T7 is more energetic, I bought some bottles when it was all there was. You can also easily use it in straight wall cases if you run out of
RE 777 -
here is a monster wall of text from Dutch Billhttp://www.cascity.com/forumhall/index.php/topic,56740.0.html
about 777 he wrote:
With Hodgdon we have Pyrodex and Triple Seven. The whole patented concept in Pyrodex was the use of sodium benzoate with potassium nitrate. But to get the two to react fast enough to make it a usefull firearm propellant they had to heave in something like 17 parts of potassium perchlorate. When the powder burns the potassium perchlorate simply gives up its oxygen and remains as potassium chloride. ANY chloride will be most corrosive in the gun.
The patent on Pyrodex ran out a few years back. Then the in-line ML hunting crowd wanted faster powders. A big push came when the plastic sabots came into use in the in-line ML rifles. That 17 parts of potassium perchlorate that was converted to potassium chloride causes a lot of grief with tight fitting sabots. The little crystals of potassium chloride are scattered to the bore. When you would push a sabot down the bore the crystals would embed in the plastic. So you would reach a point where you could not get the sabot down onto the powder charge.
So what we see in 777 is a change to sodium dintitrobenzoate sulonate. Think of it as going up a notch in benzoates. This dinitrobenzoate is HIGHLY reactive with charcoal. So there is no need to heave in a bunch of potassium perchlorate to "strengthen" the powder. This makes 777 a lot LESS corrosive compared to Pyrodex. When I checked the 777 on brass plates there was no surface pitting of the brass as with Pyrodex. Hodgdon's MSDS for 777 shows potassium perchlorate. From what I saw in my steel plate and brass sheet corrosion tests I don't think it has any perchlorate in it.
With this development of 777 Hodgdon can claim that it is an improved version of Pyrodex. Makes getting it onto the market a lot cheaper than going through it as if it is an entirely new explosive composition.
The thing about potassium chloride corrosion in gun bores is that a lot of times the average shooter would never know it is happening. You can get a lot of micro-pitting of the bore which gives the surface of the metal a frosted look. This comes up to bite the shooter if the shooter switches to black powder. BP fouling will then act as if it is welded to the bore walls. Simply because the metal's surface is so rough and pitted.
When Hodgon formulated Triple seven they greatly reduced of amount of potassium perchlorate
compared to the amount found in Pyrodex, about 17% in Pyrodex, based on the patent covering
Pyrodex. I ran Triple Seven against Pyrodex and the Swiss BP on mild steel plates and on sheet
brass and sheet copper.
The extent of surface leaching was the same with all three powders.
but the problem is this: the Fed MSDS for T7 shows potassium perchlorate.
It is a safety doc relied upon by firefighters, EMT's, doctors and even the "bomb squads"
If Hogdon spoofs the MSDS for any reason all hell can break loose, and I don't think they are willing
to risk losing their license over a little paperwork....
And I wrote a rather long and overly verbose monograph on the topic of cleaning
The use of potassium perchlorate as an additional oxidizer is the only way Hogdons was able to achieve the desired results.
here is the MSDS poop, as published by Hogdons:https://www.hodgdon.com/PDF/MSDS%20Files/Muzzleloading/Pyrodex%20SDS%20Sheet-2013.pdfhttps://www.hodgdon.com/PDF/MSDS%20Files/Muzzleloading/Triple%20Seven%20SDS%20Sheet-2013.pdf
oh and here is Mako's writeup on the chemistry of BP and Petroleum productshttp://www.cascity.com/forumhall/index.php/topic,41064.0.html
hope this helps