FWIW:
I like to use wetpack instead of water jugs to test hp's/penetration/expansion. Put 9" to 12" of newspapers together with duct tape & put the bundle in a cooler standing upright. I make enough bundles to fill the cooler & then I fill the cooler with water. The newspaper soaks the water up & becomes wetpack. Take the cooler to the range and pull a bundle out, set it up with a target stapled to it and test away. Each bundle is good for +/- 10 shots.
The hp's you tested are 11bhn which is kind of hard. I shoot similar designed hp's and try to use +/- 9bhn alloy. THese 125gr hp's were 9bhn with a 1050fps load.
Typically you want around 1bhn per 100fps with a cast/lead hp.
220gr cast hbwc's shot from a snubnosed 44spl/975fps (8bhn).
210gr hb hp swc shot from a snubnosed 44spl/1000fps (8bhn).
Made these swaged hp's for deer hunting.
It took several tries to get the alloy right so the bullets stayed intact for the velocity of 1100fps which simulated a 75yd to 100yd hit/velocity with a hot load. ended up using a +/- 11bhn alloy tested in wetpack @ 25yds.
The gt hp's you bought/tested are a great design, to bad they are 11bhn. The huge hp whole is correct for short bbl'd firearms. The 11bhn, not so much. Same bullet cast with different hp pins.
The penta hp's ='s 9bhn 800fps to 1000fps
The large round hp's ='s 10bhn 1000fps to 1200fps
The small round hp's ='s 12bhn 1200fps to 1400fps
Nevada ed is spot on, Id heat that lighter bullet up with a little more powder and re-test.