Hi all,
I've been a lurker on-and-off for these forums for several years now, but I've run into a conundrum that's convinced me to make an account and ask for some help. I recently took my hunting rifle, a 300 Win Mag, out to the range to check the zero and do some mid-range trajectory validation. The weapon is currently averaging 3/4" groups with my handloads, which I am satisfied with for how difficult it is to shoot such a light gun without any of the conveniences of my target rifle setup. After verifying that it was zeroed at 100 yards, I shot at a 10" steel plate that I had set up at 500 yards (verified with a Leica Rangefinder), and missed it entirely. There was no wind on the range, and I couldn't see any splash from the sides or above the plate, so i assumed it hit low and was obstructed by the mound I had placed the target on. I prepared a firing solution using both Hornady's 4DOF calculator as well as my Kestrel 5700 with Applied Ballistics before coming to the range, and double checked my scope turret to verify I had dialed 7.5 MOA. Firing again, half-way between center and the top of the plate, and the bullet impacted the very bottom edge of the plate. Today, I took my rifle out to the range and performed the same task, with the EXACT same results. The rifle is properly zeroed at 100 yards, and impacting over 1 MOA low at 500 yards. I simply cannot understand what is causing this, because I have done everything I can think of to eliminate unknowns and reduce the odds of equipment failure. I am loath to waste expensive powder, bullets, brass, and carefully reloaded ammo blindly. By my understanding, the only way for this to be (assuming firing system is not to blame) is that my velocity is somehow ~160 fps slower than my LabRadar and Garmin are measuring, or I have the WORST batch of Berger 215 Hybrids known to man, performing at .180 G7 BC instead of the advertised .354 G7 BC. Any ideas?
Thanks
Environmental Conditions on both range days:
Elevation: 5500 feet
Station Pressure: 24.42 inHG
Temp: 51 F
Wind: 0-1 MPH from 2 O'clock
Humidity: 20%
Angle of Fire: ~3 degrees? (Range is Exceptionally Flat)
Equipment and Shot Conditions:
Rifle: Christensen Arms Ridgeline Titanium chambered in 300 Winchester Magnum (1:10 Twist, unsuppressed)
Scope: Nightforce SHV 5-20x56 FFP on Nightforce Steel Base and Seekins Precision Rings (Scope Height @ 1.95")
Ammo: Handloads; Peterson 300 WM Long Brass, 79.0 gr VVN570, Berger 215gr Hybrid Target Bullets
Muzzle Velocity: 2970 FPS, ES: 21 fps (verified by LabRadar during load development and Garmin Chrono at both range trips)
TL;DR: Gun shoots 3/4" groups from cold-bore, cold-shooter regularly at 100 yards. Gun shoots ~1.1 MOA lower than predicted at 500 yards. Equipment and Ammo very unlikely to be at fault, verified firing solution with Hornady 4DOF and Kestrel w/ Applied Ballistics, verified zero and velocity every range trip. Help
.
I've been a lurker on-and-off for these forums for several years now, but I've run into a conundrum that's convinced me to make an account and ask for some help. I recently took my hunting rifle, a 300 Win Mag, out to the range to check the zero and do some mid-range trajectory validation. The weapon is currently averaging 3/4" groups with my handloads, which I am satisfied with for how difficult it is to shoot such a light gun without any of the conveniences of my target rifle setup. After verifying that it was zeroed at 100 yards, I shot at a 10" steel plate that I had set up at 500 yards (verified with a Leica Rangefinder), and missed it entirely. There was no wind on the range, and I couldn't see any splash from the sides or above the plate, so i assumed it hit low and was obstructed by the mound I had placed the target on. I prepared a firing solution using both Hornady's 4DOF calculator as well as my Kestrel 5700 with Applied Ballistics before coming to the range, and double checked my scope turret to verify I had dialed 7.5 MOA. Firing again, half-way between center and the top of the plate, and the bullet impacted the very bottom edge of the plate. Today, I took my rifle out to the range and performed the same task, with the EXACT same results. The rifle is properly zeroed at 100 yards, and impacting over 1 MOA low at 500 yards. I simply cannot understand what is causing this, because I have done everything I can think of to eliminate unknowns and reduce the odds of equipment failure. I am loath to waste expensive powder, bullets, brass, and carefully reloaded ammo blindly. By my understanding, the only way for this to be (assuming firing system is not to blame) is that my velocity is somehow ~160 fps slower than my LabRadar and Garmin are measuring, or I have the WORST batch of Berger 215 Hybrids known to man, performing at .180 G7 BC instead of the advertised .354 G7 BC. Any ideas?
Thanks
Environmental Conditions on both range days:
Elevation: 5500 feet
Station Pressure: 24.42 inHG
Temp: 51 F
Wind: 0-1 MPH from 2 O'clock
Humidity: 20%
Angle of Fire: ~3 degrees? (Range is Exceptionally Flat)
Equipment and Shot Conditions:
Rifle: Christensen Arms Ridgeline Titanium chambered in 300 Winchester Magnum (1:10 Twist, unsuppressed)
Scope: Nightforce SHV 5-20x56 FFP on Nightforce Steel Base and Seekins Precision Rings (Scope Height @ 1.95")
Ammo: Handloads; Peterson 300 WM Long Brass, 79.0 gr VVN570, Berger 215gr Hybrid Target Bullets
Muzzle Velocity: 2970 FPS, ES: 21 fps (verified by LabRadar during load development and Garmin Chrono at both range trips)
TL;DR: Gun shoots 3/4" groups from cold-bore, cold-shooter regularly at 100 yards. Gun shoots ~1.1 MOA lower than predicted at 500 yards. Equipment and Ammo very unlikely to be at fault, verified firing solution with Hornady 4DOF and Kestrel w/ Applied Ballistics, verified zero and velocity every range trip. Help
.
