Getting the Rifle Ready for (fill in critter name here) Season Part

Arizona Outdoorsman / AZOD

Getting the Rifle Ready for (fill in critter name here) Season

Sighting in the Rifle Part 2

By Don Burke

AZOD Contributing Writer

Zeroing should be done on a calm day, less wind the better, and a temperature approximating hunting conditions, if possible. Use a sandbag or similar steady rest under both the forend and the buttstock. Remember that the barrel should not touch the rest. This will adversely affect accuracy. Shooting from a solid rest position removes most shooter error and verifies the rifle's accuracy ability. If you also want to verify your actual zero under field conditions, you would shoot the rifle after it’s zeroed, using field shooting positions such as offhand standing, kneeling, or prone. Things that come in handy for rifle zeroing would be a shooting table, shooting mat, sandbag or similar rests, and spotting scope. A target graduated in inches would make it much easier to calculate sight adjustments.

Let’s say our rifle was sighted in with a given load at 100 yards. After firing a three round group we note that the group itself measures 2 inches but is 1 inch below the point of aim. Why would our zero with the same rifle/load from last year change? One reason could be shooter error. Try firing a second group to see if you get the same answer. When you were cleaning the rifle, did you tighten any stock or sight/scope mounting screws?

Minute of Angle. I'm going to skip the scientific definition here and go right to the good stuff. MOA translates to one inch at 100 yards. When we say "that rifle shoots MOA" we mean the rifle is capable of putting all the shots into a one inch group at 100 yards. At 200 yards the group would be two inches. At 300 yards three inches and so on.

I'm sure that there are benchrest or precision rifle shooters out there who are unimpressed by a rifle that holds MOA. Well, maybe true, but for the average shooter or hunter, a rifle/shooter combination that can hold 6-8 inches at 100 yards under most conditions is just dandy, I think.

Should we worry about temperature? Well, if you sight in your rifle at 90 and then expect to make a 500 yard shot in 30 degree weather you might want to do some actual shooting at those temperature and ranges to make sure, because a three MOA error at 500 yards would be about 15 inches. If you are like most of us that expect and generally get a shot somewhere out to 100 yards or a little mite further, this isn't going to affect things at all as long as the temperature difference is not that great. Remember one MOA for every 20 degrees higher the temperature the higher the strike of the bullet. The lower the temp, the lower the strike on the target. If you sight in your rifle at 70 degrees at 100 yards, then shoot it in 90 degrees, you may see the shots strike one inch high. If you sighted it in at 90, and shot in 70, the shots would be low. But remember the difference may only be about an inch at that range. Probably not that significant considering most hunting conditions.

Back to the shootin' part. Our group was one inch low. If our scope adjustments are graduated like most- in 1/4 minute of angle adjustments, 1/4 minute at 100 yards is 1/4 inch. Four clicks of up adjustment should put the group right where we want it. One thing that is common to some scopes is that after making a sight adjustment, the scope will change slightly after the first shot.

If you are shooting a new rifle/scope combination it might be a good idea to boresight the rifle first then begin sight in a 25 or 50 yards before going out further. The rifle can be zeroed for any range however I find it easier to zero at 100 simply because MOA calculations are easier. - AZOD -