Here is an interesting question I received on one of the forums:
"I searched the forum for answers to no avail.
I am not a PRS shooter.
In my context, I prefer to shoot standing, kneeling, sitting, and prone using sling-supported positions i.e. no bipods or tripods etc.
Taking my context into account, I am wondering if you would have any thoughts on what the maximum magnification a scope could have, while being employed from sling-supported shooting positions, without being so powerful as to make shooting impossible due to image wobble?
For example, I am confident I could use a 9x from a sling-supported standing position, but a 12x or higher I do not know.
Does my question make sense?"
This is a little bit out of the left field since comparatively few people these days shoot with support slings. It so happens that I do, but I have to admit that most of the time I shoot with a support sling uses something that is more similar to a Ching sling than to a traditional loop sling. I do have one proper 1903 sling, but it is attached to a rifle that has dual aperture iron sights on it. That particular one is a biothane sling from Turners. It is a pretty respectable shooting sling and an even better tourniquet.
Most of the sling I use come from Mr Rifleslinger: https://rifle-craft.com/
I believe these to be the best general purpose two point slings on the market today and of the four models he has produced over the years I have at least a couple of each.
The gentleman behind this company is the same guy who wrote what is likely one of the most extensive series of articles on shooting with a sling, practical shooting accuracy, shooting quickly with a boltgun and a bunch of other things. He stopped updating his blog, but for now it is still up and it is a very worthwhile read: https://artoftherifle.com/
Now onto the question at hand: how much magnification can you use when shooting with a support sling? The answer, unsurprisingly, is a resounding "it depends".
The wobble you see in the sight picture really does not depend on the magnification. The magnification makes it look a little different, but in terms of actual POA wobble, all things being equal, it will be exactly the same on any magnification. The natural question is then why not just put the scope on the highest magnification, then? Well, because all things are not equal. Not all shooters are equal. Not all guns are equal. Not all scopes are equal. Not all shooting positions are equal.
There is a nasty trick that our bodies tend to play on us when we are aiming: when we see a wobble in the sight picture, we start subconsciously trying to correct it which only increases the wobble zone. That is one of the primary reasons to to not go too high up in magnification. A lot of that can be trained for and some people (not me) are better at it than others. There is really no way to predict how exactly that will pan out for each individual shooter. Personally, I tend to use the lowest magnification that allows me to see the target clearly enough. Naturally, if you happen to be shooting at something comparatively small, a little more magnification will go a long way.
It so happens that I have done a lot of shooting with a support sling and a 3-15x50 scope (TT315M). The way it usually works out for me is that 15x is perfectly usable when shooting prone, but for everything else I am a little more accurate with less magnification. I can't suppress my brain's subconscious attempts to correct things well enough. Perhaps, I am not good enough at finding my NPA, but to be honest, I do shoot reasonably well with a sling. I have had a lot of practice.
Fair disclaimer: with a sling I mostly shoot prone, sitting and a few version of kneeling. A lot of people seem to like the squatting position, but I am a bit too old and fat for that one. When shooting standing, the sling might provide some psychological help, but I do not think it actually stabilizes anything. I have tried it a few times and I actually shoot worse if I try to use the sling while standing. I do tend to drive the gun while shooting standing rather than try to settle into a wobble zone. It seems to work a little better for me.
Another factor to consider is that your eye position with respect to the scope is going to be a little different in different shooting positions. In practical terms, that means I will set the scope up so that it is perfectly located for shooting slung and prone. When transitioning to other shooting position, there usually isn't enough eyebox to use the same high magnification without weirdly contorting my neck even if I wanted to. In order to keep my neck relatively unstressed, I HAVE to drop the magnification a bit.
It does vary from person to person, so the only way to really figure this out is to experiment. I have done exactly that. When prone, I seem to end up around 12x most of the time whether shooting slung or off a bipod. When shooting offhand, I shoot best with the scope around 3x. Sitting position is somewhere in between and it sorta depends on how forgiving the eyepiece of the scope is.
