Long range shooting scope setting

[Guest]

I typically shoot my 300 Ultra Mag with the scope setting at 8 power. The scope is a Burris Signature 4 x 16 x 44 with the Ballistic Plex. I curious, when shooting at 300-500 yards if I increase the power will this alter the bullet impact point?

 

[Guy Miner]

This is something you need to check at the range.

It shouldn't change your point of impact - but sometimes it does. When a scope does that, I get rather irritated and it has a very short life in my inventory. I might tolerate it for a scope intended for shorter range shooting only, but I usually use a fixed power scope for that stuff anyway.

Burris has a reputation for building a quality product, so I'd hope it wouldn't shift, but you're the only one who can tell for sure. Set up nice and solid at 300 - 500 yards, fire a group at low magnification, another at 8x and another at the highest magnification.

I hope it works out well and all those groups land on top of each other!

Guy

 

[Antelope_Sniper]

Don, a shift in bullet impact is very common in variable power scopes. Year back on of the majors attempted to capaitalize on this by advertising that on their 3-9x scopes, you could raise your point of impact 2" at 100 yards by decreasing the power setting from 9x to 7x. Most variable powers scopes will shoot to the same point of impact on their lowest, and hightest settings, but inbetween, it could be different.

Like Guy said, the only way to know for sure is to check it at the range.

 

[Murphdog]

A number of years ago I had a 3-9 scope that after a hundred or so shots would loose the parallax. Drove me nuts the first time until my father-in-law (Pa Pa)found the problem. Sent it back to the factory when it came back it did the same thing. I sent it back and traded it off once it came back.

The reason I bring it up was that I thought oridginally the zero was moving with the magnification settings. I was sighting the rifle in on the 9X but when hunting in timber the scope was set at 3X. I had a couple of missed deer. Would take it back to the range (9X)and it would shoot fine. When I checked the theory of the POI moving with the magnification I found that was not the case. Pa Pa had seen it before and showed me the problem.

Put the rifle in a rest and look through the scope. Then change angles at which you look through the scope (the scope will not be in full view) but do not move the rifle. If the cross hairs don't line up on the same point regardless of the angle you are looking you have a parallax problem. At the bench you will align the rifle perfectly with the target and have a full view. In the field shooting off hand or using a make shift rest you don't always get it perfect.

 

[JD338]

The scope should not change POI when you change the power setting of the scope.

JD338

 

[DrMike]

I've shot a wide variety of scopes at the bench during the past number of years. Few shift POI with change in power setting. Since the reticle is in the second focal plane for most scopes sold in, reticle size does not appear to change, which obviates shift in POI for all practical purposes. If a scope is shifting POI, there would appear to be a more serious issue.

 

[Guest]

Thanks to everyone that replied, your input is really appreciated.

Don

 

[Ridge_Runner]

I shoot alot at 800 to 1000 yards, most probably your problem is parralex, without a parralex adjustment its very diffacult to keep a consistant POA at extended range if you can't set the parralex for the range your shooting.
RR

 

[chet]

Don, I just wanted to make sure you fully understand your ballistic plex system.

The center, or main crosshair will stay centered or "zeroed" at all magnification levels. However, all the holdover points (hash marks) that are underneath the main crosshair WILL change POI with power adjustment.

These "hash mark" holdover points are designed to ONLY function while the scope is on its highest magnification. These hash marks must be ignored while the scope is set at any power other than MAX.

I have one on a 26-06, the gun shoots too fast to match up to the program, however on 12x instead of 14x it matches up pretty close. It is usually possible to custom tune the scope to your load using the power ring.

I hope I havent confused you, but to make a short answer: the POI of the holdover marks DRASTICALLY change with power adjustment. The main crosshair DOES NOT change POI with power adjustment.

I know I really suck at explaining things

A good way to help understand this is to stick a boresighter in the end of the barrel and watch the main crosshair stay on target while you adjust power..... you will also see the holdover marks track up and down the grid as you adjust the power ring.

godspeed

 

[Greg Nolan]

Exactly
Center will stay centered but the bdc marks will change. You can see it easy by just looking at your far off target and changing the power ring. The trick is to find what power setting works best for your trajectory. It may or may not be the highest setting but usually is.
A way to do this is to pick your sight in range. Say 200 yards. Sight in. Now set a target at 300 and shoot dead center at it at max power with the crosshairs, not the hash mark. Now look at where the bullet hit. Is it exactly at the first hash mark? If you hit above the hashmark turn your power ring down slowly while whatching the hashmark line up with the bullet hole. When it lines up note what power you're set at.
You can do the same thing at 400 and see if it matches up with the second hash mark etc. By the way, remember that if your hitting say 6" low at 400 yards with the second hash mark you can adjust your scope up 4 " to hit only 2" low at 400 and it will change your point of impact at 200 by only 2" and your point of impact at 100 by 1". It's more important to have your bullet able to hit the kill zone at all ranges using the bdc reticle than to be able to hit dead center at any specific range . IMHO
Good Hunting
Greg

 

[hardpan]

If your zero changes, then I would not use that scope. The hash marks are typically set for a 200 yd zero, and a specific BC and velocity. For the Zeiss scopes, there is a program on the internet and instructions on how to use the hash marks... Mine is about a 200 yd zero and the actual zoom amount for the hash marks to be correct with my loads is about 10.5 more or less. But, I still use a ballistic chart, practice a various ranges, and a range finder. Leaving anything to doubt is crazy given that we load and practice all year long, hunt for several days, and if we are lucky, we take 1 shot.

Hardpan

 

[Ridge_Runner]

I always sight in on highest power (in my case its 20X), if your shooting 500-600 yards you can use the extra power. at close range turn it down, if it shifts a bit it won't be off as much at closer ranges.
Try this test, set your rifle up on a bench, sandbagged well or in a vise. use a high definition target with the scope on its highest setting set the parralex as precise as you canthen turn the power ring and watch the crosshairs and see if they move on the target.
RR