I've got a 9 twist barrel on a 16" RECCE and SGammo has some ADI with 69g BTHPs for under $12 box.
Any reason not to FO?

My local spots are still selling 55g AE for $10/box

Your 1:9 is going to marginally stabilize 69gr projectiles.

69gr is in the suboptimal range so they be accurate, they may not.

What are you looking for accuracy ? If so at what range ?

All in all that is a good deal , especially if your rifle shoots it well.

If you are just looking for range fodder.... buy some Fed. 50gr Tipped Varmint ( PSA ) and GECO 55gr FMJ ( SGAmmo.com ).... VERY accurate for the price.

Cheaper then your 12 bucks by a least $4 / 20.

I have a relatively inexpensive 1-4 optic so I'm hoping for decent groups out to 300yds.

I know there are mixed reviews on Matchkings for social circumstances...

Hi,  

IMHO order if you want to try them.  I was going to order  some from SGAmmo but the local Cabelas had them on sale for less than eleven dollars a box.  Having shot 55's at 300 yards the wind does tend to blow them around.   For mixed use the 75 gr.  HPBT Hornady 5.56 TAP superperformance is had to beat,  my son's16" RRA carbine same twist 1-9 was regularly ringing a gong at 600 yards with it on a windy day Using a 4x TRIJICON ACOG.

Best Wishes:  

I get about 1.5" 10-shot groups at 100 yards with the ADI 69 SMK out of my 16" Rainier Select barrel.  Velocity is in the mid 2600s.  To me it is pretty comparable to the Prvi 75 grain match.  Not terribly accurate, but decent for the price.  The ADI 55 SBKs are more accurate in all of the barrels I've shot it through.

My 18" Daniel Defense mid length loves the 69gr, consistently shots 3/4" 5 shot groups at 100yds.

You should take the challenge then!  That would be about 6th place best groups on the entire site.

http://www.ar15.com/forums/t_16_17/51___ARFCOM_1_MOA_ALL_DAY_LONG__Challenge_.html

The bottom line on this ammo, is there isn't anything even close in price (55 cents a round), that uses a sierra matchking.

The closest "match" ammo in price would be the PRVI 75gr (50 cents a round), and I have shot a lot of that, and it is not that impressive, especially once you get beyond 300yds.  If someone is getting 1.5" 10 shot groups, this is likely the best "match" grad ammo at distance for the money out there.

The only argument I'd make, is that if you don't need to shoot past 200-300yds or fight wind, the only thing that will smoke it on price/accuracy comparison is the Federal 50gr VMAX loads, at 40 cents a round.  http://palmettostatearmory.com/index.php/catalog/product/view/id/4550/category/4488/

Don't know how accurate it is in my JP, since it doubled and tripled when I was trying to chrono it. Made an average day at the range much more exciting...