Canted reticle or spin drift?

[Tangodown911]

I was shooting with a friend the other day. Conditions were near perfect. Sun at 12 o'clock no wind, no shadowing, etc. He uses a US optics level mounted to his scope rail. and level the the cross hairs with a plum bob. At 100y his rifle was dead on. At 500y and 600y and further he was having to dial 1moa left, as his rounds were now hitting right. I also shot the rifle and experienced the same thing. The reticle looks square.

Rifle as a .5moa gun at those distances. He was using 175FGMM and some hand loads with 175SMK as well.

I was figuring spin drift was no more than .3moa at those distances. So what do you guys think? What have you experienced.

 

[gme]

Re: Canted reticle or spin drift?

There could have just been a trickle of wind, it's hard to see when it's that light, canted reticles are not that uncommon, best way to check is to go back to 100 yards, set up your plumb bob and a horizontal level line use the intersection as your aiming point and shoot it while dialing up the elevation, go at least 30 MOA or so and see if the shots are tracking straight up or going off at an angle, just did this with a friend yesterday and discovered his scope was tracking almost 2.5" right at 30 MOA. The other possibility is the scope is not centered directly over the bore

 

[Osmosis]

Re: Canted reticle or spin drift?

If it is tracking off center do you just account for it in your adjustments or is it new scope time?

 

[bowhunter_0311]

Re: Canted reticle or spin drift?

This might help with the canting part.

http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=2189771

 

[slowr1der]

Re: Canted reticle or spin drift?

I have this same problem with a Nikon Monarch I have. At 100 yards, it tracks perfectly as adjusts exactly where I want it to. However, as I move further out, it seems to shoot left some, and I have to dial right. I'm not sure if it's just been wind, or how I have the scope mounted or what. I tried to level it, but it's making me question my installation. This also throws me off with the BDC reticle as it seems to hit off to the side a little.

 

[LoneWolfUSMC]

Re: Canted reticle or spin drift?

Run a 100 yard vertical tracking test.

Spin drift is not the issue.

 

[Arbiter]

Re: Canted reticle or spin drift?

There's always wind...

 

[Shireman]

Re: Canted reticle or spin drift?

instead of the plum bob way to level a scope, ever tried a feeler guage instead? I have found that it is much easier to get your scope "exactly" level.

Place the feeler gages on your base until your scope is flush and no gaps on either side. gently tight down rings while removing guages.
works like a champ.

not trying to redirect the subject, I have just been surprised at how many people dont know about this method.

 

[VKC]

Re: Canted reticle or spin drift?

I agree, run a vertical tracking test. Also suggest getting an anti-cant device. But, I think spin drift could be a factor at 500 to 600 yds, you could be getting about 0.3 to 0.5 MOA of spin drift. Take a look at JBM ballistics and do the calculations yourself. I think that is fairly accurate from my actual shooting experience. The rest, who knows, just have to eliminate the other factors, and you'll know.

 

[LawnMM]

Re: Canted reticle or spin drift?

Wind.

 

[BattleAxe]

Re: Canted reticle or spin drift?

Sounds like wind. Remember that the round doesn't travel in a straight line it travels in an arc. While there may not be any wind at ground level there may be some up higher (in the bullets path) that you can't feel.

 

[Killswitch Engage]

Re: Canted reticle or spin drift?

wish i had that facepalm picture everybody puts up.....get ya some spin D....

 

[KTDLS7]

Re: Canted reticle or spin drift?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LoneWolfUSMC</div><div class="ubbcode-body">Run a 100 yard vertical tracking test.

Spin drift is not the issue. </div></div>
^ ^ ^ ^ + 1 ^ ^ ^ ^

Check out this link for vertical tracking:

http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/ScopeChecking/

Note: Lindy is advocating tracking 4', NOT 6" (1/2 of a standard 100 yd rifle target). Also, check your distance to target.

Regarding wind, there may be no detectable wind at the firing line, but there can be wind down range.

Kevin

 

[turbo54]

Re: Canted reticle or spin drift?

I've never shot paper at over 750 yards, but I've never knowingly experienced "spin drift". Maybe there is just always the right amount of wind to counteract the spin drift?

Using the "feeler gage" method on Leupold VX-III LR, three NF NXS and a Bender PMII, I've always been dead center (laterally) from 100-750 yards in low wind conditions.