What could cause this?

Hey team,

Shot two rifles yesterday.

Tikka T3 308 18” - Leupold vx5 - talley rings - Hardy can
Shooting Superformance 150sst

REM 700 CDL 7mm-08 18” - Leupold vx3 - talley rings - DPT can
Shooting REM corelokt 140gr

Both rifles were zeroed at 100y and were shooting sub MOA (REM slightly tighter)
The question I have is at 300y…

Conditions:
18C, 1023 pressure, 49% hum,
Wind: about as calm as you can hope for. Small puffs of breeze intermittently.
If there was a puff, at the shooter it was from 180 degrees. At the target it would puff either left or right. Very light though.

At the 300y, the 308: elevation good,but ~3.75inches to the right
7mm 08: elevation good. But ~3.5 inches to left. *I did a third shot but it was a flyer and I knew it would be (same height but out to the left quite a bit)
Both groups were still MOA


Could the small puffs of wind have this effect? Or Is it more likely my shooting position,
I tried to keep it as consistent as possible. Or is it something else.

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Doesnt take much breeze to move them at 300yds left or right.I use a bit of light ribben hanging off a electric fence stay.I dont pull the trigger till ribben drops,hangs plum then squezze off the trigger.
Allow for your error squeezing off the trigger too and getting your breathing right.

Random dispersion.. velocity differences in factory ammo from shot to shot. Either way, at 300yards that not a group to be ashamed of, especially with factory ammo

Its a dead deer,left or right.:thumbsup:

Thanks! I thought about that today. Will do that in future.
So you wouldn’t worry about changing cross hair left or right based on that?

I guess more time at the range will answer a lot of my questions.

For what it’s worth,
I didn’t have a chrno, plugged all ambient figures I could get from met service, elevation from topo.
And took away 25fps for every inch of barrel chop. Based on a 24 inch starting barrel and box velocities.
I was pretty happy.
Based on the data I dropped my speed a little for each. ~25fps for each rifle. Can anyone say if that was a mistake? I didn’t verify that change :XD: because I was sick of walking and needed to get home

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Originally Posted by Jus

Random dispersion.. velocity differences in factory ammo from shot to shot. Either way, at 300yards that not a group to be ashamed of, especially with factory ammo

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Thanks mate.

Also, I used spirit level on target and on the barrel when it was on the target to ensure There was no shooting angle

call it good...deer is deader than a dead thing....

Wouldn't hurt to check your scopes are mounted so the horizontal crosshairs are dead level relative to the bore. Being out a little can cause shots to land a bit to the side of vertical on target ( it bears on how the rifle is held whilst shot ). Usually it would show up more with highly accurate ammo as opposed to factory ammo. I don't think the breeze as you described it would cause that much drift of your shots although undoubtedly it can if strong enough.
Only if this really matters though. As others say with that accuracy you're good to go and kill stuff.

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Originally Posted by 30.06king

Wouldn't hurt to check your scopes are mounted so the horizontal crosshairs are dead level relative to the bore. Being out a little can cause shots to land a bit to the side of vertical on target ( it bears on how the rifle is held whilst shot ). Usually it would show up more with highly accurate ammo as opposed to factory ammo. I don't think the breeze as you described it would cause that much drift of your shots although undoubtedly it can if strong enough.
Only if this really matters though. As others say with that accuracy you're good to go and kill stuff.

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Thanks mate, appreciate that. This is the method I used: I checked a shops work with this method against. Gunsmiths work and and I thought the shop job was out slightly but gunsmiths was good. I could be wrong though.

Pointed the rifle away from a concrete wall in the garage. End of stock butt was about 3m away from the wall. Ensured the rifle was level with a high quality spirit level. Hung a plumb Bob from the ceiling so it was just sitting off said wall and in line with rifle.
Next I turned the lights off grabbed a strong little torch and pointed it down the muzzle end of the scope. Cross hairs lit up on the wall and adjusted the scope and rifle till it was spotty dick with the plum Bob.

Not sure if I read that method on here but I feel it works.
Thoughts?
*Had to turn the magnification up or down for the cross hairs to become sharp on the wal.

were your targets at an angle to you??? just that the holes look to be going in left to right..if it was indeed less than square your error sideways is LESS than ruler measures.....

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Originally Posted by Micky Duck

were your targets at an angle to you??? just that the holes look to be going in left to right..if it was indeed less than square your error sideways is LESS than ruler measures.....

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Good spotting, I thought that too, but I did my best to get it perpendicular with the shooting line.
It was 10mm aqua line Gib…created a small puff of white when a shot hit which I was thankful for. Didn’t need to walk the 300y, not knowing if I’d hit anything. Especially without the chrono.

Could the twisting bullet hitting the GIB cause the bullet to travel. Like when you are hand drilling a piece of metal without a centre punch to start things off.

I doubt it, but GIB is pretty flex. And it was a large ish sheet. Also reason why I didn’t like walking extra.

Really appreciate the thoughts everyone, keep em coming if you like.

hmm that being able to see if hit thing sounds good.... good use for broken sheets of gib.

Sample size, both when zeroing and shooting

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Originally Posted by gimp

Sample size, both when zeroing and shooting

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Agreed

Greetings,
I suggest you repeat the test with a better aiming mark. A hollow square or circle that you can quarter with your cross hairs will work a lot better. Also consider zeroing at 200 metres.
Regards Grandpamac,

Was your Zero bang on to start with ?

