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.223 accuracy error

badtoro

Missed a fox last night around 200 yards, thought I rushed the shot. Federal premium 40 grain ballistic tip. Good quality scope, proven rifle.

Checked just now and on average it's about 0.75 of an inch left at 100 yards on 1 inch black dots. Corrected this.

Yet 3 inches left on fox silhouette at 200.

Set parralax for 100, didn't change it for 200.

Used support under rifle butt.

It's the consistency of the error at 200 that I can't fathom.

It is breezy, this would shift POI to the left, but 3 inches?

Besides foxes, what am I missing?

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Cass

Have you checked parallax?

I don't mean clarity or turning the turret on the scope to 100, 200, etc. but actual parallax.

The crosshairs of the scope should not move when you move your head, with the rifle clamped. If it does then parallax is not set correctly. This movement means every time you shoulder the rifle the crosshair "floats" and you get a different POA (Point of Aim). As people tend you shoulder a gun the same each time it will/can account for the difference, but consistency.

If your parallax is off then any deviation from your "zeroing position" will result in a shift in POI as the crosshairs will "move" with your head/eye movement.

In a scope with a properly set parallax no matter your eye/head position the crosshairs will remain fixed.

The simple check for parallax is to set the rifle up in a locked/fixed position where it is almost clamped. Do NOT touch the rifle or as little as possible and look down the scope. It doesn't matter if your head is not in its natural shooting position, you're only checking for movement. Move your head slightly and if the crosshairs move with your movement then there is a parallax issue.

Parallax can be adjusted or eliminated by adjusting the eye relief and focus as necessary to the point where you have clear sight picture, target picture and no movement of the crosshairs. It can be easy or it can take a little time to get exactly right, but the difference will be immediately noticeable with more consistent groupings, no loss/shift of zero, and if the rifle and ammo are good a reduction (won't say elimination) of flyers.

cookimonster

Cass,

Could you explain what you mean by moving cross hairs:

Move your head slightly and if the crosshairs move with your movement then there is a parallax issue.

I'm confused, if cross hairs are fixed, surely moving your eye will give the impression of the cross hairs jumping off the point of aim?.

badtoro,

Just ran some figures through Strelok+ for my 270 and 30-06
Now this is just paper balistics but, at 100 yards with a 5 mph full value wind the deviation is 0 at 100 yards but quickly jumps to 2 inchs at 200 yards. So again just paper and not actual shots on but something to think about.

Cass

cookimonster wrote: »

Cass,

Could you explain what you mean by moving cross hairs:

Move your head slightly and if the crosshairs move with your movement then there is a parallax issue.

I'm confused, if cross hairs are fixed, surely moving your eye will give the impression of the cross hairs jumping off the point of aim?.

The crosshairs never actually move, which i thought was obvious, its only the impression that they do.

It's like looking at the eyes of a painting and they seem to follow you. You know full well the painted eyes cannot move but it's looks as if they are.

If you have your rifle clamped so it does not move and you make no contact with it (not vital, but i prefer to eliminate any movement of the scope by touching the rifle), look down the scope to the target. Now slowly move your head, not eye, but your head while looking at the target. If the crosshair "moves" with the movement of your head, or to be exact so there is no confusion, gives the appearance of moving then your parallax is not set.

If the parallax on a scope is correctly set then when you move you head your crosshairs will remain on the same POA you set it at when clamping the rifle. If the crosshairs can "move" with your head movement due to improperly set parallax then the crosshair will give a, suppose you'd call it, false POA.

The picture below shows what happens when you move your head and the crosshairs "move" with you. IOW improperly set parallax. Originally the crosshairs were on the target. As the shooter moves their head up and slightly to the right, the crosshairs move down, and slightly left. This is a parallax issue.

6034073

Cass

badtoro wrote: »

It is breezy, this would shift POI to the left, but 3 inches?

Yes. Should take my own advice and when i hear hoof beats think horses, not Zebra.

A quick reference guide:

Description | Speed | Effects |
Calm | Calm | Calm wind. Smoke rises vertically with little if any drift.
Light Air | 1-3 mph | Direction of wind shown by smoke drift, not by wind vanes. Little if any movement with flags. Wind barely moves tree leaves.
Light Breeze | 4-7 mph |Wind felt on face. Leaves rustle and small twigs move. Ordinary wind vanes move.
Gentle Breeze | 8-12 mph | Leaves and small twigs in constant motion. Wind blows up dry leaves from the ground.
Moderate Breeze | 13-18 mph | Wind moves small branches. Wind raises dust and loose paper from the ground and drives them along.

Now in a 5 mph full value breeze a 40gr 223 will drift 2.3 inches at 200 yards with a 100 yard zero.

In a 10mph breeze the same round will drift over 4 inches at 200 yards with a 100 yard zero.

Even if you don't get full value winds you can see how much the 40gr stuff will drift in a breeze that you hardly feel. It's not much better for 55gr stuff. Shooting the other day and i had 1 inch of right drift in a 2/3 value wind at 100 yards. Speeds were about 11-12mph.

cookimonster

Thanks Cass

pm.

Lots of great info from Cass. I just got my.223 last year and after a lot of time at the range I now have the rifle set at 200 yards.

Sent at this distance you will be about an inch high at 100 yards and just over an inch under at 300. I find the.223 a fairly flat shooting range not as flat as a swift mind you but flat enough to set at 200 yards and be confident to shoot between 100 and 300 with ease

Hope this helps

badtoro

Ok, thanks for the responses.

I think before I do anything else I'll shoot again on a calmer day, just to rule that out as yesterday it may well have been the wind.

On parallax, yes I did as Cass says above, although not clamped it was on bipod with a cap under the butt and without touching at all I was checking for scope movement against a white target.

Though I will check again minus the cap incase that had any negative imput.

I might be over thinking it and seeing a problem that ain't there.

badtoro

Looks likely to have been simple wind drift from the below ðŸ™„

https://www.federalpremium.com/products/rifle/premium-varmint--predator/vshok-nosler-ballistic-tip/p223p

Mississippi.

Thanks for that info Cass.
Will just double check that on my own.