Thread: What could cause this?

Originally Posted by gimp

Sample size, both when zeroing and shooting

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 ?

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,

A diamond also works well 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?

Originally Posted by Oldbloke

Could it be parallex related?

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....

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.

@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!

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!

@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.

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

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/