2 questions...

[fisrtcoueswas80inches]

ok one question is as follows: i have heard that with a variable power scope, when it is turned up in power, that the point of impact changes. is this true? i shoot a leupold vari-x III. if i sight in on about 7 power and then turn it to 10 power at say 300 yards, should it still hit where it is sighted in or will the poi change?
2nd. i know that barrels shoot better when they are cold, why is this?
casey

 

[RLH]

it used to be a problem with some scopes. anymore, a good scope shouldn't move a noticeable amount. used to be an old "wives" tale that when you increased the power that you had to shoot lower too. when you increase or decrease magnification it can move the zero a very small amount, but probably not enough that you could tell it, and definitely not enough to affect your ability to hit game. snipers and other marksmen use variable power scopes all the time.

 

[Buckrub]

I think the variable scope issue has been corrected for at least the last 20years, at least with "good glass". The cold barrel issue is because as the Bbl. heats from shooting the metal expands and sometimes applies pressure to the bedding of the stock, which in turn affects accuracy. That's why you have "block-bedding", "fiberglass-bedding" and "free-floating", to reduce the effects of a hot Bbl. and improve accuracy.

 

[SoTX]

I am no expert but, the only time I have experienced that is on a Leupold Vari X III 6.5 to 20. I would normaly sight in and shoot with it on 10 power with no problems. However when I would shot with it on a higher power, say 16 or 20, I would not group as well. I am not sure about changing point of impact as much as it is distortion. Remember two you must alow for bullett drop. So if you sight in at 100 yds and then shoot at 300 yds your bullett will impact much lower than at the 100 yd range.
As far as barrels go, when they heat up from shooting they tend to expand and move. Now with that said a good rifle barrell will move but not that much where it realy makes a drastic difference.

 

[400bull]

For the ultimate in accuracy consistancy is a must. It is my understanding that a heated barrel will shot just as accurate as a cold barrel as long as the barrel tempture stays the same. In all case the barrel will heat up some after each shot. As the barrel heats up it will start to expaned. This will cause deffent preasure points on the bullet and barrel. It is the defferent presure points that cause the POI to change. Thats one reason why you should let you barrel cool down between shots.

400bull

 

[RLH]

sotx, when you crank it up to the higher power it just makes the group look bigger.......i apologize....just coulnd't help that one. go to a target shoot, where they are real serious, they almost all use fixed magnification scopes. but a lot of snipers use variables. for practical purposes, it's just whatever a guy wants to use. i keep my 3.5-10 on 5x. if something is way out there i crank it up. i can remember reading articles years go about groups moving around when you increased magnification. they would still shoot the same size groups, but they would move around a little on different powers. never really understood why. but it wasn't enough to worry about for hunting purposes. i know one thing, my groups get bigger with age. just ain't as steady anymore. must be that dern wore out variable power scope.

 

[warbird]

It's th same reason why all police snipers shoot a fauled shot from the rifle after they clean the rifle.They have to know where the bullet placement will be everytime for obvious reasons, now I will say I have a rifle that shoots better when it's warm, Why who knows. and yes some cheaper scopes will change point of impact because it's the internal mech and type of glass used changes the reticals so also the POI changes. but their right most quality scopes fixed that problem.

 

[AZBuckSnort]

LAST EDITED ON Feb-15-04 AT 06:16PM (MST)[p]Casey,
Is it worth not knowing where your rifle and bullet combination impact down range at different magnifications? Why not be sure by setting up a target and working through the various "powers" of your scope so you'll know and not just take it for fact without verifying? All it's going to cost you is a bit of time and ammunition.
It's true that the majority of currently manufactured variable scopes should shoot to the same point of impact within the scope's full magnification range, but what if YOURS doesn't? I can tell you about a Redfield 3x9 scope that didn't in Utah and cost me the best mule deer buck I've ever had in my crosshairs. In that case the scope's POI was 6" high and 5" left on any power above 6X. Redfield corrected the problem free of charge and quickly; however, it didn't help with that fateful day in southern Utah. The bottomline, just check your scope for yourself and eliminate the worry.
For what it's worth, my experience so jadded me that all my serious hunting rifles carry only one scope: a Leupold 6X42MM with multi-coated lenses. Fixed scopes are generally lighter, smaller, and with no moving internal parts, far less susceptable to any point of impact shift.
Good Luck with you scope and your 2004 hunting plans.

 

[monsterbuck89]

You shouldn't have any problems with a Vari-X III, but I would question an older scope. I have never shot through an older variable scope but would think that may have been an issue then.