Questions for you guys.  I have a 16" ar with a 1/9 twist RRA upper.  Im looking into black hills for match ammo.  My question is....what is the difference between the 68 grain match hp vs the 69 grain match hp.  I know the bullet weight is difference but other than that, is one better than the other.  I have read and searched online but couldn't really find any info.   Thanks for any info

68gr is a Hornady bullet, and 69gr is a Sierra bullet. Both are premium bullets, but a rifle will show a varying degree of preference for one over the other. This is highly individual to the rifle, however in my experience Sierra Matchkings almost always work well, whereas sometimes Hornadys can be a little more particular. My older PRI Mk12 upper would shoot Hornady 75's into no bullshit golfball sized groups at 200, whereas my particular Stealth can barely hit a playing card at 100 with them. Every precision rifle I've owned will shoot SMKs into tiny groups.

You'll have to order a sample of both and see what your rifle prefers. Also consider adding FGMM 69gr to the mix, and BH 69 TMK. You'll likely find the FGMM 69 to shoot a hair tighter but the cost may not be worth it, and that the 69 TMK bucks wind better but may shoot groups inherently a tiny bit larger than the corresponding 69 SMK. Again, you won't know until you see how they shoot out of your individual setup.

Often it is the shape of the ogive, tangent, secant, hybrid etc.  The shape from the bearing surface to the nose(meplate).  Sometimes dif of flat base vs. boattail vs. VLD.  etc.  Also effects bullet run distance to the rifling, jam into the riflings vs x amount of space.  Some guns do better with one or the other.  Hybrid was developed to lessen the problem.

When I was shooting a lot of CMP matches with a Colt HBar, I found the 69 grain Sierras were more accurate, and more expensive than the 68 grain Hornadys. The Sierras seemed to be popular at the time.

I used the Hornady bullets for practice and the Sierras for matches.

I don't have any barrels that shoot the 68gr Hornady's particularly well. Which isn't to say that your barrel might not love them, but if I was playing the odds and had to choose I'd take the 69gr Sierra's.

Something to try whenever they come out (announced but not available yet) would be the Federal Gold Medal Match loading of the 73gr Berger bullet. Berger says that bullet is ok in a 1:9.