January 04, 2011
Once upon a time, you got hollowpoint handgun ammo only if you handloaded cast bullets.
Imagine that! That sounds a little extreme in these days of broad bullet offerings, but as late as 1970, effective expanding bullets in a 100-count box were few and far between.
I confess to having a great fondness for cast bullets. Perhaps it comes from starting reloading when the selection of "ready-made" handgun bullets was limited, or maybe it was the performance I could achieve. I started buying cast bullets around the Dallas area and eventually found a small commercial caster who had hollowpoint molds and would let you specify the alloy he used.
One of the hollowpoint bullets I could buy ready to load was cast from an old Ideal #358429 hollowpoint mold--the classic .38 Special Elmer Keith design weighing around 155 grains in hollowpoint form. I bought several boxes and found the alloy I'd specified too soft to avoid leading in the .357 Magnum but was just right for .38 Spl. high-velocity speeds. I loaded up a bunch that gave 1,000 fps from an old 6-inch-barreled Colt New Service revolver I have.
Understand this was during a time when the Dallas Crime Lab's firearms caseload was modest. We were encouraged to experiment with anything gun or ammo related when we finished the day's casework. This was before we had gelatin at hand, but we had a vertical water tank for recovering fired bullets, and water could expand bullets nicely if they had the "right stuff."
The first tests with the cast Keith hollowpoints were disappointing. The nose either bulged or one side would break open. It was not pretty. Then the lack of expanding 9mm Luger ammo at the time triggered additional testing.
The Secret Special Load
A deputy sheriff dropped by the lab to show off a 9mm "secret special load" (his words) for his S&W Model 39. He loaded a cast hollowpoint bullet--the Ideal #356402 hollowpoint--but added a personal touch. He filled the cavity with antifreeze, plugged the opening with a piece of birdshot, and used model-airplane paint to hold things together. The deputy honestly had no idea that antifreeze was toxic; he was only seeking expansion and someone told him he needed antifreeze. We agreed to test a couple of rounds for him.
His mods allowed the bullet to expand with decent symmetry, but we were left with the question,
"Was it the pellet, the liquid, or both?" Inquiring minds had to know. Having plenty of the Keith bullets already loaded in .38 Spl., I started experimenting.
First, I duplicated his load, substituting water for the antifreeze and adding a pellet of #2 birdshot that was a friction fit in the cavity opening. The result was nice expansion. Then I used only the pellet, no liquid. Again, expansion looked great. The ball and/or the liquid seemed to equalize pressure on the cavity, making expansion more symmetrical. They also probably helped offset the negative effects of close-in bullet yaw, a major cause of asymmetrical bullet expansion.
To complete the series, we needed to eliminate the ball and try a liquid only, but this presented a problem. The water trap we used required the muzzle to point straight down; anything liquid in the cavity would run out long before we could yank the trigger. Then we had an "ah-hah!" moment: Use something that was solid at room temperature but would revert to a liquid under pressure. Paraffin.
We carefully dripped molten paraffin into a cavity, making sure we installed no air bubbles in the process. We gave the cartridges plenty of time to reach room temperature before testing. This worked too, and it was probably prettier expansion than the others.
An Easier Way
At this point, we had established that filling the cavity with "something" was going to make expansion more reliable and symmetrical. However, these techniques were time-consuming, requiring several minutes per cartridge to do correctly. Done incorrectly, they could affect accuracy and expansion or even produce a keyholing bullet. We moved on to the next step: improve expansion in the simplest, most time-effective manner.
We nailed this one on the first try. I used a scalpel blade and only light hand pressure to make four intersecting lines across the bullet nose, 45 degrees apart. This produced eight shallow notches surrounding the cavity. It took seconds, and the firing results were rather spectacular, considering how many factory bullets could not pull off such expansion at that point in ammunition evolution.
About Those Magnums
If you have enough velocity, you can overcome the limitations of primitive expanding bullet design. We didn't have too much trouble with getting .357 Mag. hollowpoint bullets--either cast or the early jacketed stuff--to expand as long as we had 4 inches of revolver barrel.
There was one magnum to consider with cast bullets, the .44 Magnum at mid-range velocities to reduce recoil. At that time, bullet-mold pins that formed the hollowpoint cavity were the same size for .38/.357 bullets as for larger ones. With a larger nose diameter, having the small pin meant the cavity walls for a .44-caliber bullet were much thicker. We loaded some .44-caliber Keith hollowpoints cast from a medium-soft alloy and set the load to produce about 1,050 fps from my ancient 4-inch S&W Model 29. With no modifications, the expansion was much like the .38 Spl. results; we could only bulge the nose. We were pretty sure the thick cavity walls would not benefit from the notching we applied to the .38 loads. Those walls had to come down.
Digging in my chest of gunsmith-ing tools, I found a 90-degree countersink bit. By hand, I reamed the cavity until the resulting bevel almost touched the outside diameter of the nose. The cavity now had a wide opening tapering to a small one that went deep. We called this a compound cavity, and you can still see this design today in modern handgun ammunition. I do not claim to have invented it; several people seem to have stumbled on to it independently. It allows initial expansion by thinning the leading edge, and it progressively slows the rate of expansion as rollback progresses. This helps resist loss of the nose portion at high velocity for higher retained weight.
The compound cavity was not as elegant a solution to the hobbyist as the simple notches that worked so well in the .38 Spl. First, reaming took off a fair bit of metal, changing the bullet weight. Second, it required care to avoid making a nonconcentric nose. And third, to avoid excessive weight variation, the reaming was best done after casting but before lubricating and loading. Done at a scale, a patient operator could ream and weigh until all the bullets were close to the same weight. Hey, it's the perfect thing to do in the middle of a January snowstorm when the wife i
s traveling, the power is out, and you can't open the door to shovel the walk. Tedious, yes, but it ensured effective expansion for the mid-range .44 Mag. load.
This type of tinkering-to-learn activity was a key part of our continued education at the lab but was never expected to yield any great social benefit or generate a bunch of patents. However, the hollowpoint tinkering helped a major ammo company get a significant new ammo line to work better nearly a decade after we had "played" with the cast bullets.
After we published the first ammo test program results (as I related in the July and August 2008 issues of Shooting Times), our lab turned into a popular stop for sales engineers working for ammo companies. One showed up with a new product line that was potentially a real upgrade in performance for many police cartridges. He had samples of 9x19mm Luger and .380 ACP plus a light-bullet .38 Spl. +P load that they thought would be the cat's meow in snubnosed revolvers.
We didn't inventory gelatin blocks, so we could not test while the sales guy was there. We scheduled block production to coincide with having several new cartridges to test, and I offered to include the ammo in our next round of formal testing. The sales guy was a little crestfallen, but I offered to shoot some preliminary screening shots into water while he was there. He agreed, and we shot all three samples into our trusty--and rusty--water tank to get some idea of the expansion potential.
The 9x19mm had enough velo- city to expand quite nicely, but the .38 Spl. and .380 ACP expanded either poorly or not at all from the short tubes of our test guns. With a look that said, "I don't understand," the engineer asked what I thought. I picked up a toolmakers' needle file and in less than 30 seconds had outfitted several of his samples with eight shallow nose notches each, just like we did to the old .38 cast bullets years before. Into the test tank they went.
I think you can guess the result: near-perfect expansion. Two weeks later we received new samples of the .380 ACP and .38 Spl., all sporting factory-created notches--eight to a bullet nose. We included them in the next round of testing, and they worked just right, thanks to a couple of curious "lab rats" who liked to play with cast bullets.