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Originally Posted by grandpamac

Greetings,
I suggest you repeat the test with a better aiming mark. A hollow square or circle that you can quarter with your cross hairs will work a lot better. Also consider zeroing at 200 metres.
Regards Grandpamac,

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A diamond also works well :thumbsup: hold crossbars on points of diamond

or put your cross at 45 degrees for same reasons as previous two suggestions.

Both variations in the ammo and the shooter.

Could it be parallex related?

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Originally Posted by Oldbloke

Could it be parallex related?

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Good call.
If parallax not right it can cause all sorts of issues.
Have a look at todd hodnetts videos regarding parallax and the significance of bubble levels.

Sent from my SM-A226B using Tapatalk

typically vertical dispersion is inconsistency in how you control the recoil ie holding tightness inconsistency grip/or butt pressure ect
horizontal dispersion is grip and not lining up directly behind the rifle

thats pretty good shooting regardless so it could just be adjusting between rifles

if you want to get really serious about it get someone to film you shooting then you can really pick apart what you are doing

Well within 1 minute of deer , get out and shoot something for the pot

At 300m you do start to see minor wind effect the groups. Have a look at 'Applied Ballistics' and deliberately dial in a 10m/sec crosswind.
You'll see a couple of clicks to account for. 0.2milrads at 100m is 2cm, so that is 6cm drift at 300m (plus or minus one for height depending on direction).

Anything minor adds up too but if it were me i would leave the scope as is but really make sure that crosshair doesn't move independently to the target when you support the rifle / hands off / no cheek weld etc and bob your head slightly when looking through the scope. I do this every time (when you know you can risk taking the time). Bad parallax will definitely amplify any changes coming from your body position (that the terrain might be causing). Especially if your elbows aren't level....

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Originally Posted by JBNZ

Thanks mate, appreciate that. This is the method I used: I checked a shops work with this method against. Gunsmiths work and and I thought the shop job was out slightly but gunsmiths was good. I could be wrong though.

Pointed the rifle away from a concrete wall in the garage. End of stock butt was about 3m away from the wall. Ensured the rifle was level with a high quality spirit level. Hung a plumb Bob from the ceiling so it was just sitting off said wall and in line with rifle.
Next I turned the lights off grabbed a strong little torch and pointed it down the muzzle end of the scope. Cross hairs lit up on the wall and adjusted the scope and rifle till it was spotty dick with the plum Bob.

Not sure if I read that method on here but I feel it works.
Thoughts?
*Had to turn the magnification up or down for the cross hairs to become sharp on the wal.

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@JBNZ I've learnt something new from this blog today, thanks. Getting my scopes dead plumb is something I really struggling with. I'm going to try "The Concrete Wall Method," which I had never heard of.... I also struggle with getting the rifle plumb in the vice (plywood packers), what part of the rifle do you put the spirit level on especially if the receiver is round with no flat surfaces? Is the iron rear sight (removed) dovetail accurately level? Alternatively, is the din rail accurately level? I know a couple of my scopes are not perfectly setup and it is irritating!

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Originally Posted by Hugh Shields

@JBNZ I've learnt something new from this blog today, thanks. Getting my scopes dead plumb is something I really struggling with. I'm going to try "The Concrete Wall Method," which I had never heard of.... I also struggle with getting the rifle plumb in the vice (plywood packers), what part of the rifle do you put the spirit level on especially if the receiver is round with no flat surfaces? Is the iron rear sight (removed) dovetail accurately level? Alternatively, is the din rail accurately level? I know a couple of my scopes are not perfectly setup and it is irritating!

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@hugh

In the absence of a flat top reciever, if you attach the bottom half of the rings, that gives you a good level surface to use to get the rifle level. If not you have other problems. If the rings you are using have a verticle split like warnes etc, you can fit one flat ring from spare parts collection and then remove it once the rifle is level and cinched in place as per below. Then fit the rings you will use.

To hold the rifle I put a rifle rest in an engineers vice, and then use a small tie down strop to hold the rifle tight in the rest. It takes a few goes sometimes to get it sitting right and level, but once the strop is tight it works well. No risk of crushing any part of the rifle in the vice.

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Originally Posted by Bill999

typically vertical dispersion is inconsistency in how you control the recoil ie holding tightness inconsistency grip/or butt pressure ect
horizontal dispersion is grip and not lining up directly behind the rifle

thats pretty good shooting regardless so it could just be adjusting between rifles

if you want to get really serious about it get someone to film you shooting then you can really pick apart what you are doing

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Was going to suggest this - it's real hard to critique someone's targets like this when there could be a LOT of different factors at play... In all honesty it's almost no point in looking at the targets and offering up ideas without seeing the shooting end of things. The 'group diagnosis' diagrams are good but assume that all factors at the firing point are correct and controlled, and most of the issues are human factor not at the target end!

Relevant information here.
https://www.nzhuntingandshooting.co....e-level-61019/

@Hugh Shields Let us know how it goes for you.
I can’t really help with getting a rifle level without a flat top receiver.

I never used a vice. Just a bipod and backers under the feet in order to get it level.

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