Thats what I was thinking, if the jacket is thick enough, you might need a few more milk jugs. I hope you'll do a test for us.
True story... we go up to the range, and there was a group shooting their deer rifles at targets taped onto a 16-18" diameter cut off stump not noticing any movement of the stump, We begin shooting the FTX factory loads into the stump after they are done, and the stump rocks back about 30 degrees with each impact. Gunny pulls out his magtech loads, which immediately cause the stump to fall over backwards!
The hunters were pretty impressed, as was I.