Based on 15 years of shooting prairie dogs, I suggest Remington 50 gr HP as a very accurate and inexpensive bullet with a 1:14 twist barrel. That bullet worked in a Thompson Contender, AR 15, and S&W 1500 rifle.
The 55 gr FMJ bullets (got a great deal on 2,000 full case) only worked in AR 15 with 1:9 twist. These bullets were tumbling at 25 yards with a 1:14 twist. Awesome knockdown power, but the pattern size exceded
FOUR FEET at 100 yards.
Several friends have searched for the "golden 223 bullet" and finally agreed that the Remington 50 gr HP gave the best results. There is an additional bonus to this bullet. You can run lubed cases thru your progressive reloader, tumble loaded ammo for 30 minutes, and be ready to shoot. The Rem hollow points are to small to fill with tumbling media. I have tumbled loaded ammo to remove case lube for 20+ years without a problem.