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I am surprised to learn from the Professors post that T7 is little different from Pyrodex as I have never experienced the visible corrosion that was so common with pyrodex.
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I was under the miss impression the t7 was a nitro cellulose powder ....T7 does perform more like smokless than black (sharper report and very little fouling).
Thanks
Colt
Greetings My Good Colt
Black powder is a mechanical mix of potassium nitrate, sulfur, and charcoal only.
Pyrodex is classified as a sodium benzoate substitute for black powder
Here is the original patent formulation of Pyrodex which has been modified slightly but still the primary ingredients are the same:
45 parts of potassium nitrate
9 parts of charcoal
6 parts of sulfur
19 parts of potassium perchlorate
11 parts of sodium benzoate
6 parts of dicyanamide
1 to 4 parts of water
T7 is a "beefed up" version of Pyro.
They are both BP substitutes, one additive slows them down a little so they pass the regulatory agencies as a non-explosive.
I suspect that is the sodium benzoate
the perchlorates boost performance, but can cause a different sort of corrosion.
both seem to have now omitted the dicyanamide compounds, which may (or may not) have contributed to "corrosiony" issues.
Since Pyrodex has added chlorates (an old time trick used as early as 1800), once fired and combined with moister, it can create hydrochloric acid.
This acid is the reason Pyrodex can etch stainless barrels. The result is, as more water vapor is thrown into the residue, the worse the problem;
not only because of water-induced rust, but also from acid etching.
note that acid etching is peculiar to Pyrodex, and not Real Black.
The combustion of Pyrodex, T7 or Black Powder comes under the heading of Exothermic Organic Chemical Reactions.
Such reactions tend to be psychotically complex in the details. One example that comes to mind is the mixing of several no longer available
common household chemicals. There were multiple stages the mix went through, several directions the mix could take, with strange interim
results that could result in fuming toxic gasses, and finally end up in an unstable liquid that could make washing machines levitate.
Old Pharts amongst us may remember this debacle. Youngsters will just have to guess LOL .
But back to 777 and Pyro:
Most of what we care about is
- how much bang do I get and
- "what is gonna rot my gun" .
The "gross results" are expanding gasses and "byproducts".
Pyro gives more gasses (bang) than Black.
777 gives more gasses than Pyro
Both Pyro and 777 give somewhat different results from Black with regard to "what is gonna rot my gun" .
The detailed results get complicated. One can count on getting this, that and the other , but exactly
how much and how it affects the gun can vary just with humidity, let alone tempurature & other "stuff".
And in the case of Pyro and T7 the icky part will be perchlorate salts, hydrochloric acid and sulfuric acid and some other fouling.
Some folk don't seem to get much "icky stuff" , others get a strange and inexplicable "rust fungus" that seems difficult to kill off.
It may be the Exothermic Organic Chemical Reaction is just too complicated for exact identical repeatable results. And, frankly,
most people don't care as long as they can get a good bang and a "not rotted" gun.
pay attention to cleanining, use lots of water, use a good brass brush and don't trust to just "patch cleaning"
yhs
prof marvel