gregrn43
At the time, in the Hay-day of White, Pyro "P" was the recommended powder by Doc. Not even sure if T7 was available then.
I should also tell you that there may be some issues that come with T7 and their certainly are some advantages. The issues.... Underclocked's infamous "crud ring" a deposit forming a hard deposit ring near the bottom of the barrel in the charge area. I am not really sure why this ring appears for some shooters and not for others. I personally believe it is tied to the way you treat your barrel but I can not prove it. I have several different inlines and sidehammers - I shoot T7 in all of them and have not significant "crud ring" in any of them - again I do not know why.
I do not shoot "pyro" so I do not no if you swab the barrel after each shot with it or not, but with T7 it is a really good idea to do so. I use pre-moisten windex patches at the range and a simple spit patch while hunting. Speaking of hunting I am normally able to load 4/5 shots without swabbing if I needed to.
If you are going to try some T7 - I would suggest T7-3f for #11 ignition. I shoot a 209 breech plug - so I do shoot T7-2f, but more than a handful of people have reported that it burns cleaner and I beleive it is easier to ignite in the really cold weather.
And I agree - White's are really a quality ML - they are built like tanks, simple maintenance, easy cleaning, and they shoot great.