I’ve heard that 20 gauge #7.5 works just fine on them.

If you really want to test your skills hunt them with an open sight pistol, I'm not talking about shooting out of a truck, I'm talking flushing them while walking. If you can throw dirt on a running Jack Rabbit with an open sight pistol you're shooting well, hit one and you're just damn lucky. My old S&W K-22 has lucked out many times.

I will tell this as a true story , I don't care if anyone believes me or not. circa 1972 , I was in college at WTSU in Canyon. ( part of the A&M system now)
I had access to hunt a small pasture that had dozens of Jackrabbits, One afternoon, I spied one at about 150 yards looking right at me, I fired, thought I missed , I put another round in the chamber, and watched thru the scope as the animal wobbled , then fell over. I walked to the spot , rabbit was dead but intact.
I found where the round cut thru hair high on the shoulder, but did not break the skin, Maybe scared him to death , maybe just his time to die, or can a
sonic boom be fatal to a hare at that distance ?

I don't know the situation now , but when I was living in the Borger area , there was a ton of land in the Canadian river bottom that was open to public
hunting. Depending on the year , jackrabbits were scarce or everywhere. good luck

MO

When my aunt moved out to west Texas, me and my cousin got in good with most of the local ranchers, and they'd let us shoot rabbits to our heart's content. They were a major pest to them, and a good days worth of fun to us kids.

17 hmr works very well

The best 12ga load I have come up with is #1 birdshot or Lead BB and #2 duplex. If you reload, try it

I won't use a 22 LR on jacks again. They are just too tough. 22mag is a minimum imo

For long range shooting, which is very challenging, 223 sounds perfect

fun

You guys are lucky. Here in SW, OK there hasn't been any jackrabbit in years. We used ride in the back of a pickup at night and shoot them on country roads and wheat fields.

Approximately twenty years ago the rains came at the right time to the Trans-Pecos and all the wildlife populations exploded.

We were shooting at huge coveys of Blues and when we would shoot Jacks and rabbits exploded in all directions. I have a picture of a friend of mine bending over and picking one up out from under a bush. At the end of our hunt he wanted to take some rabbits home to his wife and walked a circle about 70-80 yards yards wide around camp and shot 7. There were lots of jacks that he passed up.