Click On Targets Below To Enlarge
Yesterday (April 3, 2014) was a great day for shooting in Western Montana. The high temperature for the afternoon was 55 degrees, humidity was right at 50-percent, and the light 3 to 4 m.p.h. breeze was mostly right in my face. During the entire 3 1/2 hour shooting session, I put a grand total of 29 rounds downrange - giving the rifle plenty of cool down time between shots.
Since I was shooting at 400...500...and 600 yards, far more time was spent walking downrange to post new targets...and to move the portable target board ever farther back...than shooting. The purpose of this test shooting was to determine how well the BDC reticle of the Hi-Lux Optics 3-9x40mm M40 Tactical Hunter printed hits at those distances.
During my earlier testing (and March 17th report on this blog), I had done my shooting at 100...200...and 300 yards, loading the .300 Winchester Short Magnum cartridge to get a .475 b.c. .308" diameter 168-grain boat-tailed polymer-tipped Hornady A-MAX bullet out of the muzzle at approximately 2,850 f.p.s. (2,874 f.p.s. actual avg.). The BDC reticle of the M40 Tactical Hunter has been designed around the ballistics of the .308 Winchester. The purpose of my testing has been to determine how compatible the BDC hold-over aiming marks are with other popular big game hunting cartridges. So, I picked up where I had left off during my earlier testing of the scope.
Sighted on at 100 yards, I found that the 200 yard aiming point printed hits on the average just about 3 inches high at 200 yards...and that the 300-yard aiming point would group, on average about 3 1/2 inches above point of aim at 300 yards. This was when shooting the 168-grain A-MAX at approximately 2,850 f.p.s. So, when I shot my first group at 400 yards, with the 400 yard hold-over of the scope's reticle, shooting the same load, I wasn't too surprised to find that it printed 4 1/2 inches above point of aim...and at 500 yards with the 500-yard hold over, hits averaged 5 1/2 inches above point of aim.
I've determined that the continued rise above point of aim is due to shooting such a high ballistic coefficient bullet at a higher velocity than typical with a .308 Winchester. The load I was shooting produced the ballistics of a .30/06.
I had a healthy supply of loads along that would put the same bullet out of the muzzle at 2,782 f.p.s., which is within the ballistics of the .308 Winchester. A couple of shots at 100 yards allowed me to tweak the scope to put hits "dead on" at that range. Then I went to the 400 yard target board, using the 400 yard BDC mark, and my first three shots printed just 2 1/2 inches above the bull. (Center-to-center, the group went 2.550" across - shown at right.)
At 500 yards, using the 500 yard BDC hold over, my group opened some - to 3.826" center-to-center - shown at left.. Now, I'm not complaining at all. After all...we're talking about shooting at 500 yards...and even with the scope at 9x...that tiny 1-inch dot in the center of the target is pretty much covered up by the aiming mark. At that range, I was basically holding as close as I could to what I felt was the center of the target. As you can see in the accompanying photo, the hits were a bit more scattered...but all would have taken the game being hunted - at 500 yards.
I had kind of forgotten what it was like to shoot at 600 yards. To walk out and move the portable target board to 600 yards...walk back to the bench...shoot the first shot...then walk back out to see where it hit...then back to the bench to shoot two more shots...and to retrieve the target and target board after the last shot...means having to walk 3,600 yards - just to shoot those three rounds at that distance. That's more than 2 miles of walking. My first shot at 600 yards had been 2.8" below the center of the target. The second round printed on the outer lower left edge of the paper, 5.115" from the center of the bull. And shot No. 3 printed at about 2 o'clock, 2.115" from the center of the bull. On average, the three hits were less than 3.4 inches from the center of the target - which is outstanding.
Now, it looks as if I am faced with one more long afternoon of long range shooting...to determine where those M40 Tactical Hunter longer range (400 to 600 yard) BDC hold overs do put the hits pretty much on when shooting at 2,850 to 3,050 f.p.s.
It's a Dirty Job...but someone has to do it! - Toby Bridges, Hi-Lux Optics