Zeroing issue

[GlennUK]

Glenn,
It’s good that you are aware of the effect that shooting at an upward or downward angle can have (in principle) but in your case - as you have described your range setup - the angle was only 4 degrees (i.e. 6.5m elevation difference over 100m). The difference between the true horizontal distance the bullet travelled & the distance it travelled on the hypotenuse in your case is only 210mm (approx). You don’t need to compensate for a bullet travelling 210mm less over 100m (or 210mm further depending on how you measured your range). So I’m curious as to how you were “compensating” for anything?

The question isn’t an implied criticism - it’s only a means of understanding exactly what you were doing as you may have been inducing wider than necessary shots on the target due to trying to compensate for something unnecessarily as “compensation” implies you were adjusting point of aim or sights.

The effect of gravity on the flightpath of the bullet is proportional to the angle deviation from the horizontal.

Shooting horizontally the effect of gravity on the bullet is 100% down. When shooting at an angle the effect of gravity is reduced on the bullet (whether shooting up or down) and the reduction is proportional to the angle. In this case it equates to a v.small adjustment compared with the rifle having been zeroed on the flat. It doesn't affect grouping, only trying to hit a specific point.

 

[paul o']

Just a 2p the B14 rail comes lose its a know !
Your three shot group was it home rolled or factory !
If your aim was at the same point even with a wonky scope a CM should be shooting far better than that is
Iam not taking the **** on anything it's just how I see it . What part of Essex are you mty.

 

[webley701]

The effect of gravity on the flightpath of the bullet is proportional to the angle deviation from the horizontal.

Shooting horizontally the effect of gravity on the bullet is 100% down. When shooting at an angle the effect of gravity is reduced on the bullet (whether shooting up or down) and the reduction is proportional to the angle. In this case it equates to a v.small adjustment compared with the rifle having been zeroed on the flat. It doesn't affect grouping, only trying to hit a specific point.

Your exercise in geometry confirms the figures I had already given you.

The difference between the true horizontal measurement (which is what is used to calculate ‘drop’) & the measurement along the hypotenuse (line of fire) is only 210mm i.e. a distance of 100.0m compared to 100.21m. This is so slight as to be meaningless as regards difference in point of impact. You appear to be trying to compensate for a difference in drop over approx 4 inches of extra (or less) flight.

Even at (say) 300 yards the angle would have to be several times greater than yours was in order to have a noticeable effect on point of impact.
At rather extreme angles the difference in height between the bore line & the sight line can also affect point of impact but here once again your angle of just 4 degrees (fractionally less actually) makes the consideration totally irrelevant.

It could be worth you contemplating what effect on your overall group size trying to compensate for something which effectively didn’t exist may have had.

 

[GlennUK]

Your exercise in geometry confirms the figures I had already given you.

The difference between the true horizontal measurement (which is what is used to calculate ‘drop’) & the measurement along the hypotenuse (line of fire) is only 210mm i.e. a distance of 100.0m compared to 100.21m. This is so slight as to be meaningless as regards difference in point of impact. You appear to be trying to compensate for a difference in drop over approx. 4 inches of extra (or less) flight.

Even at (say) 300 yards the angle would have to be several times greater than yours was in order to have a noticeable effect on point of impact.
At rather extreme angles the difference in height between the bore line & the sight line can also affect point of impact but here once again your angle of just 4 degrees (fractionally less actually) makes the consideration totally irrelevant.

It could be worth you contemplating what effect on your overall group size trying to compensate for something which effectively didn’t exist may have had.

Thanks i did say it was a v.small difference.

Unsure why aiming at a specific point i.e. zeroing a rifle, would have on grouping as opposed to not aiming at a specific point.

 

[VSS]

Unsure why aiming at a specific point i.e. zeroing a rifle, would have on grouping as opposed to not aiming at a specific point.

Because if you're not careful you find yourself chasing shots, which seems to be what you did. Aiming off to compensate for where the previous shot landed.
What you should be doing is aiming at a specific point, and keep aiming at that specific point, for every shot, regardless of where the shots land relative to your aiming point.

 

[GlennUK]

Just a 2p the B14 rail comes lose its a know !
Your three shot group was it home rolled or factory !
If your aim was at the same point even with a wonky scope a CM should be shooting far better than that is
Iam not taking the **** on anything it's just how I see it . What part of Essex are you mty.

