! 
It is true however, that for the few that take the time, trouble, and expense of making/owning well engineered (safe) artillary pieces, there are always those that show up with "junk". With product liability and civil lawsuits a constant threat to manufacturers and event organizers, it's a wonder we are still able to enjoy this hobby.....................................................................................Like GOW said, have to find some redneck buddies to shoot with...........lol