Hp pin "rule of thumb"

[altheating]

What is the "rule of thumb" when it comes to how far you extend the hollow point pin into the boolit when you set up to cast HP boolits? Do you set it to be bottomed out in the HP pin handle or adjust it out from the handle? What are your preferences?

[btroj]

Depends on many things. What caliber? What velocity? What alloy? Desired effect?
You need to balance these things to get the effect you desire. For varmint hunting a hard alloy, driven fast, with a big, deep hollow point will give good results. The same would be poor for big game hunting as it would give poor penetration.
With an adjustable pin you have the ability to test and see what works for you.

[Bass Ackward]

Also depends on what kind of accuracy you want and at what level you want that to occur too. You are setting the CofB back the deeper you go (removing more lead) which will affect things one way or another.

I generally like as shallow as possible as it is hard to keep the pin warm and mold good bullets the deeper you go.

Plus, if you are using a revolver and you undermine the front drive band, then will it be a drive band any longer? So if you have some misalignment, you will have to mold it hard like a rock which counters or removes options.

No free lunch. You have to play with it to know. :grin: (Isn't that a shame?) :grin:

[Mavrick]

I've only loaded for revolvers, mostly .41's, but I run the pin to the driving band. The pin is pointed, so the shank is even with the driving band. That's where I start.
I'm a little concerned about running it in much further with a PB boolit and getting the base to cave in(maybe get concave or puncture) That would be with a maximum-depth HP, tho'. I've run 'em pretty deep with a GC boolit, with no problem.
The molds I've had HPed were all SWC, one an RCBS, one a Lyman.
It's fun to be able to change things around a little.
Have fun,
Gene

[Larry Gibson]

There is not one set "rule of thumb" as such because it depends on what you're using the HP'd cast bullets for; Varmints or big game? Also depends on the velocity range of expected impact and of course, it depends on the alloy used.

The alloy used should be a malleable alloy that does not break of slough off the expansion petals easily. This generally means a pretty much pure lead bullet, binary alloys of lead/tin or lead/antimony or ternary alloys of lead/tin and a low amount of antimony. At muzzle velocities a 40-1 alloy or pure lead works well upwards of 1000 fps, 20-1 works well in the 1000 - 1300 fps range and 16 - 1 or 50/50 WW/lead works well upwards of 1400 - 2200+ fps. Accuracy with such alloys is primarily dependant on the design of the bullet, fit to the throat, PB or GC'd and the velocity pushed to.

With expected CF rifle cast bullet use at 1800 - 2500 fps use on varmints you'll want a very fast expanding or shattering bullet. Thus a wide deep HP is beneficial to and also aides in accuracy many times as Bass mentions. I like the depth of a standard Lyman HP pin or the 1/16" Forster HP drill to HP to below the driving band on bore riders and 2/3 the length of the bullet on Loverns.

On big game (deer, pigs, elk, etc.) with CF rifles using cast bullets in the 1800 - 2200+ fps range you want only enough HP to reliably aide quick expansion with minimal sloughing of petals. I've found that shortening the Lyman stems or using the 1/8" Forster drill to 1/3 the depth of the bullet nose on bore riders is about right with 50/50 alloy using velocities of 2100 - 2200 fps. Forster says to drill their HPs 1/8" and that may be a good "rule of thumb" as a starting place.

With magnum handgun (.357, .41 and .44s) loads with muzzle velocities of 1400+ fps I find a GC'd bullet with a softer 16-1 or 50/50 alloys to be the best for use with HPs. The 1/8" Forster drill to the depth of the bullet nose on a 358156 is excellent in the .357. The same 1/8 Forster drill to the depth of the bullet nose on a 410610 and opened to to a wide mouthed taper with a Michael’s QD stud drill is excellent in the .41 Magnum. The same can be done for the .44 Magnum with a 429244 but with the 429640 "Devastator" available that is the HP bullet of choice. All these bullets are GC'ed allowing excellent accuracy at true magnum velocities out of 6 - 7 1/2" barreled revolvers for hunting. These HP'd handgun bullets give excellent expansion and penetration on big game. I've yet to have one "blow up" on any animals shoulder as is often claimed by those who disparage HP bullet use. These same GC'd cast bullets when cast of pure lead or, preferably, 40-1 alloy are also excellent at 900 - 1050 fps. The 358156 HP'd with the Forster 1/8" drill at 150 - 1025 fps duplicates the "FBI" +p .38 Special load and gives better expansion.

I've been using HP'd cast bullets in handguns and rifles for 40+ years with excellent success. While I wouldn't hesitate to use a solid cast bullet for hunting the HP'd ones of proper alloy are always my first choice. They kill quicker is the reason. Now there are always exceptions to the above; one of my own is with a 257283HP mould I use for my Savage M23 25-20. It is a PB mould with the typical Lyman long HP pin that I cast the bullets out of 40-1. They are then double TL in LLA and loaded "as cast" to 1050 fps with 1 1/2 - 2" moa accuracy. As such they do very well on "red digger" squirrels I stalk and shoot in the Blue Mountains of NE Oregon.

All the above is about as close to a "rule of thumb" as I can get but it is best to tailor the HP to the bullet for the intended use rather than depend on a "one size fits all" HP application.

Larry Gibson

[btroj]

Larry is dead on. Tailor the bullet to the application.

[Ohio Rusty]

I like the pin deep enough that the tip is in line with the cannelure, or crimp groove. That makes a HP that is plenty deep that can expand easily.
Ohio Rusty ><>

[beagle]

I've always used the rule of thumb on HP cavity depth of 1/2 of the length of the bullet. The diameter rule of thumb is 1/3 of the diameter of the bullet rounded up to the next common drill size. Hollow base pins are 1/2 the diameter of the bullet and the heigth/depth is equal to the diameter of the hollow base pin. I sat down and measured a whole bunch of HP pins and cavities and HB pins and cavities and these rules have worked for me and run pretty close to what Lyman has used over the years based on the recorded measurements.

Of course, there are exceptions dependent on what the intended use is./beagle