960 and 1310 yards w/6.5-284. Question

[BrentM]

In the first vid I shoot 960 cold bore 1 shot solution. Second vid is 3 shot at 1310. Both vids are same day and same spot. Later I checked zero to see if it was me or something else creating left side target hits. I was left .5moa and made the proper adjustment. I also zero'd for 100 instead of the normal 200 and noticed solutions needed me to reduce bullet speed by about 60 fps.

The question is two fold. Do you think the 960 and 1310 are off due to FPS error or should there be a two part solution in shooter for BC. I am shooting 140 berger vlds.


[ame=http://www.youtube.com/watch?v=MTfHp5fFNtk]Shooting 960 yards 6.5-284 - YouTube[/ame]

[ame=http://www.youtube.com/watch?v=dFsyKAUVIxo]Shooting 1310 yards with 6.5-284 - YouTube[/ame]

 

[Broz]

On the 1300 shot you definitely had a right to left wind. Probably 3 to 5? The dial up looks low, but the 900 shot was a little low too. So your MV could be a little strong or you could have a scope tracking off from the .25 moa a little as it seems to get worse with distance. Could be a little of both.

That's what I see from the video. But I was not there so it is hard to say for sure.

ps: the one that was on for elevation at 1300 I would say one of these 3 things. Bag collapsed under recoil, hot flyer from large ES, or a wind lift coming up the face of the canyon.

Jeff

 

[stomp442]

Are you accounting for spin drift and corriolis effect too?

 

[BrentM]

Thanks. I am leaning toward the solution FPS is not correct. I have a some shots at 1500 from the same spot that seem good on elevation, which is weird. I will try and get a short clip posted. The impacts are really hard to see and of course, are left.

Night Force scope. I have not checked .25MOA tracking. Need to do that.

I re-read my message. The zero was off by .5moa Left. I found that later when I re-zerod. I was playing with spin drift and wind read and noticed everything was still left. At the time I figured I just sucked, as usual. So if I had been shooting a L and R zerod rifle my guess is I would have been .5 to 1 moa right of my impacts. At this time was rifle was supposed to be zerod for 200. I am not sure why caused the Left issue. I suspect is from bouncing around on 4 wheeler for the past month. ??

On the 1310 2nd shot I remember using the 1 MOA tick mark and adding that for elevation. I think the 3rd shot was back to no hold over. I was not being very methodical about shooting that day I guess, so it is likely I just went back to the cross hair to see what happened.

I might have an ES issue as well. I have am chasing a pressure spike now and have been going over everything the best I can. I have a case guage I am using and remeasuring all the brass and trying to determine if head space is an issue etc. So far all seems ok except the brass is on the max for length side of things. Trimming is in order and started that last night. Case neck thickness is almost identical to the new Lapau brass after 6 firings.

I did shoot the 160 matrix at 1280 the next day after chronoing and zero. I left the vid cam at home but the bullets flew very well.

 

[BrentM]

You will see left side strikes in this vid. As per discussion above 1 reason was due to zero being off to the left. Another being my lovely spotter telling me the 1st strike was right of target. If I am thinking I am shooting right I am going to naturally adjust left. LOL Newbies!!!!



[ame=http://www.youtube.com/watch?v=4ph6CahBtCo]1470 and 1500 yards w 6.5 - 284 - YouTube[/ame]

 

[WildRose]

With such a consistent error my suggestion would be to move out to either 200 or 300 yds to get your windage zero and go from there staying with the same calculations for drop, spin drift etc.

I've always found that if my rifles are zeroed at 100yds and I have "windage issues" at long range that's a problem usually easily solved by moving out to 200-300yds to get my zero windage set.

When you get beyond 600yds the tiniest errors in set up or zero start to increase pretty much geometrically.

As a general rule of thumb we were taught that every time you double your range you square your errors. It's a pretty good general rule of thumb.

 

[BrentM]

Good info and thanks. I was wondering if there is an opinion about elevation from the 960 to the 1500. Do you all agree the drop is still off by the same amount at 960 and 1310? I know this is one of the problems with NOT shooting at steel or an actual target. I just don't time right now to spend a day just shooting for drop. I figure if am under 1 MOA right now ON TARGET, I am good to go for a wolf. : )

 

[Broz]

I know this is one of the problems with NOT shooting at steel or an actual target. I just don't time right now to spend a day just shooting for drop. I figure if am under 1 MOA right now ON TARGET, I am good to go for a wolf. : )

BINGO! But with all the angles you can in no way tell what 1 moa is from a miss that lands on an angled surface from a bullet coming in at a huge angle. We want to think the bullet is arriving from a line to us. But we know it is coming in from above. Especially a 6.5 at these distances.

If at all possible I would look for a rock wall to shoot at. Or at least a very large rock with a vertical face. Pic an aim point on the face like a crack, moss, white spot etc. Then you can use your moa reticle to measure the error between aim point and impact. Not nearly as good as paper or steel, but better than a target on an angle.

Jeff

 

[BrentM]

Ok, perfect. I am taking the boys hunting this weekend and will see if I can find a suitable target that I can get to. I will change my approach to this issue as suggested and work on a more scientific solution. Thanks for all the feed back.