Thought we could use some action on the forum ;)
I have two XR9's, one in each barrel length, really like the guns. I've not had any malfunctions until yesterday, but that was trying out a new ammo, Freedom Munitions, and it caused problems. Same ammo in my LCR9mm caused every case to split, so its obviously its not top quality stuff, but the price is great.
Anyway, I'm big on gelatin testing, and normally test with leather, fleece, and denim in front of the Clear Ballistics block (left bullet in the photo). I can get a good 14" penetration using CorBon DPX, my favorite ammo. I've had many, many JHP's plug up and not expand at all, I attached an example of Hornady failing in this regard.
Yesterday on a surgeon friend's recommendation, we took it to the next level. 2 layers insulated carhartt, 2 layers sweatshirt, 2 layers carhartt jacket. THEN, 2 racks of pork spare ribs (to be sure it hit bone).
First the Underwood 115 because its so darn hot. Hit bone, went fully through the whole block, but then stopped by clothing draped on the far side (so not much power left). Then DPX, it only made it 10", but it also hit the heavy zipper of the coveralls first (was aiming for it) with the heavy fabric on either side of the zipper.
I was very impressed. The underwood's overall diameter is smaller than the corbon, so that along with the higher velocity probably accounts for the greater penetration.
Now lets bring back the extended magazine discussion! ;)