Effective range for 7.62mm...

by Byron, Monday, July 18, 2016, 09:51 (2989 days ago)

We had to opportunity to attend an open range day at the Spearpoint Ranch yesterday and shoot as much as we wanted to at targets from 300 out to 1400 yards spaced at 100 yard increments. I was shooting a Savage "tactical" rifle in 7.62mm shooting 168gr milspec boat tail bullets and my son shooting his AR30 in .300 WM with 190gr Matchking bullets. Both rifles are sub MOA shooters at 100 yards, hot,cold, clean or dirty.

The atmospheric conditions in the morning were perfect and both shots from both rifles were leaving clearly visible traces in the air heading down range.

The 7.62 was absolute dead bang at the 800 yard mark easily hitting 5 for 5 on the 12x18" plates. Past 800 yard it fell completely apart and I never hit a single plate with it past 900 yards out of another 30 or 40 shots.

The trace clearly showed a smooth looped line to the 800 yard targets and then started a big corkscrew that maybe got yaws of 20 to 50 feet across at 1000 or so. It was difficult to judge distance out there but clearly the bullets had gone transonic and became completely unstable. I would have never guessed it would be so dramatic. The rifle/round was shooting probably 6-8" groups at 800 and at 1000 probably opened up to 20 feet or more. Crazy. I would not have believed it if I had not seen it.

The .300 WinMag and 190 gr Sierra Matchkings held up just fine and the silhouettes at 1400 yards were in grave danger with hits maybe half the time even when the wind came up. Still, the bullet was clearly stable all the way out there.

Looks like it time to order a bunch more of the 190s...

Byron

http://www.spearpointranch.com/dogs.html
http://www.matchgradeprecision.com/precision-long-range/