Cant errors

[DD789]

one question with Scott's technique for adjusting cant error. is the 10 and 25yrd. distance measured from the muzzle, breech or front bell of the scope? I'm thinking from the muzzle.

Choose one and stick with it. Doesn't really matter as long as your sight dope is using that as the starting point. When you scope range find the front bell is what is being used to focus with so that is the starting point.

TimmyMac1

 Thanks that makes sense.

[Scotchmo]

one question with Scott's technique for adjusting cant error. is the 10 and 25yrd. distance measured from the muzzle, breech or front bell of the scope? I'm thinking from the muzzle.

It does not matter.

It doesn't have to be exactly 25 yards. Just try to be within a couple of yards of the trajectory apex. 30 yards might be better if you use a high scope.

It does not have to be 10 yards either. Just get as close as practical and still be safe. As the closer distances will require more holdover, it will exaggerate any scope cant errors.

The exact distance measurements are critical when calibrating for range estimating. But this is for cant errors, so exact distance measurements are not important.

[DD789]

one question with Scott's technique for adjusting cant error. is the 10 and 25yrd. distance measured from the muzzle, breech or front bell of the scope? I'm thinking from the muzzle.

It does not matter.

It doesn't have to be exactly 25 yards. Just try to be within a couple of yards of the trajectory apex. 30 yards might be better if you use a high scope.

It does not have to be 10 yards either. Just get as close as practical and still be safe. As the closer distances will require more holdover, it will exaggerate any scope cant errors.

The exact distance measurements are critical when calibrating for range estimating. But this is for cant errors, so exact distance measurements are not important.

Thanks Scott for the additional information. I guess I was over thinking about adjustments.

[William]

This is some really great info, I will be re-adjusting my scopes tomorrow for sure. I have a laser lever that will be perfect for the job! I often get times when my POI is on at close range and off at longer ranges, now I know how to correct the error using the proper adjustments and tools.

As for setting Distances as some have mentioned I do understand it doesn't matter as long as it is 10 +/- or 30 +/- a couple yards, I site in at 40 yards zero on my guns depending on the FPS or the weight pellet I am using. Anyway what I am really trying to say is I never measure my distance to the target from the muzzle, what good would that do (nothing) in my opinion I am not going to step in front of my muzzle every time I check a distance. After all, I do use a laser range finder at my eye not from the end of the muzzle. Besides 2 thirds of a yard isn't going to make a differnce anyway, unless you shooting past 2 or 300 yards at a low velocity!

My Skil Laser Level... I may have to wait until a cloudy day or just before sunset due to it my not show up in bright daylight. Works great indoors. I have woods where I shoot so maybe it will work ok in daylight!




Thanks for the info Scott  and everyone else as well 

William

[TimmyMac1]

This is some really great info, I will be re-adjusting my scopes tomorrow for sure. I have a laser lever that will be perfect for the job! I often get times when my POI is on at close range and off at longer ranges, now I know how to correct the error using the proper adjustments and tools.

As for setting Distances as some have mentioned I do understand it doesn't matter as long as it is 10 +/- or 30 +/- a couple yards, I site in at 40 yards zero on my guns depending on the FPS or the weight pellet I am using. Anyway what I am really trying to say is I never measure my distance to the target from the muzzle, what good would that do (nothing) in my opinion I am not going to step in front of my muzzle every time I check a distance. After all, I do use a laser range finder at my eye not from the end of the muzzle. Besides 2 thirds of a yard isn't going to make a differnce anyway, unless you shooting past 2 or 300 yards at a low velocity!

My Skil Laser Level... I may have to wait until a cloudy day or just before sunset due to it my not show up in bright daylight. Works great indoors. I have woods where I shoot so maybe it will work ok in daylight!




Thanks for the info Scott  and everyone else as well 

William

+- a few yards at 30 yds is next to no adjustment but +- at 10 yards is huge click value and you need to be within a 1/2 yard with focus distance or you could miss the tiny zones in FT. From 22-40 the adjustments are just a few clicks but when you get below 12 yards the click value per yard is major.

TimmyMac1

[William]

This is some really great info, I will be re-adjusting my scopes tomorrow for sure. I have a laser lever that will be perfect for the job! I often get times when my POI is on at close range and off at longer ranges, now I know how to correct the error using the proper adjustments and tools.

As for setting Distances as some have mentioned I do understand it doesn't matter as long as it is 10 +/- or 30 +/- a couple yards, I site in at 40 yards zero on my guns depending on the FPS or the weight pellet I am using. Anyway what I am really trying to say is I never measure my distance to the target from the muzzle, what good would that do (nothing) in my opinion I am not going to step in front of my muzzle every time I check a distance. After all, I do use a laser range finder at my eye not from the end of the muzzle. Besides 2 thirds of a yard isn't going to make a differnce anyway, unless you shooting past 2 or 300 yards at a low velocity!


Thanks for the info Scott  and everyone else as well 

William

+- a few yards at 30 yds is next to no adjustment but +- at 10 yards is huge click value and you need to be within a 1/2 yard with focus distance or you could miss the tiny zones in FT. From 22-40 the adjustments are just a few clicks but when you get below 12 yards the click value per yard is major.

