I can tell you from experience (I own a Ransom Rest) different ammo will produce much different results. If it's not match grade ammo it won't be a ragged hole at 25 yards, it will be much worse (most of the time)! Also, the difference in match ammo is different depending on the gun. The purpose of a Ransom Rest is to determine which ammo shoots best in your gun. And, believe me, it varies dramatically!