Rafter,

It seems a lot have people are unaware that IMR 3031 was developed for .30-'06 class cartridges, and it has been doing fine for 76 years.

If it ain't broke, don't fix it!

My concern would be why a rifle would shoot 1" with only one load and 5" with a similar load. Sounds like a bedding issue (hopefully), or a barrel problem (hope not).

Good shooting.