TimmyMac1

Thanks Timmy,
You are correct thats for sure, I think my wording is a little off, I just meant that as long as I do the testing and adjustment for the cant is at those approx distances and use the same distance each time for the settings. Still dont think I am wording it right.

My scope is 1/8" click at 100 yrds so the clicks are even more major as far as the amount of clicks, they are a little more precise!

William

[woogie_man]

Great read!!

Though another question....I have had my scope leveled with the rifle, and everything is good.  But as soon as I start to snug down the rings the scope moves and throws everything off.  I am using some bkl double strap mounts on the rifle.  Just trying to figure if there is an easier way to avoid this or not.

[rsterne]

Normally with scope rings, if you tighten alternate sides, a small amount at a time, you can avoid that....

Bob

[silent_airman]

I read this stuff, and I am even more confused than ever. 

I sometimes think I am in the wrong hobby. This is not for a complete klutz like me. 

Maybe I should go back to iron sights. My QB-58 has decent irons and I like it that way.

How about red dot sights? Are they as complicated as scopes are to align?

[avator]

Good info indeed.... I have a mirror at home that is just sitting there taking space. I now have the perfect use for it.

Thanks a ton.

[hogie]

as always, you all make me think a bit more. NOW I have to get a steady-rest ----- $$$ --- and I will have something to do this winter. thanks for the info!

[rsterne]

Another helpful hint I just ran across.... If you center the windage adjustment optically (by counting clicks is close enough) BEFORE installing the scope and then do the mirror trick to align the vertical crosshair to the bore, when you do your final sighting in you will be close to the optical center of the scope, at least for windage.... This will maximize the vertical adjustment range of the scope and make sure that the centering spring that holds the reticle in place isn't near the end of it's adjustment....

Bob

[woogie_man]

Have read on a few different places to use shims or something else that is a uniform size. Place them under your turret body, most scopes are flat here, and tighten the rings.  If your base is flat, as well as the scope, you will have the scope perfectly level.  I took the scope off of my powder rifle to give it a try.....and sure enough it worked great.  I have a set of feeler gauges that I used for that scope, and a set of playing cards for my airgun.

Cheap and quick, and it seems to work.

[chiro972b]

Ok, I'm lost. Rotate scope in the mounts until all shots are on the vertical line??? How are my shots going to be on a vertical line if I am rotating the scope in the mounts???  As soon as I rotate my scope, won't the elevation I dialed into my scope to zero it cause the shots to go off the vertical line? I'm not sure the point here. If I am centered at 25 and then come to 10 and my first shot hits the vertical line, why would I start rotating the scope? Are you saying if, when I come to 10 yards, my shots don't hit the line, then start to rotate?

I suppose if my scope were perfectly optically centered and I was able to zero using adjustable mounts (not likely) then I could rotate my scope and have the shots stay on the vertical line.

What am I missing?

[Scotchmo]

Ok, I'm lost. Rotate scope in the mounts until all shots are on the vertical line??? How are my shots going to be on a vertical line if I am rotating the scope in the mounts???  As soon as I rotate my scope, won't the elevation I dialed into my scope to zero it cause the shots to go off the vertical line? I'm not sure the point here. If I am centered at 25 and then come to 10 and my first shot hits the vertical line, why would I start rotating the scope? Are you saying if, when I come to 10 yards, my shots don't hit the line, then start to rotate?

I suppose if my scope were perfectly optically centered and I was able to zero using adjustable mounts (not likely) then I could rotate my scope and have the shots stay on the vertical line.

What am I missing?

Rotate scope in the mounts until all shots are on the vertical line?
YES

How are my shots going to be on a vertical line if I am rotating the scope in the mounts?
You are rotating the scope into alignment.

As soon as I rotate my scope, won't the elevation I dialed into my scope to zero it cause the shots to go off the vertical line?
It might, in which case you should rezero your scope before you continue.

If I am centered at 25 and then come to 10 and my first shot hits the vertical line, why would I start rotating the scope?
In that case, you are good to go. Don't rotate the scope.

Are you saying if, when I come to 10 yards, my shots don't hit the line, then start to rotate?
YES

[DevilsLuck]

Crucial reading material! Bookmarked...

[mnbob]

Scott and other contributors;
This should be put into a lesson plan and be required reading. I spent a career in military and around arms all my adult life, thought I knew a few tricks. Best solution short of paying an expert (Scott ?), I have ever heard of. Now is a good time to pull rifles from the safe and spend some time on snowy cold days.  Thanks to all.

[DevilsLuck]

I've re read this thread a dozen times. And I'm still not sure I get it... But I've got four days off to figure it out. And when I do... I suspect it will take my shooting to the next level.

[Back_Roads]

 Simple trick I use is to line up the center of butt of the gun stock on a straight edge or piece of paper, then look down the front of the scope and line my vertical line on the scope with the straight edge of the paper , then evenly tighten the scope rings , watching the alignment stays true as i tighten  (+) . it gets things close some tweaking with the mentioned methods may still be needed  but rarely.

[cpt_sfc]

I agree. Over the years I have had people that I have tried to explain this to but to no avail most of the time. I really have a hard time relating this to people who want a laser to shoot with. I still have a few rifles that look, not straight when shouldered by an other person they say your scope is crooked , I stopped trying to explain it.