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I suggest:
The 4350 designation is an old military spec.The number gets used by multiple powder manufacturers(Hogdon,IMR,Accurate,for sure)
There are also old surplus batches and newly manufactured batches.Plants close,businesses are bought and sold,etc. Each time we get a little different powder.We cannot count on the data being interchangable.Loading manuals change,too.Please be careful matching appropriate data to your powder.
In cases like the 7 mag,you have a big bottle to put powder in and a small bore for the pressure to be released.That means pressure changes can occur rapidly(as opposed to a round like the .308,it is more forgiving) The term is expansion ratio.
IMR 4350 is an appropriate powder,as I recall the Nosler 150 gr likes it.
One of the best tools you can buy for loading 7mm mag is an RCBS precision mic.
To just bump your resize die off the shellholder will make ammo you can shoot,but brass life will typically be short and you will see a shiny ring develop above the belt.This is a stretch mark,and if you cut the brass,you will see it has become very thin.A few more loadings,and you get head separations.
The precision mic allows you to take a measurement of your fired brass shoulder,and adjust your dies for a precise amout (.002 is good) of shoulder setback in your rifle.
About $100 will get you a chronograph,I have a ProChrony.They are a very useful tool.
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