I have a DPMS LR308B which has an 18 inch barrel with 1 in 10 twist, cal 308. I am lucky enough that my local range has 1000yd matches, and in my first try I used 190gr SMK Bullets. Performance was pretty good, but I would like to hear Ideas for the most accurate load with this combination of barrel length and twist. thanks!

I had good luck with WW-748, IMR-4320...short barrels Normally do well with faster powders like WW-748, H414, IMR-4320, and IMR-4064 in the .308

WW-748 has given me good accuracy and lots of velocity in the .308 Ruger RSI that I had..

I only used 150, 165 and ocassionally a 180 gr. bullets in that short barrel with the limited case capacity of the .308...

Thanks Ray!

Short or long barrel, RL15 is the best powder I've found in the 308... the US military thinks so too.

Try 40 to 42 grains of IMR-4064 with a 168 gr. Sierra Match bullet. This load range was extremely accurate in two 308's I owned. It produced some pretty slow velocities in the 18 in barrel, under 2400 as I recall but was stunningly accurate often producing same hole groups of 3 or 5 and 10 shot groups of under 3/4 inch at 100. I never tried heavier than 168's in either 308 but you might try 4064. For hunting I liked R-15, not that it wasn't accurate, just not stunningly so, and it produced far better velocity in the 308.

My FR-8 (17.5 " bbl) likes IMR-4198, 35 gr under a 150 gr Hornady SP seated at the cannulature. FPS may not be impressive, but accuracy is, and all the powder seems to get burnt.

I had a Mauser action with 18" barrell. My best stutzen, good hunter.
Favorites loads: 1) Fed. cases, Rem 9 1/2 primers, Reloader 7 - 41,5 gr., rem 125 gr. PSP with molybdenum, O.A.L. 2.560"
2) ELD cases, Fed 210 primers, IMR 4064 - 43 gr., Rem 180 gr. PSPCL w/Molybdenum, O.A.L. 2.717"
3) ELD cases, Fed 210 primers, WW-760 50,5 gr., RWS 180 gr. TUG bullets w/Molybdenum, O.A.L. 2.808"

You may have some problems shooting an 18 " bbled 308 at 1000 yards. Even in a 24" bbl Factory Federal 168gr. Match will not always stay Super Sonic to 1000 yards.
Your best bet is to probably stay with the 190's with 4064 or Rl-15.
I have had good luck in a 26" 308 with 185 VLD's and Varget.
There is a BIG difference between the BC of a 180 Sierra MK and a 190 Sierra MK.
Several years ago Sierra changed the configuration of the 180 MK. The originals had the longer boat tail of the 190,s. The new ones have the boat tail like the 168's.

Palma Match shooters who must use bullets no heavier than 155 grains usually have 30 or 32 inch bbls, and load HOT.

I have 2 short barreled Steyr Scouts in 308. Both of them shoot 165gr Partitions with 46grs of Varget extremely well for such a light gun. Both have shot 3/4" groups at 200yds (not every group mind you), and one has shot this combo into 3/4" at 300yds (when the wind died).
Obviously you aren't going to be shooting 165gr Partitions in a match but you probably should try Varget. I get good velocity, about 2600fps with Varget. Other powders give higher velocity but not near as good of accuracy in these two.
WW-748 has worked well for me in several other rifles with longer barrels. But part of it's attraction was that it metered so well. I was loading a lot of 308 for Silhouette when I shot through a few kegs of 748.........DJ

168gr C/T's and 46gr Varget work well in my 18" barrel Rem model 7.

25 grains of Hercules 2400 workds real well in some short barreled .308s

If you want to keep using those 190's:
BL-C(2) From 37.9 grains to 44.5 grains
Remington 9-1/2 Primer

I would suggest a bullet weight of around 165 to 170:
N-550 From 40.7 grains to 48.9 grains
Remington 9-1/2 Primer

For awhile i had 2 308s . One was a model 7, 20 inch the other a styer, The styer was 23.5 I think. The shorter barrel for sure liked varget while the styer was sweet with RL 15