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100 yard zero shooting to the right at longer ranges?


LYNRDSKYNRD
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Like the title says. Rifle/ scope shooting dead on at 100 yards, 400 yards 3-4" right, 1000 yards wayyyy right. Made windage corrections at 1000 and I'm left at 100. Dialed correction out and dead on at 100. Elevation was correct for all distances. Any help would be appreciated.

Sent from my ADR6400L using Tapatalk 2

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Sounds like your scope is tilted in your mounts or the gun is canted. Try shooting a "box" at 100 yards and see if you get a square pattern. " 10 moa left and up. 10 moa right ect.. "

Or, strike a vertical line on a four foot length of butcher paper set at 100 yards. The line must be plumb. Put a target dot on the line for your aiming point. Start sending rounds downrange maintaining the same aim point (the dot) while dialing the impact up on the scope for yardage. Guarantee (based on your information) you'll watch the impacts move progressively right. If it does, the scope is out of plumb. No need to mess with lapping the rings with quality rings.

Check out the Hollands anti-cant bubble when you get it dialed in.

http://www.sinclairintl.com/optics/optic-accessories/scope-levels/holland-s-signature-series-scope-levels-prod42468.aspx

It really helps with consistancy in the extended ranges. The 700 yard target at my range I shoot at has a slight tilt. Most shooters don't know this and tilt the rifle without knowing. Pisses them off when they move back and forth between yardages and have to keep adjusting for windage on a calm day.

I matched my anti-cant with my scopes reticle with then used the anti-cant to level the scope to the rifle. My elevation tracks true. At least to 800 yards which is the max at the range.

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You can check your scope for cant at home, too (or, at least, I do). Run a "plumb line" somewhere across the room - I use a piece of string with weights on it, and hang it from the curtain rod. Set the rifle in a rifle vise, put a bubble level on the rail, and lock it in the vise with the rifle level aimed at the plumb line. If you look through the scope, you should be able to see at a glance whether your reticle is aligned with the plumb line or not (you may need to dial back the eyepiece focus a bit to see the string, but... you get the idea)

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Spindrift?

Spindrift is the direction the bullet will travel due to the rotation of the bullet from the rifling. A right hand twist will cause the bullets to rotate to the right and as it travels downrange it will at longer distance begin to travel up and to the right

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Just in case your scope is plumb and rails bubbled out and you're 100% positive that its nothing you're doing when you shoot then consider this....Where is your range located?

Example: When shooting at long ranges (Especially in the southern US ) you have to be aware of the direction you're shooting from/to.

Shooting a .308 rifle on a north-south line can cause you to be off easily 10" from the earth's rotation...add in spin drift to that and it can put you waaaay off.

Biggest problem from a shooter standpoint in long range that I have seen is lack of or poor follow through. Guys and gals jump off the trigger too soon.

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+1 pib45, my best bud has a "packer" from score hi. he loves it, i hate it... always out shoots me. On the thread topic, i keep it under 500 so i dont have the most experience with the fine details (coriolis effect and all that jazz), but ive always followed the rule that your scope (when you look through it) needs to be level to the world. palma shooters cant the heck out of their rifles to get a more ergo/comfortable grip and those guys can shoot. the scope cant bubble levels allow you to hold the rifle consistently when you dont have a nice flat horizon behind your target. just my .02

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I used to shoot a lot of High Power silhouette. So on this I am qualified to spek unlike action pistol where i am still new. The scope reticule not being lined up is a common problem. Most never see it because not many shoot past 200 yds. Once the scope is lined up if the problem persist you can try spinning 180 one of the scope mounting rings. this will tell you if the rings are off center. The worst possibility is that the scope rail or mounting holes could me machined out of line with the bore. All of this can be corrected with Burris Posi align rings and a kit of offset rings. Plus these rings hold a scope from moving unlike any other with no damage to your scope

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There is a difference between not having the scope plumb to the rifle and a canted rifle. The former usually has little effect unless you are doing hold overs, but the latter can made a difference in you POI. The further the shot, the greater the difference.

Your problem could also be trigger pull or a twitch which is pulling your shot off.

Edited by Graham Smith
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Consider this: At 400 yards with a 3mph wind, which is not much, will move your POI 3.5" with your load. At 1000 yards it's more like 26". Of course I don't know all your variables but just be aware that the wind causes more grief for the .308 than a lot of people think. Getting a .308 at 2557 fps to perform consistently beyond 600 yards requires a lot of work on your end. What kind of scope are you using. I have seen problems with some scopes at the top of the adjustment range having problems walking left and right. Assuming you are using a flat base (AR) you have to crank a lot of elevation to get to 1000 yards.

Just throwing stuff out there.

Jason

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I do a bit of 600 and 1000 yard shooting. And after 600 yards or so the .308 really is not the right tool for the job. Sure...I have shot them to a grand...the driving em out there is not the problem...it's the parking that becomes the issue.

You said you ruled out the wind. How did you do that? Did you have wind flags every couple hundred yards between you and the target? If not...I would first suspect wind.

If not then maybe your scope. Just because it is new does not me it is not hinky. I use NightForce, Leupold,etc., and have had bad upper end scopes that were bad out of the box.

I will go back and say that a .308 gas gun REALLY is not a 1000 yard rifle. What bullet are you using?

Here are some videos of me hammering some steel at a grand:

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168 Fed GMM 2557fps

That cartridge is really not suitable for 1000yds. It's primary operating range is 100-600yd. Beyond that it looses too much velocity to resist the wind and it's subsonic at or before 900yds.

If you want to shoot that kind of distance with a .308, you either need to go with a 155gr Palma bullet pushed to high velocity or with a 175-180gr high BC bullet. If you want factory ammo, look at the 175gr match or the Hornady 178gr superformance.

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I assume your rifle barrel has a right hand twist???

This is normal..it is as someone else says"spin drift"...I've shoot thousands of rounds over the last few years at 1000 yards in competitor...the rotation of the bullet imparted on it by the right hand riflings in the barrel is tremendous! If. I remember correct, a 1:8 twist barrel, pushing a bullet at 3000 fps, the bullet is spinning at about 230,000 rpm when it leaves the barrel...this rotational force will drift the bullet to the right at long distances..call it torque, P-factor..spin drift..what ever you wish..

...my 6Dasher needs 3/4 mins (7.5 inches) dialed in to the left in perfect calm conditions shooting at 1000 yards from a100 yards zero..about 2-2.5" at 600 yards...My 7RSUAM pushing a Berger 180 at 3000fps, takes abou the same..it's a 1:8:5 twist barrel...

So, if I've got a 5 mph direct cross wind at 1000, running right to left, I've got to dial in about 1 3/4 - 2 mins of wind age to the left to keep me in center..it's its a right to left wind, I've only got to dial in 3/4 min or so...

Edited by falconpilot
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