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Precision Scope Mounting: By, Charley Robertson

Long range rifle shooting is more popular than ever. This is evident by the growing number of products marketed specifically for long range shooting. Today every scope manufacture has a product line of long range scopes enabling the average rifleman to accomplish what only a few years ago could only be accomplished by a few very elite, highly trained individuals with equipment so expensive only a government agency could afford to posses it. These scopes, fitted with target knobs and ranging reticules can only be an asset to your rifle if they are properly mounted. Mounting a long range tactical scope sounds on the surface to be an easy enough task but in reality nothing can be further from the truth. Having built hundreds of custom rifles and mounted thousands of scopes. I did not give the job enough serious analytical attention until I started shooting long range tactical matches and building long range tactical rifles for some of the countries top shooters. While shooting at various matches, I noticed several inconsistencies among very talented shooters. A typical conversation between three competitors all shooting 308s at 800 yards might go as follows:

"Man there must be more wind out there than I can see. I held ¾ MIL right and I still hit left.

"No kidding? I only held ½ a MIL right. I hit, but it was almost too much."

"Really, I held right on and smacked them all right in the middle."

How can three talented shooters have such a wide range of results? I thought it was condition changes that occur from shooter to shooter that could not be seen. Or maybe its the way each scope is set up on the rifle. What if the scope is mounted on a rifle in such a way that the vertical cross hair is not in perfect plumb to the rifle? Or a problem even harder to detect, what if when turning the target knobs to dial in the correct amount of elevation, the center of the cross hairs moving up and down are not exactly perfectly plumb? How far off do things have to be before it matters? This concept of keeping everything perfectly straight is not new, I’ve been doing that for years. I vise up on a rifle and place a good Starrett bench level on the receiver rails and make sure the cross hairs follow a line I have drawn on my shop wall. I needed these questions answered, so on a no wind day (for New Mexico that is a 3 to 5 mph wind) I experimented. I had two rifles chambered for the new 6.5 Creedmoor. Our shop built both rifles and they were identical set ups both having their scopes mounted in the conventional manner. There was a minor difference between the two in that one had a Leupold Mark 4, 6.5x20 FFP with a TMR reticule and the other had a Leupold Mark 4, 8.5x25 FFP with a TMR reticule. Both rifles had a good 100 yard zero. Shooting at a 12"x10" steel plate at 755 yards with a 3 mph wind from 3 o’clock, using a center hold, The shot from the first rifle hit just off of the left edge exactly where it should have and the shot from the second rifle hit ¾ of a mil to the right. At the range, I loosened the rings and rotated the scope on the rifle that was shooting too far right, so minutely that it was almost imperceptible in fact I wasn’t sure I even rotated it. Shooting again at 755 yards the point of impact moved about ½ a MIL left just off of the right edge. With a 3 mph wind from 3 o’clock using a center hold, it should have been just off of the left edge. I rotated the scope again in the same direction, and it moved another ¾ MIL in the same direction. Now it is shooting too far left. The other rifle that I left alone did not change point of impact proving that conditions were consistent. Simple fact, scope mounting matters, a lot! My next question was how can I make sure I attain the "perfect scope mounting job". I can’t take every long rang rifle to the shooting range and mount and remount scopes until everything works right. I MUST have a reliable method to perfectly mount a scope in the shop and know without question that it will function 100% correctly in the field. I set fourth to design and implement a system that would do just that.

The new system must secure the barreled action with the scope mounted in such a way that the centerline of the scope and the centerline of the rifle’s bore are both exactly in the same vertical plain. Then, dial the elevation knob through it’s entire range while looking through the scope making sure the cross hair’s center never leaves a perfectly vertical plumb line. Rigidity is the key. It is absolutely imperative that operating the target turrets over and over again causes no detectable movement in the assembly. To make a long story short, we designed a carriage assembly very similar to that of a rail gun. That carriage rigidly holds the barreled action and scope perfectly plumb enabling the operator to simultaneously operate the elevation turret through its complete range and view its movement over the perfectly plumb line. I obtained a perfectly plumb vertical line using a laser level on my neighbors building 35 yards from the shop. This eventually evolved into a grid with MOA and MIL marks accurately drawn on it so that scopes could be evaluated as far as their true movements but that is another story.

Using the new system the scope on the problem rifle was rotated in the rings so that it accurately tracked on the laser line. Another trip to the range. I use a software program on a PDA called Field Firing Solutions from www.precisionworkbench.com . After verifying a 100 yard zero the target at 755 yards was engaged. With a 7 mph wind from 135 degrees my software called for and I dialed in, 17 ¾ MOA of elevation and a hold of .4 MIL right. I got a center hit with both rifles. This was a great success.





