[Unclenick]

AFAIK, H110, alias Winchester 296. is what Winchester uses in their factory loads. It is particularly hard to ignite and requires both a magnum primer and a maximum roll crimp to get the start pressure needed for best performance. If you look at the Hodgdon web site (Hodgdon now distributes both H110 and 296) you'll see the warning not to lighten this particular powder by more than 3% from their load data. The reason is it can fail to burn properly when you leave too much case volume, with the result it fizzles all the gas out the barrel-cylinder gap. leaving a bullet stuck in the barrel. That can cause a disastrous subsequent discharge event if the next round does not fizzle. Reducing primer flame duration could do the same thing. It probably would only happen less than one time in a thousand, but there no point in being the one holding the gun when it does.

So, I would follow the recommendation for safety reasons as well as performance. And don't forget the firm crimp.