I've hunted with cast HP'd bullets for 40+ years. I have killed many deer, a few pigs and a few elk with them. I also have killed many varmints with HP'd cast bullets. I started in '68 with Lyman's 311041HP for the .308W and a 311410HP for the 30 Carbine. I still have the 311041HP which has also been an excellent hunting bullet in the 30-30, 30-06, 300 Savage, 308 CBC and several other .30 cal cartridges. The 311041HP also has been excellent in some .31 cals with groove diameter not over .311. I've used the 311041HP in all action types. I gave up on the 311410HP after several years and a lot of testing as, being a PB'd bullet, accuracy wasn't acceptable above 1600 fps.
It took several years testing and actual results to understand the necessity of having a correct balance of alloy, HP shape and depth of the HP for best terminal performance in game. With big game expansion with weight retention and not sloughing off the expansion petals was desired and gave the best terminal effect. In varmints maximum expansion with the nose petals blowing off inside the animal was best.....just like it's thin skinned jacketed bullet counter parts. While it wasn't rocket science it was a learning curve as there was no internet back then so progress was somewhat slower because information was not always readily available.
For big game I've found GC'd bullets cast of softer malleable alloys perform best. If velocities are 1150 - 1400 fps I use a 20-1 alloy, with 1400 - 1600 fps I use a 16-1 alloy. Maximum range for expansion is going to be dependent on the HP shape and depth. I have one HP pistol mould which is the Lyman 44 Devastator. Cast of 16-1 alloy weight retention is excellent with superb expansion. I use it in revolvers and a Contender. Other handgun bullets from .32 to .45 calibers are HP'd with the Forster HP 1/8" tool. The depth of the HP is dependent on what the bullet is to be used on. The HP can also be opened up easily with counter sinks for more rapid violent expansion. This has been very successful with the 313631, the 358156 and the 452490 in handguns when cast of 20-1 alloy (sometimes 30 or even 40-1 in the 32 S&WL, The 38 SPL and the 45 ACP. The only PB'd bullet I HP is for the 44 SPL (Skeeter's load) using a 44-250-K cast of 20-1. Here is the Devastator cast I use, and a 45 ACP HP'd with the 1/8" Forster then enhanced with a counter sink.
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For HP cast bullet use with velocities of 1600 - 2200+ fps I use a ternary alloy. I use COWWs +2% tin and then mixed 50/50 with pure lead. I usually AC the bullets. They are GC'd, and lubed with a soft lube such as Lar's 50/50 or 2500+ as cast. They are then sized in push through sizers if needed. That alloyed cast bullets can be pushed to 2200+ fps (in appropriate twist barrels) with excellent hunting accuracy (2 moa out to my max range of 200 yards) but the barrels must be cleaned every 8 rounds or so because fouling will accumulate and accuracy will get worse to about 4-5 moa. Using a clean barrel (or fouled with one or two shots) is not a problem when hunting because if I've not got the game in those 8 shots I might as well quit hunting and go to Burger King.......
With the 311316 (118 gr 32-20 GC'd) or the 313631 (105 gr SWC 32 GC'd H&R) bullets cast of COWWs + 2%tin, AC'd, HP'd with the 1/8" Forster 1/2 the length of the bullet and pushed at 1900 - 1950 fps out of the M1 carbine have proven deadly on coyote and lessor varmints. They would also be excellent for PD, especially in the shorter range urban/suburban environment.
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For use on game I have found bullets of 7mm up through .375 cast of the COWW + 2% tin & mixed 50/50 alloy HP'd with the Forster 1/8" to a depth of 3/16" and pushed at 2000 - 2200+ fps give optimal terminal performance on game. Here is an example of the 35-200-FN cast of that alloy, HP'd with the Forster and loaded to 2150 fps. The Texas 4 point (8 points to you easterners) weight about 150 on the hoof. You can see the terminal effect. Range was 90+ yards and he was essentially DRT staggering 15 - 20 yards sideways and going down. The 35 Rem with bullet before and after HPing. The deer, the exit outside, exit inside, entrance inside and entrance outside. That is very typical of the wounds with .30 through .35 caliber HP'd cast bullets as I use them.
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For the smaller deer the HP can be enhanced with a counter sink for improved terminal effect.
I consider the use of HP'd cast bullets to be specialty bullets which are used for hunting. I use the solid bullets for general shooting so multi cavity moulds w/o the HP pins work for me. HPing 50 - 100 of them with the Forster for the limited hunting use isn't that difficult.