Yep, that's how my home made one is supposed to work but I haven't been able to get it to ignite so far. As for ground squirrels, I take care of them with my air rifle. I had dozens of them all over the place when I moved in ten years ago. A friend and I shot maybe fifteen of them one afternoon. After that I would plink them as time went on, and now I only have maybe one to three new ones each year. The new ones seem to know about me, because they hi tail it at first sight.

Your are correct, my memory failed me. From the instructions: open oxygen control knob one and one half turns from full closed position. Open propane control knob 1/8 to 1/4 turn from the full closed position. Injection time is 30 to 90 seconds depending upon soil type for ground squirrels. The mixture goal is less than 2% LPG and 98% compressed oxygen. The manual says the concussive shockwave is over 10,000 psi in the tunnel system.

Great info, thanks. I'll use the propane/oxygen ratio range when I try it this summer.

"I smell varmint poontang" !