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Precision Scope Mounting: By, Charley Robertson

Long range rifle shooting is more popular than ever. This is evident by the growing number of products marketed specifically for long range shooting. Today every scope manufacture has a product line of long range scopes enabling the average rifleman to accomplish what only a few years ago could only be accomplished by a few very elite, highly trained individuals with equipment so expensive only a government agency could afford to posses it. These scopes, fitted with target knobs and ranging reticules can only be an asset to your rifle if they are properly mounted. Mounting a long range tactical scope sounds on the surface to be an easy enough task but in reality nothing can be further from the truth. Having built hundreds of custom rifles and mounted thousands of scopes. I did not give the job enough serious analytical attention until I started shooting long range tactical matches and building long range tactical rifles for some of the countries top shooters. While shooting at various matches, I noticed several inconsistencies among very talented shooters. A typical conversation between three competitors all shooting 308s at 800 yards might go as follows:

"Man there must be more wind out there than I can see. I held ¾ MIL right and I still hit left.

"No kidding? I only held ½ a MIL right. I hit, but it was almost too much."

"Really, I held right on and smacked them all right in the middle."

How can three talented shooters have such a wide range of results? I thought it was condition changes that occur from shooter to shooter that could not be seen. Or maybe its the way each scope is set up on the rifle. What if the scope is mounted on a rifle in such a way that the vertical cross hair is not in perfect plumb to the rifle? Or a problem even harder to detect, what if when turning the target knobs to dial in the correct amount of elevation, the center of the cross hairs moving up and down are not exactly perfectly plumb? How far off do things have to be before it matters? This concept of keeping everything perfectly straight is not new, I’ve been doing that for years. I vise up on a rifle and place a good Starrett bench level on the receiver rails and make sure the cross hairs follow a line I have drawn on my shop wall. I needed these questions answered, so on a no wind day (for New Mexico that is a 3 to 5 mph wind) I experimented. I had two rifles chambered for the new 6.5 Creedmoor. Our shop built both rifles and they were identical set ups both having their scopes mounted in the conventional manner. There was a minor difference between the two in that one had a Leupold Mark 4, 6.5x20 FFP with a TMR reticule and the other had a Leupold Mark 4, 8.5x25 FFP with a TMR reticule. Both rifles had a good 100 yard zero. Shooting at a 12"x10" steel plate at 755 yards with a 3 mph wind from 3 o’clock, using a center hold, The shot from the first rifle hit just off of the left edge exactly where it should have and the shot from the second rifle hit ¾ of a mil to the right. At the range, I loosened the rings and rotated the scope on the rifle that was shooting too far right, so minutely that it was almost imperceptible in fact I wasn’t sure I even rotated it. Shooting again at 755 yards the point of impact moved about ½ a MIL left just off of the right edge. With a 3 mph wind from 3 o’clock using a center hold, it should have been just off of the left edge. I rotated the scope again in the same direction, and it moved another ¾ MIL in the same direction. Now it is shooting too far left. The other rifle that I left alone did not change point of impact proving that conditions were consistent. Simple fact, scope mounting matters, a lot! My next question was how can I make sure I attain the "perfect scope mounting job". I can’t take every long rang rifle to the shooting range and mount and remount scopes until everything works right. I MUST have a reliable method to perfectly mount a scope in the shop and know without question that it will function 100% correctly in the field. I set fourth to design and implement a system that would do just that.

The new system must secure the barreled action with the scope mounted in such a way that the centerline of the scope and the centerline of the rifle’s bore are both exactly in the same vertical plain. Then, dial the elevation knob through it’s entire range while looking through the scope making sure the cross hair’s center never leaves a perfectly vertical plumb line. Rigidity is the key. It is absolutely imperative that operating the target turrets over and over again causes no detectable movement in the assembly. To make a long story short, we designed a carriage assembly very similar to that of a rail gun. That carriage rigidly holds the barreled action and scope perfectly plumb enabling the operator to simultaneously operate the elevation turret through its complete range and view its movement over the perfectly plumb line. I obtained a perfectly plumb vertical line using a laser level on my neighbors building 35 yards from the shop. This eventually evolved into a grid with MOA and MIL marks accurately drawn on it so that scopes could be evaluated as far as their true movements but that is another story.

Using the new system the scope on the problem rifle was rotated in the rings so that it accurately tracked on the laser line. Another trip to the range. I use a software program on a PDA called Field Firing Solutions from www.precisionworkbench.com . After verifying a 100 yard zero the target at 755 yards was engaged. With a 7 mph wind from 135 degrees my software called for and I dialed in, 17 ¾ MOA of elevation and a hold of .4 MIL right. I got a center hit with both rifles. This was a great success.



Conclusion:

I have always taken great care mounting scopes. The techniques I had been using were perfectly correct in theory. I simply wasn’t getting the degree of accuracy required. Originally both rifles went through the same process. I got lucky on one, not so lucky on the other. The difference between right and wrong was unperceivable using our old system in the shop environment. I could not get satisfactory results until I built a very elaborate fixture that could rigidly hold a barreled action with the scope mounted in such a way that the vertical centerline of the bore and the vertical centerline of the scope had no more variation than one thousandth (.001) of an inch in six inches.




