I need to get my wife a good deer hunting rifle. I will use one of my AR-15 lowers. Would a 6.5 Grendel or a 300 blackout be better for her? Thanks

Is she a good shot? How far are you shooting? Of the two, I’d lean to the 6.5 but under 200 they’ll be pretty close.

She is a real good shot with an AR-15. Most of our hunting would be less than 200 yards. Ammo seems to be more plentiful for the 300bo. Thanks

.300BLK w/110gr. 'X' type bullets (especially if suppressed) within 200yds..

6.5 Grendel w/120-123gr. expanding bullet will also work well (shoot flatter, hit 'harder'.

Thanks

I was deciding between the two for a rifle for my kids. Ended up with the blackout. So far so good. Son shot his first with it this year a javalina at 82 yards. I also shot a javi with it. 125 grain hand loaded nbt’s. We will get a deer next year.

I would add 6.8 SPC to your list. Check out the ballistics, upper receiver and ammo availability of all three, then make the choice that best suits you and her.

Go for BO with 1:10 twist.

Not an AR, but I am seeing plenty of 6.5CM ammo over here east of Big D in Atwoods & Walmart...Bought a 6.5 CM in a TC Compass II as Santa's gift to my self but have not had a chance to shoot it yet...staying tooo busy with the BH 's antique sales keeping me chasing auction pieces she's won from Dallas & north to just short of Longview.
Ron

6.8 is an excellent AR-15 upper for deer for that distance

Rick I see you’re in Emory , are you a Fishing Guide?

IDK about Grendal but I can tell you I have shot these pigs in February w a 300 BO bolt gun

197
187
225
227

Shots were from 60-105 yards

Those are just the ones I weighed, if it'll take down a 200 pound pig, it'll take down a whitetail

Not any more. I retired about 5 years ago.

Thanks for the response guys. I have decided to go with the 6.5 Grendel.

There's a feller in these parts, last of Wilson, who came up with a cartridge that goes the Blackout some better. He calls it the .300 HAM'R.

I agree with Nolanco the 300 Ham'r is what I would choose for a new build. The only advantage to the other calibers you referenced is box store ammo availability and price versus the Ham'r.