Reactivating Moffatt 3.4-inch rifled howitzer

[cannonmn]

We  began work today, the strap dropped open after only 30 or so light sledgehammer blows.  We heated and hammered on the breech door for a couple of hours with no significant movement-then left it to try again tomorrow.

When we pulled our zinc anvil out of the chamber area, an old piece of tin cartridge was stuck to it.  In the slideshow, this is the little black fragment next to the tape measure.

http://s17.photobucket.com/albums/b62/cannonmn/miscforumsetc/forums44/?action=view&current=d136ed83.pbw

[KABAR2]

Were the sides of the locking surfaces painted? it looks like it by the color, that probably kept the amount of rust down
making it easier to move the strap. Glad to see your progression, Do you have a navy carriage they will fit?

[cannonmn]

Do you have a navy carriage they will fit?

yes.  On the other question, there was no paint on the mating parts, it just had very little rust.

[cannonmn]

Completion of disassembly:  Today just about as soon as we began hammering with the 100-lb. rod-hammer, the breech began to open.  The penetrant had worked into the rust overnight and dissolved it, just as happened with the other gun.  We did not get to try any other penetrants because we had begun using PB Blaster on this one some weeks ago, before we were aware of the others we'd like to try.  The extractor on this gun is broken, but it is a simple spring steel part which I can have a friend reproduce at minimal cost.  I notice the breech cone contour is different on this one, there are raised rings at top and base of the cone. 

Before I can mount either gun, I will have to get a new elevating screw made, because that part is considerably shorter than the standard screw used on the heavy Dahlgren boat howitzer.  I will also need to make the steel operating lever which raises the barrel for loading.  As previously discussed, I will also need to make some cartridge cases.  I think sheet steel or aluminum will be close to original design, which as far as I can determine, was made of tin.

http://s17.photobucket.com/albums/b62/cannonmn/miscforumsetc/forums44/?action=view&current=f1871ae9.pbw

[KABAR2]

With everything going on I missed the completion on getting the breech open in those first photos it looks like
the breech had a massive amount of scale rust /corrosion and that the breech actually looked deeply pitted,
I was happy to see when you used the pneumatic chipper that it wasn't as bad as it appeared.
I look forward to the day when you are able to mount these and return them to service.

Allen <><

[cannonmn]

Thanks Allen.  Workin' on them slowly maybe one day a week now, got other stuff to do.  It took a full day to get the tiny extractor screw out.  The base part of a Navy 3-inch 70 cal. cartridge case is just about right for the 12-pounder smoothbore, so we're figuring out how much of it we can keep and still get it fully seated so the breech will close.  It'll have to be pretty stubby to work, maybe a couple of inches max; we'll need to turn down the outside also.  We already turned down the rim. 

[artillerybuff]

WOW!  That cleaned up beautifully.  Very nice work~   Anthony

[Cannoneer]

The base part of a Navy 3-inch 70 cal. cartridge case is just about right for the 12-pounder smoothbore,..........

Your description of this naval shell threw me, until I looked it up.

3"/70 Mark 26 Gun

[cannonmn]

Thanks Boom.  The linked site has some critical errors and seems to confuse the older 3"/50 system with the later much more ambitious 3"/70.  I recommend this site, which was referenced by the other, but something seems to have gotten lost in translation by whomever put the wiki article together. 

http://www.navweaps.com/Weapons/WNUS_3-70_mk37.htm

[Rickk]

Reverse electrolysis will remove all that rust with minimal effort on your part, and leave all the good metal behind.

It's a fairly simple process. I use it to restore old kerosene lanterns. The rust comes off, but any remaining tin plating is left behind unharmed.

All you need is a battery charger, a tank big enough to submerge the barrel in, and some wire, scrap steel, and washing soda. You could probably remove all that rust in a week or two with no more than a daily wire brushing of loose rust and the anode (scrap steel)


 If you are interested in details, let me know.

[cannonmn]

Thanks, we got all the rust off.  These approx. 1000 lb. cannons didn't seem like really good candidates for electrolysis or I would have done it.  Victor likes electrolysis too, he posted how he cleaned up inside of a rifled barrel using that, very ingenious.

[RocklockI]

cannonmn , doesnt this cannon seem similar to the small bronze one you've posted about ?

it's an intersting ...type of lock-up .   

[cannonmn]

cannonmn , doesnt this cannon seem similar to the small bronze one you've posted about ?

Some of us lump this general type of early breechloader under the term "strap guns."  There have been quite a few variations on the theme posted here during the past two years.