auger for rocky soil- recommendations needed

I want to buy an auger for making holes in the soil, both for planting and for the posts of a mobile electric fence.  The soil here is incredibly rocky.  

Does anyone have a recommendation for what brand to buy?  Or is it a stupid idea to get one when the soil is rocky?  
Are there any other recommendations for making holes in rocky soil- both small holes for the electric fence posts and larger ones for planting things?

I was considering this one at Amazon, it gets a lot of positive reviews but also a warning that it's a frequently returned item.  I'm happy to shop some place other than Amazon, I hate to support them but it was an easy place to look at a wide selection.  
https://www.amazon.com/dp/B09XMTTFPR/?coliid=I1ZQ3CBOJ8CWZW&colid=9M3ABGWFQLEU&psc=1&ref_=list_c_wl_gv_ov_lig_pi_dp

I want to spend as little as possible, but can spend up to $50 or a little more if someone says it's been good in rocky soil.  Thanks

Hi Jolene,
I have used this type of auger somewhat extensively (worn out at least one in caliche soil in AZ), and that particular one is a 3/8in shank. I suspect it would snap after the first rock or two. Also, these depend on your drill, so the best augur on a wimpy driver will disappoint. Then, there is "rocky" and there is "rock". My property has rock, and I use a rotohammer if I have to put electric fence posts into it. Some rocks in some (relatively loose) soil will respond much better to a big auger like that.

You might do a sort of test on the soil, with a trowel augered down vertically to the depth of the desired hole - if you can make a trowel do it with some patience and effort, an auger like this will do it with less effort and faster. If you think the soil would still be good to drill, I'd first look for a 1/2in shank on the auger, as long as you have a 1/2in-chuck drill. 4in diameter is big. If you want a big hole, perhaps drill a 2in diameter hole first, then a 4in to break in the sides, but that depends on your posts and the needed hole size. Remember that your hands have to react the forces, and a 4in auger will kick hard on a rock. It's like a gear ratio. I've tweaked my wrists doing this, and I am pretty careful with tools generally. Brace the drill with your leg.

As far as a suggestion, this one is smaller diameter and looks substantially easier to use while standing, with a 1/2in shank. That's not an endorsement, but it ticks the boxes I suggest above.

A digging bar  is another option, will not flinch at rocks, but it's heavier. If you have physical limitations, it might be more difficult to use than a drill (though the drill will hit you hard when the auger hits a rock!). It has the advantage of not needing batteries, and probably lasting for decades. You might find one at your local hardware, too. You can get pointed tips that would be better for just the fenceposts, or flat tips for digging.

Best of luck!
Mark

What kind of rocks do you have?

Something like that would never work in my rocky soil because my rocks require something with a tractor attached.

Good evening Jolene!

I live a few hours away from you, and I'm sympathizing with the rocks. My soil has a lot of small rocks with the semi-frequent potato sized rock appearing as I dig. Sometimes I get lucky and find an entire boulder, this usually happens when the spot would be 'perfect' for a certain plant.

I would NOT recommend an auger style digging tool, instead I would point towards a digging bar styled tool to be able to have leverage on your side. These days, I actually use a thick flat head screw driver if I'm transplanting into the ground with decent success.

Here is an older thread of mine on the subject of rocky soil focused tools.

No hand portable auger (drill or engine powered) are good for anything bigger than a marble. The heavy duty ones won’t break on potato sized rocks, but they are pretty likely to break you. They will kick HARD.  I have had a lot of bruises including a few bone deep.

I use a combination of a heavy drill with auger, a digging bar to pop the rocks when I hit them, and a regular post hole digger to enlarge and finish holes if needed.

Thank you for all the responses.  
My soil has a lot of shale- flat rocks in it, sometimes quite large.  I guess the auger was wishful thinking.  I used one years ago when volunteering for something and it made things so fast and easy, but that soil wasn't rocky at all.  
I will get a digging bar and be prepared for lots of digging.  It seems I will often need to make bigger holes than necessary and back fill around the electric fence stakes making it's use much, much more work than I expected.    

Just throwing out another option is those attachments for a pressure washer. They fire water into the ground to loosen and move things aside. More mess, but less grunt work.