Bullet moves progressively to the right

[Brians356]

Have we come up with the answer

OP yesterday posted "... even in the wind and with my sketchy ability managed a 3" three shot group, no drifting to the right. Appears the problem was with the eight twist and the 139 SST."
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[Ccrider]

OP yesterday posted "... even in the wind and with my sketchy ability managed a 3" three shot group, no drifting to the right. Appears the problem was with the eight twist and the 139 SST."
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That’s funny. He had not worked the load up with the 139 Ssts.

 

[Brians356]

That’s funny. He had not worked the load up with the 139 Ssts.

OP: "The particulars: .280 AI, 139 SST ... "
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[SKWERLZ]

Have we come up with the answer

Yes
Bullets were based, not woke.

 

[markT]

Same as this bus. I could have sworn I saw Rosie O as it passed but couldn’t get camera going.

 

[ebb]

i thought that the only way this happened very much was scope bases not aligned with bore.

 

[jelenko]

Couldn't wait for tomorrow morning. Loaded five each different loads of IMR 4831 powder (using Hornady Book) and the 162 match. Fastest load put 3 in half inch at 100 yards Using new Ballistic Data moved to 500 yards.
It's South Texas and it's 100 degrees and a 14 mph wind coming in at one to one thirty. At 500 there are a number of Mesquite tree wind flags and I'm watching for the lull, it happens at least once a minute. Held dead center, shot dead center and even in the wind and with my sketchy ability managed a 3" three shot group, no drifting to the right. Appears the problem was with the eight twist and the 139 SST. Excessive RPM for that bullet, maybe too fast, 3100 fps? I will load up more of the 162's for the morning but happy with the way things are going.
Also had level on scope but it seems I was holding rifle level already.
Thanks for the comments
Robert

At 3100 fps and 8 twist rifling, the bullet is spinning 279K rpm. Not particularly fast.
According to JBM Ballistics, a bullet [H75 HPBT] with 3100 fps from an 8 twist drifts ~ 1.5" due to spin at 500 yards.

 

[spudgun]

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

For what it's worth.
I tried the SST bullets and did not care for them. They gave me poor accuracy at 600 and 1000 yds.

If you have not tried another bullet, try the ELD's. I get my best accuracy with them.

I didn't read if you have tried other bullets.

 

[Riesel]

For what it's worth.
I tried the SST bullets and did not care for them. They gave me poor accuracy at 600 and 1000 yds.

If you have not tried another bullet, try the ELD's. I get my best accuracy with them.

I didn't read if you have tried other bullets.

Currently using the 162 ELD Match and it has made a large difference. Better in the wind and more agreeable with the 1/8 twist

 

[markT]

I just couldn’t help myself.