Just acquired a Colt H-Bar Competition Target Match with 20 inch barrel. I was just wondering  if any one has any recommendations on bullet weights to use in a 1-9 twist barrel? Am I correct in saying that the lighter grain bullets will perform in a barrel with this twist rate? What is the heaviest bullet wt recommended?
Thanks in advance for any advice.

Pretty much whatever shoots well.  I assume you are looking for max accuracy.  If you want the heavier bullets then try the 75 grain BTHP.  If they don't shoot well, try the 69 grain BTHP.  If you want the lighter bullets, try the 55 grain Vmax.  There is also a 52 grain BTHP match load.  If you really want light weight, try the 40 grain Vmax.  You're just gonna have to try different kinds and see what shoots well for your rifle.  The 1-9 will shoot pretty much anything you can purchase off the shelf.  Try different weights and brands and see what works for you rifle.  Different rifles like different bullets/brands.

Ditto on the above. Anything from 40gr to 77gr (although the latter is pushing it) should work fine in your rifle.  Some people report less than satisfactory results with the 75-77gr weights, others have had better results. I have had excellent results with the 75gr Hornady out of my 20" Bushmaster (1:9) up to 200 yds (longest range I can use).

The most surefire bets would be those below 70gr (the Sierra MK 69gr and the Hornady 68gr are favorites among the 1:9 crowd for target shooting).

From 40-69 gr you are set to go, then just try the heavier ones and see for yourself.

yoyo


I have had great luck with 55gr berger and 55gr
hornady and 50 gr speer tnt  good luck



vinniedablade