Thanks, i know that the rail came with some 'lock tight', ill speak with ISS who refitted it for me when i had issues, check whether they used it.

Factory ammo

I don think its the rifle, i am a novice shot with a rifle, this was the final three shot string of a dozen rounds fired that day.

The previous shots were somewhat off as I adjusted my shooting position/mounting.

I hope to improve in my shooting somewhat with practice.

Im in Brewntood, where are you form?

 

[GlennUK]

Because if you're not careful you find yourself chasing shots, which seems to be what you did. Aiming off to compensate for where the previous shot landed.
What you should be doing is aiming at a specific point, and keep aiming at that specific point, for every shot, regardless of where the shots land relative to your aiming point.

I take your point, was aiming at the same spot, despite what the target looks like! I was aiming at the tip of the diamond.

 

[VSS]

I take your point, was aiming at the same spot, despite what the target looks like! I was aiming at the tip of the diamond.

In that case sorry, I've misread some of your earlier posts. I got the impression that you were trying to aim off to compensate.

(If it's any consolation, I would be absolutely delighted if I could achieve a group like yours, yet I shoot plenty of deer. I freely acknowledge that I'm a crap shot at targets. I probably overthink it and try too hard. Maybe you're doing the same?)

 

[paul o']

Thanks, i know that the rail came with some 'lock tight', ill speak with ISS who refitted it for me when i had issues, check whether they used it.

Factory ammo

I don think its the rifle, i am a novice shot with a rifle, this was the final three shot string of a dozen rounds fired that day.

The previous shots were somewhat off as I adjusted my shooting position/mounting.

I hope to improve in my shooting somewhat with practice.

Im in Brewntood, where are you form?

Southend mty and i am happy to help with your zeroing

 

[GlennUK]

Southend mty and i am happy to help with your zeroing

Thanks, appreciated. Ill let you know if i have further issues.

I have lived in Southend several times last time was Victoria Rd 100m form the seafront in what became 'Thorpe Bay' apparently!!!

I always thought i moved to Southchurch but shortly after the council put sings up along the seafront between Victoria rd and the Kursaal saying Thorpe bay, caused a stink IIRC with the residents of Thorpe bay 'proper'.

 

[paul o']

Iam in southchurch lol lived in vic Rd 40yrs ago

 

[ofbiro]

If I understand well, there are two different problems:
1. Adjusting the mounts to the scope
2. Shooting with an incline (uphill or downhill).

Solutions to problem Nr.1, both suggested by a couple of gunsmiths:
- reaming the mount rings with a suitable reamer, i.e. with the exact diameter (1", or 25 mm or 30 mm); the reamers are sold by Brownell, but they are a bit expensive for the common rifleman/stalker;
-tightening a bit, not too much neither loose the ring screws, then hammering the mounts with a plastic or rubber hammer; tighten a bit the screws and repeat the operation.
When shooting uphill or downhill the Earth attraction, a.k.a. gravity is always the same as with horizontal barrel, BUT the trajectory in both cases is closer to the barrel axe (i.e. the imaginary straight line in the center of the barrel. The fact is similar to the behavior of a very rigid fishing rod. The distance from the hook to the top of the rod is always the same, whatever is the inclination of the rod, BUT (very capital letters) the distance from the hook to the rod decreases with the rod inclination, whatever it is upward or downward.

 

[webley701]

Thanks i did say it was a v.small difference.

Unsure why aiming at a specific point i.e. zeroing a rifle, would have on grouping as opposed to not aiming at a specific point.

The difference in drop of during a bullet travel of 210mm (4” approx) at 100m is around 0.001”.

It beggars belief that anyone would deliberately try to ‘compensate’ for such a minuscule amount by adjusting their point of aim. A reasonable inference then was that you expected the required compensation to be far greater. If that was so - given that no adjustment in point of aim was actually needed the ‘compensation’ you gave would then itself become an error (i.e. give an unexpected point of impact) - an error which you may have chased on the target, resulting in the rather large group. Hence my original question (which you hadn’t addressed) relating to how you were ‘compensating’ for something that practically doesn’t exist?

