Long range shooting problems.

J

John68

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I am new to long range shooting and am having some problems with my setup. When I zero the rifle at 100yds and then make the elevation change and shoot out to 500yds, I get the proper elevation but the grouping is about 8-10" right. The wind is not a factor and as far as I can tell I have mounted the scope properly. I have never had a problem with mounting scopes on hunting rifles but then again I don't expect them to shoot past 400yds.

What really gets me is that I had the rifle shooting just perfectly and any elevation change had no effect on the windage of the shot. I had shot it all the way out to 900yds and with the exception of the wind the shots were hitting bang on. Thats when I decided it was time to finish the gun and of course the scope came off to do so.

Like I said to start with, I am new to LR shooting so maby I am missing something really simple. As with all my firearms experience I am just learning as I go so if anyone has some insight into this problem it would be much appreciated.

Thanks

Dave
 
could your scope be tilted a degree or so? If the scope is not perfectly vertical, you will get windage changes along with elevation adjustments.
A scope leveler will fix this.
 
Have you checked your scope for "Repeatability". At 100 yds zero your scope, then move the horizontal left 5 min. fire 1 shot. then move your verticle up 5 min. and fire one shot. then move your horizontal right 5 min and fire one shot, then move your verticle down 5 min. and fire. you should be back on the bull where you started. If not, that is your problem and you need to $$$ up for a good scope.
 
Every time you shoot your "zero" will be different, at any range, off course the longer the range the more different it can be. If you use a level and your windage is consistently different at longer range then your scope (if you are using scope) is suspect. With irons your rear sight is probably not plumb. A level IS critical. Refer to "Canadian Bisley Shooting" for reference on what cant does to you.
 
What type of scope?

Are you rings on backwards, or loose? What type of bases, anything moving?

If a scope is stressed when reinstalled, it can hang up internally. Scopes can fail. Lesser scopes will move windage when all that is desired is elevation.

More details please...

Jerry
 
Just a thought but everyone probably cants a rifle a little bit. With receivers not always perfectly level in stock, mount holes drilled slightly one way or the other of top dead centre, variances in hold,variances in mounts/rings. I've often wondered how much of an effect of a small cant has at very long range. Even the devices that slide onto bolt lug tracks assume that receiver is level in stock and mount holes are top dead centre. If for example, the crosshairs look straight to the shooter(as he has them mounted) but line of bore is slightly right of the line of sight(canting to the left)....then we adjust scope so that windage appears right now at say 100yards....would'nt the bullet appear to drift to the left the farer downrange it goes? Just a thought. Everytime I pick up someones rifle and look thought the scope(or vice versa) the crosshairs hardly ever appear completely straight for my eyes or theirs.
 
The type of scope is a Leupold MK4 8.5x25-50mm mounted in leupold rings and base on a custom rem 700 .338 RUM with a 30" BBL. The gun shoots excellent and the scope tracks perfectly. Like had said originally, the set up was working fine before I took it apart to refinish the gun.

I'm guessing that my problem has something to do with the remounting of the scope. I tried to mount it as level as possible but all I did was eyeball it.

I agree 100 percent with Randy's post. I guess my real question is knowing that everything was fine prior to removing the scope/rings/base, is there a device or a method to ensure that the path of the bullet is directly in line with the line of sight when mounting a scope. Now that not only includes any canting of the scope but the positioning of base as well.

I have had a few suggestions on how to do this which involve levelling the rifle and then using another level to level the scope or else looking through the scope at a hanging string to make the adjustment. I plan to try these methods and see if it helps but if anyone has any more advise on the subject I gladly welcome it.

Thanks

Dave
 
Randy Carriere said:
........I've often wondered how much of an effect of a small cant has at very long range.
Click to expand...

I understand that if a scope is canted as little as 5 degrees (which most people can't even detect), it can change the MPI by as much 1/2" at 100 yards..........

John, here's product that I haven't used, but I've heard a number of people say is quite good.

http://www.deadeye2.com/

Personally, I use a small plastic device that has a buit-in bubble and it sits parallel on the mount, held in place with an elastic rubber band. It has several horizinatal lines on it, which when I look through the scope it allows me to line those up with the horizontal reticle line within the scope. I can't remember the manufactuer's name, bought I got it from Keith at Milcun. It's worked good for me during the install of the last three scopes I've had to do.

