The ability detonate the targets arenít an energy issue as commonly thought. Itís mostly velocity with some contribution by the bullet shape. Successful Boomershooting is all about delivering a bullet accurately and with sufficient velocity.
In general terms you need to be able to deliver a bullet into one minute of angle (MOA) target. If you, your gun and your ammo have difficulty hitting a one inch circle at 100 yards at least once every three or four shots you will be very frustrated trying to hit 4"x4" boomers at 375 yards even with only a light breeze working against you.
With the right AR-15, ammo, and optics a .223 will work fairly well out to about 500 or 550 yards as long as the wind isnít too bad. A heavy, 20" (or longer), match grade barrel is required for good results. This is probably the most economical option but don't expect to detonate anything at 700 yards even if you do manage to hit something.
Accurate 22-250's and and other varmint guns do well out to 550 or 600 yards if there isn't much wind.
The most common Boomershoot rifle is probably a heavy barreled .308. But this round is starting to run out of velocity by the time it gets to the 700 yard boomers. People do use it successfully and it does provide a good tradeoff between economy, comfort, and accuracy. Don't be surprised if the wind causes more trouble than it does with the bigger guns pushing heavier bullets and that the 700 yard boomers sometimes don't go boom even with a solid hit.
A .300 Win Mag will give you ample velocity at the 700 yard targets and good wind bucking ability. The people that dominate at 700 yards are using guns in this class. You may pay for this ability with your pocketbook and your shoulder.
An accurate .50 BMG will reach out and connect with the 700 targets without difficulty. It's drawback is the price and that our range cannot tolerate these cartridges except at 500 yards and beyond.
Whichever rifle you choose you will need some quality optics on it. 10x or greater is recommended. You will want target turrets on it as well. Mil-dots are a nice to have but not required.
Ammo selection is an important as rifle selection. Black Hills and Federal both make excellent match grade ammo. If you are going to buy loaded ammo buy match grade. If you handload use only match grade bullets. Any of Berger long range bullets will deliver the desired performance. Hornady V-MAX and A-MAX bullets work well. Sierra Match Kings and Varminter bullets deliver great results too.
Research and final selection
If you are in the process of selecting a rifle download Modern Ballistics or some other exterior ballistics program to help you select your cartridge. Talk to your gunsmith or gun dealer about "target quality" rifles and optics.
See also the following web pages: