Congratulations on the 527 Score! My observations hav been they do benefit from a little breaking in & tweaking of the extractor. Expect you will be very pleased with the 6.5 Grendel. What barrel length or model did you find?
When I put my 1st 6.5 Grendel together a little over 6 years ago I thought the only thing I may like better in the way of a deer rifle was if she was necked down to 6mm.
Could not say the 6mm is better, though I really do like the 6mm ARC. She is new to me so of corse it is my favorite. To put this in context though, I have a 300 black out that never really has excited me much as well as a 7.62 x 39 that has yet to catch my interest. Really does boil down to different strokes for different folks. On the open parries of windy South Dakota the sleeker more wind forgiving sexy 6mm hunting projectiles has been a nice edge to have for my hunting style.
Suppose Ill do well to keep in mind the planes of North & South Dakota, Nebraska along with Kansas amount to a very small portion of the USA hunting population. Thus the rifle builders tend to focus on the more populous needs from coast to coast. I am guessing a lot of folks have seldom if ever had an opportunity to take a deer at distances further than 125 yards.