I was planning on getting an upper for my RRA AR-15 in the 6.5 Grendel for my very petite daughter to use next season for deer. I figure I'll limit her to 200 yards at this time. I mentioned to the guy (very knowledgeable) behind the gun counter at a local store. He mentioned I should consider the 300 Blackout since the range won't be overly long. Having never used any of the cartridges in the title I would think the 6.5 Grendel would be the most versatile followed by the 6.8. What are your thoughts on the three and what would you choose for deer out to 200 yards? What are the advantages and disadvantages of the cartridges? Recoil is also a factor.

Thanks