JugBusting 2 – 1,2 * Knockout Punch * revisited – controlling expansion
If you recall my last article, I had too much expansion of a HP due to the softness, due to the low BHN of the boolit metal I used. The Penta over-expanded and came right to the edge of losing its weight from the soft lead shearing off the edges of the mushroom.
This reminded me of a HP I worked on one summer that was to go into a .38 Special snub nose revolver that could make only 650 FPS with a Keith SWC HP. I don’t want to go off on a side road too far but…but, I had designed a way to open that HP with 3 separate big wings that would fold out wider than any normal HP in a 38 cal. pistol. No matter what lead blend I used those wings would break off as it entered a water pipe I tested in. The solution to that dilemma was to slow the opening, reduce just for a microsecond the hydraulic pressure on that cavity until that cast had entered the test media and slowed its speed a fraction allowing a little less hydraulic pressure acting on the cavity and opening the wings. I used caulking to fill the HP to accomplish this…pictured below is that HP.
Remembering this ‘initiator tip’, the caulked-in cavity, I decided to use the same principal to slow the development of that MP 452-200-HP Penta that over-expanded so badly.
The three casts pictured in the header above show how I caulked the cavities to form this initiator tip. Hornady does this with their FTX ‘Flex Tip Technology’ they employ in their Critical Defense Ammo. They claim it reduces the possibility of foreign material clogging the HP and making the HP act as a RNFP, further claiming that it reduces inconsistency in that projectile’s performance.
From my testing with the above mentioned Keith HP I determined that it sacrifices a little speed as the HP enters the test media and begins to slow as it meets resistance and reduces the hydraulic shock on the cavity as it opens. I thought I would try that with this over-performing Penta. A normal person would simply adjust their speed to accommodate this cast, or re-cast the HP with a wee lil harder boolit metal. Not being normal, and having an inquisitive mind, I decide to experiment in these subtleties of control instead.
Nothing has changed in the load, it is running at 891 FPS, but something has changed about the cast itself. If you remember, I stated in the last article that the HP’s were cast in April of 2018, and the BHN tested on cast day and the following day and again in Sept. of that same year. In Sept. they supposedly had settled in at a 7.1 BHN level. I retested them after the first jugbust and found that in that time from Sept of 2018 until now they had lost hardness down to a level of 6.9 BHN. This fact made me even more determined to see whether I could make that soft lead blend work properly.
I used 3 filler materials: hot glue, caulking, and paraffin. Pictured below left, top row is the hot glue initiator tips and below those a row of caulked cavities. The next picture is the paraffin wax.
I had intended to use the caulking in this jug test but overnight it had shrunk and there was no time to re-caulk and wait a day again for that to cure…introducing plan B, the paraffin wax. I believe that beeswax would make a fine ‘initiator tip’, but not having that to test with, I can’t chisel that in stone just yet. I believe that in the future one of our casters will find a superior material that will substitute and work to perfection. That material has to perform in the same manner, but it also has to remain in the HP cavity and resist heat and cold and physical damage that it would be subject to through rough handling. You will see this paraffin tested in the second video posted below.
The next video is testing the hot melt glue as an initiator tip. Although it is a fail in this application at low speed, it just may be a choice for faster magnum pistol or rifle speeds.
The recovered cast slowed enough coming out of the 4th jug that it did not destroy itself going into the metal backstop.
Pictured below is that recovered cast. Notice the ‘initiator tip’ still in place. The cast HP is flattened on both sides from having impacted the steel of the backstop as it ricocheted into the rear and then down into the lead catch bucket below the backstop.
I can confidently say that this hot melt glue is not the solution for this low speed cast HP, but it may be the best choice if your testing HP’s in a rifle, as in testing a HP that does perform well in say .45 Colt SAA revolver but when it’s shot at a couple hundred feet/second faster from your lever rifle it just frags or loses petals. Keep the hot melt ‘initiator tips’ in mind.
I believe that the material we use for the ‘initiator tip’, depending on its hardness and flexibility, will determine exactly how much attenuation it provides at various velocities. I believe also that we can make HP’s that did not work in either pistol or rifle more likely to perform properly. Our lead blends we cast with also determine whether a cast is likely to be ‘malleable’ or have a tendency to be ‘brittle’. If we are too far into either characteristic we will likely never be able to make an un-performing cast HP perform as desired…blending lead, tin, antimony, arsenic, and copper is an art form within itself.
As explained above, I had intended to use a softer tip on this next test, but having prepared those HP’s the day before the test, my caulking shrank and I didn’t want to lose another day getting this article ready for publication so I move on to plan B. I use paraffin instead.
This last video we had success; this is the paraffin ‘initiator tip’.
It is obvious in this next photo that the left ‘over-expanded’ cast does not have the height in profile that the cast on the right has. It came into the test media too fast while the right cast slowed for a microsecond or so, bled off speed, and expanded perfectly. The over-expanded cast is right on the verge of shedding petals, losing weight and penetration depth at the same time.
Notice how the petals of the right cast extend out perpendicular to the body of the HP; this is the maximum width of this cast HP design before they start to bend down towards the base. When this profile travels through the test media, whether it is a meat target or gel, it will travel through rotating to a stop and acting like a boat propeller cutting tissue and blood vessels.
Another look from the top shows the difference in diameter.
Well, that wraps this test up. We set out to attenuate the expansion and had a fail followed by a success. We prove that having the paraffin in that cavity acted in the same manner as the FTX insert used by Hornady. Should you have cast that you have determined are unusable in your carbine for instance, this experiment may have some merit in that it may help you to slow the expansion and make that cast HP useable in both your revolver or pistol and a rifle. Experimenting for yourself will tell very quickly if it is possible.
That’s a wrap on another one boys, hope you enjoyed it and that it may help you too, find that ‘sweet success’. Remember that we are all amateurs at this ‘casting & brass stuffing’ hobby regardless of time in grade. What one handloader discovers, regardless of its significance, may well be the little ‘tip or trick’ that helps another find success. I encourage you one and all to sign up at TRN to be authors and publish your videos and articles so that we may all learn together and keep this ole arcane hobby going for generations to come.
Have fun out there, be careful, keep that head on a swivel & watch that 6! . . . The times, they are a changing!
Born in 1950…HS grad, some college, no degrees, served in the US Marine Corps, educated there by the Navy in Electronics. Worked as an Electrician all my life and Contracted Heavy Industrial Control & Power Distribution for 20 years before retirement. Drive a black Chevy 4×4 and a Harley V-Rod. Married 40+ years, 3 great kids all 45 & older. Love my shop & do it all right there…