Some rifles are just good shooters and they make it easy for a good shooter to shine. The performance of some rifles defies logic, and makes it impossible for the shooter to excel. The shooter questions their ability to dope wind. They get frustrated and filled with self doubt when in reality they might just need to have their scope properly mounted.

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Oops

I'm sure there's good info in rc's post, too long to hold my attention tho

pretty simple and cheap to get a 36" target,a plumb bob and a piece of string and go shoot..which is ultimately what you're going to end up doing anyway if you actually want to KNOW..

755 yards says it all. What he says is correct for 1000+ plus target shooting like this one I own (funny how all these "experts" never post pics of 1000 yd+ rifles).
It is shot off a bench at gongs and paper, will never be hunted.




Hunters, as the best Elk hunter I ever knew believe "you a'int huntin Elk till you can smell them." That culture I also learned from being a bow hunter for 40+ years. Sniping at some big game animal who has no ability to use his natural defenses, with your computers, wind meters and knob twiddling is IMHO not hunting, it is target shooting using live targets.

You might note that many of the well known writers in responsible sporting publications are now starting to be critics of "men" who wish to exchange technology for real hunting skill.

It is becoming a cultural divide where traditional hunting like stalking and killing a Whitetail at 75 yards with an open sighted 30-30 94 Carbine is becoming a lost skill in favor of sitting in a camo blind and sniping that same deer at 600 yards with a 7 mag Remington Sendero.

This is my big game hunting rifle. It is reasonably high tech (as Askins the elder predicted in the 1930s), the scope (Nightforce) cost more than the rifle and I am 100% confident of its 1 MOA performance to 400 yards.(as far as I put it on paper). it also handles like a fine sporting clays shotgun, a quality unknown in these sniper wannabe bolt actions.
Never had to fire more than one and greatest distance was 275 yards. A 300 winmag with 168 TSXs will handle anything living in NW WY.



Just my $.02 from an old man who has been hunting longer than most people I see afield have been alive.

We all know that Brownells sell many fine products, intended to ease and improve our life as firearm enthusiasts. I started using this product a number of years back and have really fallen love with it. It is used in conjunction with a plumb so, you know the reticle will truly be vertical as long as you get the rifle trued up. If you can believe a scope, sitting in the rings, sitting on top of the mounts which are sitting on top of the action are in perfect vertical alignment than this is your Huckle Berry.

http://www.brownells.com/gunsmith-t...ertical-reticle-instrument-prod6097.aspx

As a long and ultra long range shooter, I can testify to it's ability to get your reticle truly up and down.

Alan

I looked at it on Brownells. Can you explain how it is used as they don't ?

Thanks, Larry

You're fulla schit,from someone who's killed more elk than you.

15 posts until egos set in. The fire continues to cool.

Hmmm...

One can level the scope to the rifle however it never means you will not cant the rifle one way or the other when shouldered effectively moving point of impact at 500 yds right or left by a fair margin.

My basic analogy of 4agers proposal is without a level on the scope that is set 90° from the vertical on the reticle it will serve no practical purpose and in fact may even cause harm or a false sense of security.

I would also propose that if one does not prefer a level on ones scope setting the scope to hold vertical from your natural shouldered position will serve one far better than setting the scope to be vertical with a rifle that shoulders canted.

My personal preference is I set my scope to facilitate my natural field shouldered positions and run a level that is properly adjusted to the reticle.

If I was into competition then I'd get the proper equipment and go RCs method. If 4 ager is referring to setting up a proper long range rifle he is a mile off.

Shod

To those of you who have provided info. on techniques and tools to do a better job of properly mounting and leveling a scope...THANKS! It's a job worth doing as well as possible to limit the chance of a poor hit on the animals we hunt. I've learned some things from you.

I shoot benchrest where a level scope is very critical. To do that, I first level the rest I'm shooting off. Then I level the target (could also use a plumb line) and line up the cross hairs on edge. When shooting my bench rifles I always, first, level my rest. My stocks have flat bottoms so this assures consistency.

For a hunting rifle that will not be shot off a perfectly level rest, it's not that important. For my hunting guns I just put up a plumb line, get in the position I will typically hunt from, and aim at the plumb line. Repeatedly, go in and out of your shooting position to sorta get an average or typical hold. Then adjust your scope until it's level from the way you hold the rifle. Our bodies being contoured as they are, your rifle when you hold it will have some degree of a cant. As long as you hold is fairly consistent, this will work. If your hold is not fairly consistent, leveling your scope won't matter. Unless you have an astigmatism, trust your eye.

If you're dialing much elevation the vertical crosshair needs to point straight down at the center line of the bore, and the horizontal crosshair needs to be horizontal when you shoot. Otherwise dialing elevation will introduce a horizontal component as well.

4ager, you have a PM.

All this "proves" is that you don't understand the meaning of the word unethical.

The dude uses a leadhead sled....what did you expect?

Not much. I just have an aversion to hogwash.

Larry is a proven, known con artist. He defines unethical.

Rick allows him to abide here. Why, is the root question (pun there).