In my research- I've found that there's alot of comments, replys, and concerns up & down here-
about the dangers, effects, and concerns of (BP residue) corrosion getting into the weld joints of the cannons & mortars we build.
I offer up my ideas on this subject:
A little background:
1. I grew up in USMC Avaition. Parris Island graduated- Class of Sept. 1973.
2. Working on the Jet Fighters & the Helicopters of a Sea going Force-
and, after serving almost 8 years- the last four years of it as a Shop Head/NCOIC on the Marine One crew-
I think I've been to every Corrosion Control Class in the known Universe.
3. I didn't own a car for 3-4 years. I drove motorcyles instead-- for about 100,000 miles total.
4. I ate 'my own cook-n', and didn't get married (the first time) until I was 26.
5. Driving motorcycles that much, going to all those Corrosion Control Schools, and maintaining my own cast Iron frying pan-
I learned alot.
One of the things was that using the real expensive, spray cans of, "Motorcycle Chain lube"
was better than any other oil-- especially running 'cross country between Dallas, and Quantico, VA--at free way speeds.
This is REAL!! sticky, slimey, lubricating stuff.
It sticks to things like 'poop' does on a baby blanket-- and is harder to completely get off your fingers than a bugger.
After 50-60 miles, common engine or spray can oil has all flown off a properly adjusted, Yamaha 650, motorcycle chain.
Using the 'good stuff',,,,,, after 120 or so miles- the same chain is still 'wet' with it.
Another thing I learned was that the more ya cooked on a Iron fryiny pan,
the more the cooking oil sealed the pores in the Iron it was made from,
and the more it resisted rusting after it was washed and not used.
My question/idea is:
On these BB Mortars-
Since it isn't practical to fill the gap between the Breech Plug and the barrel due to corrosion concerns----
What do ya guys think of the idea of sealing the welds with oil/motorcycle chain lube?
I think it would work like sealing a old style cast Iron frying pan.
Spray the heck out of it between every few shots with that thick, oily, snot looking goop........
The chamber pressure from firing the BP would drive oil down into the weld pores instead of the highly corrosive BP gases.
Washing it between and after firing,,, you'd get all the top crud off.
Next time, spray it again: Just like like cooking with a Iron frying pan.
Oil it, use it, clean it, spray it again the next time,,and so on,,,,,
In the long run--
No self respecting rust germ would ever even think about living in a weld joint under such conditions.