Bullet moves progressively to the right

[Riesel]

The particulars: .280 AI, 139 SST, 3100 FPS, 24X scope, 26" barrel with suppressor. No wind, 7AM, 79 degrees 85% humidity.
Sighted in at 100 yards, dead center on 8" gong at 300 yards with a slight downhill. Move uphill to 500 yard on gong measuring 12" wide by 22" tall. 8" MOA dialed in. First two shots, elevation dead on, caught right edge of gong. Held on left edge and hit gong dead center. I'm thinking I may be canting my rifle. The scope mounted using levels. What else should I address?
Thanks'
Robert

 

[Bill Norris]

A tall target test will tell you if the scope is canted or if you may be canting with your hold. The bullet will move in the direction the cant is applied.

 

[Coyotefurharvester]

Your elevation would be off also if canting the scope. Did you dial back down and shoot a confirmation round at 100?

 

[6MMsteve]

could also be torque maybe, but the tall target test is first like Bill said...Is the Horny sst considered a stable accurate pill also

 

[Southern shooter 59]

On my rifles, spin drift becomes obvious past 300 yards.

 

[wboggs]

On my rifles, spin drift becomes obvious past 300 yards.

That seems like a lot of spin drift at 500

 

[Riesel]

Your elevation would be off also if canting the scope. Did you dial back down and shoot a confirmation round at 100?

No, didn't have enough loaded as I was load testing

 

[JoeDuke]

Try it a couple more times. "Just in case" the wind may be moving your bullet.

 

[Coyotefurharvester]

Repeatable stacked divergence, grip, torque, rifle support, spin drift. If you aren't straight behind the rifle right or left poi is a likely result. Or an optic issue.

 

[jdh47]

Barrel fluted and button rifled? What contour? Wind? Light barrels move as they heat. Ed Shilen did tests and said fluting was not a good idea for button rifled barrels so he wouldn't do it to his. Sounds like it's heating up and walking.

 

[BoydAllen]

What flags did you have out?

 

[nmkid]

What flags did you have out?

64 Million dollar question.

 

[Riesel]

It's a non fluted X-Caliber 1:8 twist heavy sporter barrel. I had flags posted at 50, 300, and 450 yards and flags indicated dead calm. I'm taking more test ammo and a level for my scope. The winds have picked up again as they normally do for the afternoon so a retest may be tomorrow morning.

 

[CharlieNC]

When you change from downhill to uphill, canting can definitely be a problem. You need to use a cant level for those types of conditions to use routinely, and to address this particular problem.

 

[Ccrider]

No wind,

This I find hard to believe.

 

[gunsandgunsmithing]

This I find hard to believe.

It is a rarity but if the flags said so, along with mirage and anything else like leaves grass and the hair on your neck...Well, hard to argue with that but I would've guessed wind first too and it wouldn't take much at all.

 

[Ggmac]

are you shooting east to west , north to south , other ?

 

[Ccrider]

It is a rarity but if the flags said so, along with mirage and anything else like leaves grass and the hair on your neck...Well, hard to argue with that but I would've guessed wind first too and it wouldn't take much at all.

Sometimes I believe there is wind we don’t see, even with flags; especially at longer distances.

 

[BoydAllen]

It's a non fluted X-Caliber 1:8 twist heavy sporter barrel. I had flags posted at 50, 300, and 450 yards and flags indicated dead calm. I'm taking more test ammo and a level for my scope. The winds have picked up again as they normally do for the afternoon so a retest may be tomorrow morning.

I will be interested in your results.

 

[John Beauchamp]

I shoot on two different ranges where the wind shows up in layers, so if your flags are not at the same level as the bullet path it could make a difference. I have seen a no wind at 3 ft off the ground and something else at 6ft. I have seen it blow in opposite directions at different heights. Thats why sometimes the flags will say one thing but the target says another.