bullet stability

[drpbroun5]

How do I tell for certain if a bullet is stable or not? I am starting to work up a load for my 300 Win Mag. It has a fairly slow twist at 1 in 10 3/4". I'm told by the custom rifle maker that it will stablize a bullet up to and including a 215gr Berger. I know Bryan Litz's recommendation. I have loaded one ladder test done at 100 yards in the tagget at 100 yards were round.with H1000 from 75.0gr to 80.5gr in 0.5 increments with one round per charge. I only found one node that was +/-0.5gr. All of the holes at 100 yards were round. Since all of them were round, I think that the bullet is stable inspite of it being a marginal twist rate. Am I thinking correctly? I greatly appreciate your thoughts.
Thank you.
Paul

 

[drpbroun5]

I goofed!

Between the time I typed this question and when I posted it, a gremlin got into this post. I do not know how to delete it. I re-posted a corrected one the is later than this one. Please disregard this post and look at the better one Thanks.