Ballistic calculator differs from range tests-Why?

[charliebrown1999]

Shooting my Savage Model 12 VLP 26inch heavy barrel caliber 243 Win using PPU 90gr SP ammo with muzzle velocity of 3100fps. Shooting at 200yds hitting 6inch plate. Had to dial .9 MILS of elevation to hit 8 inch steel at 300yds. Scope is Athlon Argos BTR 6x24x50 MILQuad FFP. Turrets are .1MIL increments. Hornady ballistic calculator says if zeored at 200yds your drop at 300yds is only 6.7 inches therefore you only need .6 MILS come up. Yet i needed to .9 MILS of come up to hit at 300yds. What am i missing?

 

[hereinaz]

zero not perfect
garbage in garbage out of calculator
scope turret dials more than .1 mil with every click
velocity wrong
BC is WAY off

I would start with a perfect zero at 100 and dial everything else. At 200 yards, you should be dialed into the perfect center with a group smaller than 2 inches on the 6 inch plate, otherwise your zero won't be good enough to match the ballistic data even if it is correct. At 300 yards you should be on the plate with a spread of less than 3 inches and wind won't take you off an 8 inch place.

 

[Ledzep]

Step 0: verify hardware (mounts, rings, etc.)
Step 1: Verify zero.
Step 2: Verify muzzle velocity
Step 3: Verify BC/Drag profile.

 

[SouthFLShootin]

Does the box of ammo say 3100FPS or did a chronograph say 3100FPS?

 

[Mauser06]

Does the box of ammo say 3100FPS or did a chronograph say 3100FPS?

Never heard of PPU so I goggled it. Looks like that's where 3100fps came from.


Seems more like plinking ammo than precision ammo....but I've never shot it. Maybe be the best thing since sliced bread that is more consistent than anything I can roll up...I don't know.



Like the others said, if you input guesstimations, you'll get guesstimations back.

 

[hlee]

Hitting a 6” plate at 200 yards, huh? Where on the plate? Knocking out the center? All over it? Low impacts? Just hitting the plate doesn’t mean that much, it‘s a 3 moa plate at that range. My guess is that your zero was not perfect and you had some error stacking that caused the apparent need for additional elevation at the longer range.