Preferred magnification when shooting offhand.

A long-standing myth is that higher power scopes make the rifle harder to hold steady and shoot accurately. The rifle isn't moving any more with a 40X scope on it than a 4X. The higher power scope will, however, demonstrate how lousy your hold is (speaking only for myself of course). At some point, you want to use a scope of sufficient power to tell you precisely where you are on the target, otherwise, why use it? I would suggest using the highest power scope you can tolerate, while maintaining your hold generally on target. When I shoot my air rifles or rimfires from various positions at 50 yards, I use 16X. As a woods rifle, I would dial it back, because I want a larger field of view if I'm watching something move around.
 
Back when I only shot my R9 springer I could hold 9x pretty steady out to 50 yards. Nowadays I keep my springer scope on 4-6x and my offhand shots 25 yards or closer. Shooting my PCP it's 8x (lowest my scope will go) and around 30 yards. Shooting off sticks has extended my effective range but my offhand skills have atrophied.:(
Wow pretty impressive. Anything above 4x and I wobble like crazy. I need practice
 
2 MOA reflex sight

If the rifle is light enough I've found that more magnification doesn't make me any steadier, and in fact the scope makes it heavier which probably negates most advantages.

If the gun is light enough to be shouldered and shot accurately I will then focus my efforts on dialing in that 2 MOA dot precisely.

I also suggest you use a sling and wrap it around your arm, for me right handed shooter my sling is on the left side and I can very quickly wrap it around to pull and tension the rifle. Adjust the length of sling until you have this movement dialed in and holding your aim steadily will take a lot less effort.

I do have a 4x magnifier on one of my "offhand rifle setups" now as well. I am not so sure it increases accuracy as much as just a better view.
 
I usually use 6X for hunting both for the field of view and because I don't see my wobble so much. It is also enough for me to place my shot well. I know I am still wobbling but it helps me concentrate on squeezing the trigger and following through to not have to watch myself wobble. But I also do not take off hand shots if I can find anything to steady me. I would really not want to take one longer than 25 yards. At some point I will just pass on the shot rather than take a shot I am not confident in. Last one I remember taking was on a squirrel at about 15 yards. In that case I had both my wobble and the fact that my bullpup shoots low at that distance to contend with. But it worked out fine, one shot clean kill.
 
For shooting offhand I prefer open sights or a red dot over a scope. While the gun moves the same amount irrespective of the amount of magnification, the perceived motion through magnification makes me dizzy. In addition, open sites or a red dot will make the gun lighter than if it had a scope, and so for me, easier to hold steady.
 
I was doing quite a bit of offhand shooting today, here is what I found out, shot 3 different airguns with good peep sights,it was fun and I did good, switch to my more accurate PCP light rifle that had a scope at 7power shooting at the same distance and did much worse.
The conclusion is when using a scope for offhand shooting a lower power for me is better.I am talking less than 5x.
BTW good peep sights when you know how to use them can actually be better than a scope, why I think this is,= because your eye automatically finds the center of target,meaning it becomes like looking through a cone that guides your eye to the Bullseye......I am shooting 15 and 30 yards.
Remember shooting my target .22 rimfire at 50 yds offhand with peep sights and did not do good at all.
 
You
I was doing quite a bit of offhand shooting today, here is what I found out, shot 3 different airguns with good peep sights,it was fun and I did good, switch to my more accurate PCP light rifle that had a scope at 7power shooting at the same distance and did much worse.
The conclusion is when using a scope for offhand shooting a lower power for me is better.I am talking less than 5x.
BTW good peep sights when you know how to use them can actually be better than a scope, why I think this is,= because your eye automatically finds the center of target,meaning it becomes like looking through a cone that guides your eye to the Bullseye......I am shooting 15 and 30 yards.
Remember shooting my target .22 rimfire at 50 yds offhand with peep sights and did not do good at all.

I do better as well with lower power … 4x -6x

I started to rethink the high mag vs low mag……and I prefer the medium to low magnification.

Bought a killer high FPE .22 Bullpup from a Well known tuner and this was his rifle with a mounted 4x fixed. Sighted in at 50 yd.
I found wisdom in this setup plus
I shoot Better with lower powered magnification.
 
I think the most magnification you can handle is a good answer. When I started shooting Metallic Silhouettes years ago I was amazed at the magnification the top shooters used some up around 20-30 If I tried using anything over 12 I would start developing bad techniques. Magnification does not make you wobble more but your wobble is magnified you see it better. I usually shoot 1/10 scale rams 45 yards at around 15 power. However their are days that I find myself missing a lot because of snap shooting or jerking. That to correct I can turn down the magnification till I can relax and stop jerking or snap shooting. When coming to a forced FT target I usually turn my scope down 6-10.
 
When shooting my springers I normally shoot between 15 and 50 yards. For a long time I kept the scope on 3x when off hand shooting at these distances. Lately I've been off hand shooting at 5x as I've found I can still hold steady at the higher magnification.
I also do a lot of positional shooting with peep sights. I feel I can hold the rifle steadier than with a scope.
 
I had another consideration in choosing scope…
I usually shoot off hand, and there is usually not a lot of time to set up: otherwise I would take the time to get comforatble and use sticks.
So when time is short, I want to focus on aiming and shooting, not on setting the scope parallax, magnification etc. With large magnifications, there is lot of room for parallax error.
Also, smaller magnifications are brighter in low-light conditions.
I had a classic fixed 4x weaver on my Edgun r5. I have changed it for a classic 6x weaver. Could not be happier with it. The perfect compromise: perfect for offhand, low weight, enough magnification to be accurate at 2inch objects, and bright at dawn.