Some guys shoot 3-shot groups for load development. Others shoot 5-shot groups or 10-shot strings. Sierra Bullets is the best for testing projectiles. Sierra was testing its 175gr HPBT MatchKing in an underground tunnel. The results are shown above — a FIVE THOUSAND Round group! 500 Shots for 0.82 MOA Group at 300m (328 Yards)
Sierra’s trigger-pullers sent five full boxes bullets downrange at one target. The photo shows 500 shots taken in a 300 meter tunnel. The raw group size is approximately 3.13 inches from edge to edge of farthest shots. This is as shown on the calipers’ metal linear scale. Add a.308″‘ nominal bullet diameter* to get 2.823’s on the digital readout. At 300 meters (328 yard), you will see a group of 2.823’s. One MOA at this distance, 3.435”, is the 500-round group. This is 2.823 divided with 3.435 or 0.82MOA (0.8218 MOA). This 500-round group was shot as part of a pressure/velocity testing for a commercial customer. The cartridge was.308 Winchester and was loaded at 2.800’. Reloder 15 was used for the powder. A 26-inch barrel was shot from a return battery rest. The gun was cleaned after each 125 rounds, and there were two foulers. What do you think? Could you beat this group with 500 rounds of ammunition from a bench? One Facebook poster joked that the 500-round group was absurd. Everybody knows that anything less than 1000-round group is a waste of time, and statistically irrelevant.” Sierra’s 300 Meter Testing Tunnel
Ever wonder where and how Sierra tests its bullets? The answer is underground in a 300-meter tunnel under Sierra’s factory, Sedalia, Missouri. The tunnel was built in May 1990. Sierra conducts live-fire bullet testing on its projectiles, as do most bullet manufacturers. Sierra’s 300-meter underground bullet testing facility is the longest of its kind. Sierra used to offer free access to the test tunnel in years past as part of factory tours. * To get an exact group size, subtract the TRUE bullet holes size. This is usually smaller than what the nominal bullet diameter is. E.g. A.308 bullet hole might appear on paper as.298. We are subtracting.308 because we don’t have the original target to measure.
