I have a side parallex adjustment on my scope, I never use it, is it really beneficial.

Parallex becomes a problem when you use what would nornally be a big game scope at rim fire ranges. Most big game scopes are set to be parallex free from 100 yards on out where as most rim fire ranges are at 50 yards and less. You get a parallex conflict. The answer is depends on what you are doing with the scope. Sometimes all the extra bells and buttons on our gear just cause to confuse us. I have a hunting friend who has so many gadgets that by the time he is ready to shoot many times there is nothing left to shoot at.

Is it beneficial? Perhaps somewhat, depending on your usage.

Parallax error is the apparent movement of the crosshairs on the target as the eye moves laterally within the area of the sight picture.

Parallax error is caused by the differing placement of the eye within the sight picture from shot to shot. The A.O. or other parallax adjustment can cancel the eye misalignment error at a given yardage.

With a stock which fits you well (providing firm placement of the cheek against the comb when the eye is aligned with the scope), there is very little change in eye-scope alignment from shot to shot. Theoretically, with consistent eye alignment, there is not need to correct parallax, even if the potential parallax error is relatively large.

When the parallax is adjusted for a particular yardage, then it doesn't matter where the eye is within the sight picture, because there will be no apparent movement of the reticle even when the eye is at the extreme edge of the sight picture.

Potential parallax error with the typical hunting scope (usually set for 150 yards) is fairly small (at most, fractions of an inch), by hunting standards. When shooting benchrest or at small varmints at long range, shooters usually like all the advantages they can get, therefore these applications generally use a parallax adjustable scope.

I always counsel AGAINST an adjustable parallax feature on a big game hunting rifle, since (1) its accuracy enhancement is irrelavent for a target the size of big game, (2) it will nearly always be set a some distance other than where the game presents itself, and the last thing you need to be doing is fiddling with your parallax adjustment when trying to get a killing shot at a trophy animal, and (3) the adjustment mechanism is just one more thing that CAN go wrong with your rifle/scope/ammunition and there's no sense in introducing more potential problems to your hunt. For all the same reasons, a parallax adjustment makes good sense on a target/varmint rifle.

Stonecreek is on the money. Adj Obj scopes are great on my target & varmint rifles, and possibly on long-range hunting rifles, but not worthwhile on standard hunting rigs. I've got several of them. Guy

I like AO for varmint scopes.
There is a world of difference between whacking a deer or elk in the shoulder or ribs than trying to hit a groundsquirrel ate 235 yds. with a mid-1930's K-Hornet with a 4x scope.
A big game scope will almost NEVER give you the kind of clarity and definition you need for a tiny target 1 1/2 inches wide at most over 150 to 175 yds.

Dave 32-20

I have a handgun scope that the Parallex will move a good foot in any direction. I won't give the name of the company which makes this piece of crap, but its initials are BSA.