7MM MAG 24 or 26 inch barrel

[Screwey1]

I am getting a new barrel on my 7mm Rem Mag and am not sure what length to get. I used to use it fo an eastern whitetail rifle, but now want to use for long distance muley and antlope, hence the rebarrel. If I was not going to change my load , I would keep with a 24", however, I have aquired a boatload of Hogdon retumbo that I want to start load developement with this powder. I have not settled on bullet weight yet, will most likely be 140 to 168 area.
My concern and question is , when loading the lighter bullets and approaching max load, will I be throwing unburnt powder on the ground with a 24 inch barrel? Retumbo is a pretty slow burner.
Any thoughts?

 

[Screwey1]

Wow,should have looked around more because, boy did I put this post in the wrong place.

What I meant to say was Hi everyone!
I am a hobby shooter. I shoot relatively accurate out to 1000 yards. Still learning the wind!
I live in northeastern U.S. but hunt out west a lot.
I enjoy handloading, hunting and of course shooting.
I like to hunt at either long distance or right up close using a longbow.
For those critics that say people have no business shooting animals at distances, I hunt primitively close too.
Both are challenges and isn't that what hunting is supposed to be?

Look forward to the opinions and thoughts of like-minded individuals.