Leveling the Scope Reticle for Long Range Rifles

[bruce_ventura]

Doc,

That's really like comparing apples and oranges, because a good boresight collimator has many uses. I own a laser boresighter and always use a collimator instead. Part of the problem is that the bore attachments for the laser boresighters that fit in the muzzle are are poorly constructed. The laser is usually far from parallel to the bore.

The lasers that fit in the chamber have similar issues. At best, they tell you the direction the chamber is pointed, whereas you want to know the direction the bore at the muzzle is pointed. Similarly, lasers that attach to the muzzle crown indicate the direction the crown is pointed.

The boresight collimator can be used anywhere and takes about a minute to install. Lasers are difficult to use in tight quarters, like the garage, shop or inside the house. A long distance, usually 25 feet or more, is need to see the laser spot through the scope. And it takes a while to set lasers up: a reflective target is usually needed to see the laser in bright daylight.

Most shooters think of lasers and collimators as devices for zeroing optical sights. A collimator is a general purpose instrument that allows reproducible measurements of boresight misalignment. When I install a scope on a rifle, I use the collimator several times during the process to check boresight alignment of the rings. Finally, I use it to set the optical zero. However, barrel vibration will usually cause a sporter weight barrel to throw shots several inches away from the bore direction. A boresight collimator is often no more accurate for zeroing than looking down the bore.

 

[DocB]

Dr. Winker,

Thank you very much for your indepth answer. Very much appreciated!

Doc

 

[kermodie]

If the elevated POI falls to the right of center, rotate the scope right. When the scope is then re-aimed at the "plumb" target line the muzzle will naturally follow - in this case, moves to the left.

Just picture the scope mounted 45 deg from bore center. If you rotate it farther left the point of impact will fall farther right. The reticle is always plumb when looking at the target, it's only the bore CL (POI) that changes.

 

[kermodie]

Sorry guys, I believe I have it figured out now.
Thanks rick523 for the info

 

[walkin]

You have me scratchin my head, would you care to share ,Thanks

 

[ItchyTF]

I purchased the Wheeler Level Level Level's a couple of years ago and have used them to readjust the scope's on all my rifles....would these level's be applicable to the technical aspects of this thread... ???

 

[bruce_ventura]

I'm not sure how to answer that question. The Wheeler levels are a variation of method 5. They work fine for short range.

 

[ItchyTF]

Would 300 yds be considered short range ???

 

[bruce_ventura]

On this site, yes.

 

[ItchyTF]

Thanks for your reply..... gun)

 

[CanardNoir]

Having sought long-range accuracy since the mid-1960s, it seemed like hit-or-miss mechanics dominated my ability as long as I used the conventional bases and rings of the day.

Granted, I achieved some excellence results early on with the then-new 6.5mm Rem Mag despite its shorter barrel and light weight. Under half-inch groups became the norm with that rifle, but I was unable to duplicate that consistency as I built on larger caliber rifles including Brownings early (1990s) M-1000 with thumbhole stock, heavy barrel and BOSS.

No combination of hand loads, higher-priced scopes, or radical bench-rest oriented stocks seemed to make a real difference, until the early 2000s when I bought a new bottom-of-the line Savage .17 HMR for truck carry around the farm.

Determined not to put a $300 scope on a $100 rifle, I bought a cheap 3X9 TASCO scope and a decent pair of $20 groove-mounting rings which easily mounted to the top of the rifle's grooved receiver (which I cleaned up both mounts and receiver grooves a bit with a fine 3-cornered file). I used a bore laser to quickly align the scope cross-hairs at about 10 yards. Then tightened it all in place.

Using a modified version of the 1-5-5-5-shot barrel break-in, I took no special care in shooting into the dirt in the backyard or cleaning the .17 cal. barrel. I didn't expect much so I had a built-in excuse if it didn't group.

But the cheap build shot 1/2-inch groups at 50 yards and got progressively better as I shot and cleaned the barrel!

In my estimation, the weak link of my previous builds was the scope mounting system - because there are/were too many mechanical connections incorporated into mounting bases and rings. And all of my old dove-tail windage-adjusted mounts have now been replaced.

I've long since incorporated the Wheeler leveling system for both the action and the scope, but still rely on the bore laser to proof the final alignment.

On a Rem 700 action, I recent built up a 7mm STW using a DNZ (one-piece scope mount) and admittedly was much more careful than I hand been with the .17 HMR project. But the bore laser was dead-on the vertical cross-hair at 20 yards and the first 10 shots started printing 2-inches high at 100 yards, and grouped inside 0.715" with the last three shots of 140 gr. Remington factory ammo.

Granted, I may not be able to better that performance with hand loads and Berger bullets - but considering time, effort, and total investment, the proper mounts, alignment & leveling of the scope has already helped in building the same level of confidence I had with the 6.5mm Rem Mag. And the 7mm STW remains a very promising work-in-progress.

And generally speaking, money can't buy that kind of confidence afield.

 

[CanardNoir]

Would 300 yds be considered short range ???

I'd call it the outer limit of short range.

Anything over about 350 yards remains a difficult shot for most of the rifle shooters I have known.

A friend in South Dakota built a .243 Win with a all of the really long-range bells & whistles you could want on a shoulder rifle. And he has long since quit taking shots under 500 yards.

One afternoon on his family's ranch, with his ballistic calculations and no wind, I consistently hit a 10"-dia. steel plate at a half mile.

And to me, that was really long range!

 

[shortpants]

Question??? Do you recommend shooting a plumbline test after using the alignment tool you sell to verify results? It seems the plumbline is the most accurate way to eliminate errors so why not just skip the alignment tool and shoot the plumbline to begin with? 6 or even 12 rounds is still cheaper than the alignment tool in most cases. The exception would be if you have more than a few scopes to worry about. Am I on the right track or did I miss something? No disrespect meant towards the alignment tool just wondering if its worth buying for someone like myself who only owns a couple of scoped rifles? Guess I need more rifles!!!

 

[CanardNoir]

If you believe that the last four-inches of the rifle barrel are the most important, the mechanical relevance of the so-called "plumb line" would depend upon the end of the barrel squaring with the mounting of the scope base on the action.

The article as I understood it advanced the theory that there was no true centerline to any given barrel (all barrels have some degree of curvature) - so reducing that variable in making the true vertical plumb & true horizontal plumb converge - controls accuracy down range.

Because the barrel is threaded into the action, each degree of tightening would change the concentricity of the centerline's point of impact. Using cryogenics could help, but not alleviate that true-alignment problem - making everything square.

Granted, modern machining equipment can reduce the misalignment tolerance of the receiver & scope mount - but remaining are the concentricity of the scope rings, and the barrel curvature (however small) may still matter as you stretch your rifle's range. And helps justify that ballistics app on your iPhone!

This was my thinking in reducing the number of mechanical joints between the scope and the action to improve accuracy.

Even when you try to reduce the effect induced by the coefficient of thermal expansion by using similar metal mounts (rather than high-grade, even T-6 aluminum) - your accuracy can still go out the window if you don't maintain vertical alignment when you squeeze off that 500 yard shot.