I tend to use Winchester, Remington or CCI primers in my 9mm and 40 S&W loads since the Federal primers flatten at much lower pressures. I reserve the Federal primers for my light revover loads since all of my revolvers have lightened DA triggers.
They are not "recommending" so much as they are reporting what they used and the pressures they achieved when they used that measure of powder at that OAL. If your barrel/chamber/bullet shape allow, then you can always use a longer OAL.Hornady and Sierra recommend OALs shorter than 1.1" with their bullets.
This is true, but only if you begin at the "starting load" and work your way up. There are too many variables at work in any firearm to simply start at the max load with similar components and expect good things to happen. I know you know this. I greatly respect your input. I say this for the benefit of beginning reloaders.So loading to that OAL is perfectly safe.
I'll respond again tonight when I can get to a printed manual.