But in this case, a magnum primer may be appropriate. I say this because of all the irregularity mentioned by Road Clam. As former CCI employee Alan Jones points out, a magnum primer can improve ignition consistency when you have a lot of empty space in a case, and that is what this kind of load has. It's not that the powder won't light with a standard primer but rather that it needs a bit more starting pressure from the primer to do it with the same timing every shot. I know Tightgroup is supposed to be position-insensitive, but this is relative to other powders. If you put a pinch of it in a 45-160 case you are not reasonably going to get the exact same performance with it back over the flash hole that you will get with it up at the bullet base. You won't see the variation in Hodgdon's load data because the ballistic tech performs "the SAAMI twist" manipulation of the case to get the powder over the primer every time. That makes for the worst case highest pressure, which is why it is done.
In the 44 Magnum, you can see the effect for yourself if you shoot at a range that allows loaded guns to be pointed into the air. Mine does not, owing to another nearby range that had some rounds go over its berm and strike a silo a farmer was standing near. But if yours does allow it, it's a great way to test your load for powder position sensitivity. Tilt the gun up, then level it slowly to fire over your chronograph for every shot and see what the mean velocity and SD are. Then repeat, but tilting the muzzle down and slowly bringing it up to level with every shot.