 

[GlennUK]

Iam in southchurch lol lived in vic Rd 40yrs ago

we were probably neighbours then!!! I lived there form around 84-88 ish

 

[GlennUK]

The difference in drop of during a bullet travel of 210mm (4” approx) at 100m is around 0.001”.

It beggars belief that anyone would deliberately try to ‘compensate’ for such a minuscule amount by adjusting their point of aim. A reasonable inference then was that you expected the required compensation to be far greater. If that was so - given that no adjustment in point of aim was actually needed the ‘compensation’ you gave would then itself become an error (i.e. give an unexpected point of impact) - an error which you may have chased on the target, resulting in the rather large group. Hence my original question (which you hadn’t addressed) relating to how you were ‘compensating’ for something that practically doesn’t exist?

Thanks for your 'help' so far.

I was aiming at the same point all the time, the size of the group is probably due to my lack of skill and unfamiliarity with the rifle.

No one was chasing anything, i was aiming at the same point all the time, so whether i was compensating incorrectly or not, i was aiming at the same point.

I am unsure how else to describe pointing the rifle at the same spot on the target.

 

[GlennUK]

In that case sorry, I've misread some of your earlier posts. I got the impression that you were trying to aim off to compensate.

(If it's any consolation, I would be absolutely delighted if I could achieve a group like yours, yet I shoot plenty of deer. I freely acknowledge that I'm a crap shot at targets. I probably overthink it and try too hard. Maybe you're doing the same?)

I hadn't shot from that position before, its in fact a 2nd floor Velux 'balcony' roof light. Ill take a picture next time i'm set up.

The balcony rail is too high to shot over comfortably so i made myself a shooting table top, that sits on the balcony rail, and use a step stool to be at the right height to mount the rifle.

With the angle i am shooting downwards getting a solid position was awkward, so i compensated by using a pad under the butt of the rifle. When i have shot on the flat i have used my left hand/fist.

Took me a few shots to find the right position as well as adjusting the height of the comb to ensure good sight picture every time.

 

[NP435]

I hadn't shot from that position before, its in fact a 2nd floor Velux 'balcony' roof light. Ill take a picture next time i'm set up.

The balcony rail is too high to shot over comfortably so i made myself a shooting table top, that sits on the balcony rail, and use a step stool to be at the right height to mount the rifle.

With the angle i am shooting downwards getting a solid position was awkward, so i compensated by using a pad under the butt of the rifle. When i have shot on the flat i have used my left hand/fist.

Took me a few shots to find the right position as well as adjusting the height of the comb to ensure good sight picture every time.

I would either make a bench or buy one that is stable for any zero work, sticks are not the tool for the job. Practice at 50 yards with the 22 until you group consistently that will teach you volumes. Establish a good natural point of aim and do not move between shots other than to load and fire ( meaning the support hands and arms remain in place) good luck.

 

[paul o']

There some serious overthinking going on pmsl
We will get into trigonometry and coriolis temp shift at 300 yrds soon and weather the shot was taken north south or east west or leaning to the left while holding off to the right ! God forbid canting while compression is held with the trigger finger .
just bore sight it stick out a target bag it on a bench rest it zero repeat and then move to sticks etc.

 

[Tim.243]

There some serious overthinking going on pmsl
We will get into trigonometry and coriolis temp shift at 300 yrds soon and weather the shot was taken north south or east west or leaning to the left while holding off to the right ! God forbid canting while compression is held with the trigger finger .
just bore sight it stick out a target bag it on a bench rest it zero repeat and then move to sticks etc.

Quite Paul, God knows what would happen should something big step out looking like it is going to bounce off any second!
Slide rules, counting beads, Apps, Casio's overheating!! won't help.
"put the crosshairs on it and pull the trigger" @GlennUK

 

[GlennUK]

Quite Paul, God knows what would happen should something big step out looking like it is going to bounce off any second!
Slide rules, counting beads, Apps, Casio's overheating!! won't help.
"put the crosshairs on it and pull the trigger" @GlennUK

I agree, but on a serious note, it is part of the learning process, to understand what is, and what is not important.

I learned a lot form those 12 rounds or so, having not had a chance to shoot the rifle much at all, not shot from that location and the adjustments I needed to make to get a solid position, etc.

The next time i shoot i will be much better prepared having learned what i did, having a) being new CF rifles, and b) having shot on the level.