Hope this helps somewhat... :)

Regards,
Badger
 
john68, I had something very similar at 300yards. My rifle is generally very consistent. When sighted in windage wise at 100yards...group would be to the right at 300yards. I got windage down perfectly at 300yards thinking that everything between there and muzzle should be perfect but reality was that group printed left on 100yard taget. I think that scope mounting and canting can be the only real problem. I do think that as range increases one could expect bullet flight to move slightly in the direction of the twist, but thats a different topic. With all the variances in manufacturing I think the best one can hope for is a condition where all the little variances are adjusted so that we get scope, crosshairs, stock, rings and mounts lined up to sort of cancel out the errors in each. In this instance probably an injection molded stock would be best for consistent levelness and butt plate straightness/cast off.

A method that I have read but never tried was getting a very straight piece of 1" barstock(about a yard long) and hanging a weighted string from end. Turn on front scope ring with this and align so that string hangs in the middle of the bore. That should make front scope ring adjustment as good as is possible. With this same bar clamped loosely in front ring, clamp rear ring and use external mount adjustments(if possible) so that string remains centered on bore. This SHOULD make scope aligment with bore as good as is possible. As for receiver levelness in stock problems or stock butt casting stock in a canted position??? I never tried the leveling devices I see for sale because I have certain problems with the concept of them. The device that fits onto bolt lug cuts, assumes that these are machined straight and receiver sits correctly in stock. Even the levels that sit on top of the scope adjustment turrets, assume that these adjustment point pushes directly down on the vertical crosshair. I have seen where when turret is level, crosshairs are cocked a few degrees one way or the other. In the end I think its trying to get all these variances to cancel each other out as best we can hope for. It might be what makes those "keeper" rifles where everything just seemed to work properly, line up from day one and are always consistent. Sorry for the long comment/opinion....difficult topic to discuss in a few words.
 
Thanks to everyone who replied to my post.

I have been putting a lot of thought into the problem I am having and I do believe I now know the answer to it so thanks again for all the advise from everyone cause it sure helped. It seems so simple to me now so I figure I’d try to explain the way I look at it and maybe someone else will learn from my mistakes. Or maybe I am completely wrong and someone can correct me.

The way I see it there are two factors in getting a proper scope alignment. The first is making sure that the scope is mounted with as little cant as possible with reference to the rifle. This is important but I believe that it should be done in a way that the shooter finds the cross hairs level when holding the gun his/her way even if the cross hairs are not perfectly level with the gun itself. It does need to be somewhat close, but I think eyeballing and feel should be sufficient. Now that being said it is not absolutely crucial to mount the scope with the cross hairs exactly level but it is important that the shooter keeps the cross hairs perfectly level while shooting each and every time, especially long range.

The second factor (the one I am dealing with) is to ensure the scope itself is parallel to the barrel on the horizontal plane. If not, the path of the bullet and the line of sight will cross on the horizontal plane at what ever point the gun is sighted in at and then will continue to drift apart from that point.

To parallel the scope to the barrel the method that Randy outlined is good provided the front scope ring is centered exactly 90 degrees over the center of the bore. If not the scope will not be parallel to the barrel once the rear ring is adjusted.

The method that I plan to try is
1. Place the gun as level as possible in a vise or something.
2. Place a straight brass rod as close to the caliber being used as possible into the bore and have it sit a couple of inches out each end of the gun.
3. Using a 1 yard by 1” or 30mm piece of “straight” round stock steel or aluminum, tighten it in the scope rings.
4. Hang a weighted string from the center of each end of the round stock.
5. Using the rear course windage adjustment, move the two pieces of string until they are the same distance from the brass rod. Tilt the entire gun one way or the other to bring both pieces of string closer to or away from the rod if need be.

Well I don’t know if any of this makes sense to the rest of you but it makes sense to me so I guess now I just have to prove it. Thanks again for all the input from everyone and comments are still welcome.

Dave H
 
You could always just go to 100yds. Tack up several pieces of paper (graph paper ideal) in a line with an aiming point at the bottom. Make the aiming point a cross with a long horizontal line to ensure that you maintain the same level.

Shoot and dial up the scope. Keep shooting moving the elevation knob to different settings. You will quickly see if the elevation is tracking properly. I prefer this over a scope collimator (I think that is the correct term) as bullets can affect the scope if something is sticking.

Jerry
 
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