This article appearing in Fouling Shot #203 of Jan/Feb 2010, was written by Ralph Schneider.
Back when I was first getting interested in hunting deer with cast bullets in the .45-70 cartridge, I thought that even those big slugs would be made more effective if I could persuade them to mushroom in the target. So I invested in a Lyman mold that came with a removable hollow point pin which produced a deep and rather nar-row cavity. The bullets looked great, but whenever I tried them out in an impact medium of some sort, the bullet nose would nearly always fragment and fall away, leav-ing the bullets stub to continue penetrating on its own; there was little mushrooming effect to speak of. Although some shooters have found this to be a useful ballistic outcome (see John Havilands excellent article in Handloader #260), I decided to continue looking for a combination that would produce genuine mushrooming with a cast bullet.
Since I have recently been impressed with the per-formance of cast pistol bullets with wide meplats and with the shallow point depression typified by Winchesters Dyna-Point .22 long rifle ammo, I decided to get a .45-70 bullet of the proper design and modify it with a very wide and shallow hollow point. I consulted with Veral Smith of LBT about the widest-nose bullet I could use in a Marlin 1895, and he recommended an LFN design.
Eventually the mold arrived: an LFN-459-410 GC mold that casts two bullets of near-perfect roundness and drops them from the mold with no need of any per-suasion. The meplat measures .330. Cast of my usual WW+ alloy (standard wheel weight alloy with 0.5% tin added; BHN 16), these bullets weigh 408 grains without the gas check or lube. I realize that a BHN of 16 seems a bit high for wheel weights, and it is slightly higher than I usually get from a batch of wheel weights (typically 13-15 BHN), but I checked them again and that is what they register.
Back when I was first getting interested in hunting deer with cast bullets in the .45-70 cartridge, I thought that even those big slugs would be made more effective if I could persuade them to mushroom in the target. So I invested in a Lyman mold that came with a removable hollow point pin which produced a deep and rather nar-row cavity. The bullets looked great, but whenever I tried them out in an impact medium of some sort, the bullet nose would nearly always fragment and fall away, leav-ing the bullets stub to continue penetrating on its own; there was little mushrooming effect to speak of. Although some shooters have found this to be a useful ballistic outcome (see John Havilands excellent article in Handloader #260), I decided to continue looking for a combination that would produce genuine mushrooming with a cast bullet.
Since I have recently been impressed with the per-formance of cast pistol bullets with wide meplats and with the shallow point depression typified by Winchesters Dyna-Point .22 long rifle ammo, I decided to get a .45-70 bullet of the proper design and modify it with a very wide and shallow hollow point. I consulted with Veral Smith of LBT about the widest-nose bullet I could use in a Marlin 1895, and he recommended an LFN design.
Eventually the mold arrived: an LFN-459-410 GC mold that casts two bullets of near-perfect roundness and drops them from the mold with no need of any per-suasion. The meplat measures .330. Cast of my usual WW+ alloy (standard wheel weight alloy with 0.5% tin added; BHN 16), these bullets weigh 408 grains without the gas check or lube. I realize that a BHN of 16 seems a bit high for wheel weights, and it is slightly higher than I usually get from a batch of wheel weights (typically 13-15 BHN), but I checked them again and that is what they register.
I selected a handful of these and proceeded to cre-ate DHP (Dished Hollow Point) bullets. I used a Forster hollow-point tool in a case trimmer to create a perfectly centered pilot hole in each bullet, then used just the point of a larger twist drill (turned by hand) to create the wide & shallow cavity, leaving just enough of the flat nose as a rim to support the bullet in the rifles magazine.
The cavities turned out to be .25 wide and about .05 deep-as near as the stem of my dial caliper could determine the depth. As an afterthought (a fortunate one, as it turned out), I also cast and prepared some bullets using the standard 20:1 (lead:tin) alloy, BHN 8.5; these bullets weighed an average of 406 grains each.
Load information is as follows: Starline cases, WLR primers, 50 grains H4895, bullets as described and sized to .459, lubed with LBT Blue Lube; OAL is 2.50. Muzzle velocity with the 417 grain bullets is 1725 f.p.s. The load is quite accurate, giving me 3 groups at 100 yards using either aperture sights or a Burris Fast Fire II red dot sight. Note that this load is appropriate for strong modern actions only.
Since I did not have a truckload of ballistic gelatin to use as a test medium, I opted for simplicity and used what I had: water-filled plastic gallon jugs lined up on a 2x10. (I make no assumption that this test medium is exactly like the body of a game animal; some parts of an animal are softer, such as the lungs; some are tougher, such as bones and sinew. But the water jugs did provide consistency and some indication of the behavior of the bullets in a medium somewhat akin to flesh. Remember that water is both incompressible and heavy.) The shooting was conducted at a distance of ten feet in order to improve the chance of accurate bullet impact and alignment with the jugs.
The test results that follow were initially a disappointment for someone who was hoping for good performance from painstaking hollow-pointing efforts. But the disappointment faded once I realized that the results were actually better than I had hoped for.
Test #1: DHP bullet, WW+ alloy. The bullet penetrat-ed more than 60 of water jugs. It showed very little mushrooming (to .520) and lost 81 grains of its weight (19%). Evidently, the shallowness of the HP cavity had not prevented the nose of the bullet from breaking away. The bullets probably mushroomed to a larger diameter in passing through the jugs, but because of the velocity and the alloy, the mushroomed metal broke off.
Test #2: DHP bullet, 20:1 alloy. The bullet penetrated 30 of water jugs and showed radical mushrooming (1.030 extreme, .910 average) and lost 14 grains of its weight (3%). Almost none of the nose had broken off, though the mushroom skirt showed a tear on one side. that probably indicated that some breakage was immi-nent. This is very good mushrooming performance.
Test #3: Flat nose bullet, WW+ alloy. The bullet pen-etrated 55 of water jugs and showed moderate but even mushrooming (.770 extreme, .710 average) and lost 19 grains of its weight (5%). Apparently very little of the nose had broken off; this bullet may provide a good balance of penetration and expansion-depending on the intended target.
Test #4: Flat nose bullet, 20:1 alloy. The bullet pene-trated slightly less than 30 of water jugs and showed radical and even mushrooming (.910 extreme, .900 average) and lost none of its original 406 gr. weight. For lighter or thin-skinned game that does not require deep penetration, this may be the best outcome of all.
Conclusions: unless a shooter wants bullet nose fragmentation, even a very shallow hollow point cavity may not produce desirable results; a wide flat nose does better, since it is somewhat less likely to break away on impact. And in order to achieve the greatest bullet expan-sion, or in order to balance bullet expansion with pene-tration, it is best to combine that flat nose with a proper bullet alloy. Bullets cast of softer alloys seem less likely to fragment on impact. But although a Brinell hardness number may be one indication of a bullets ability to expand without breakage, I do not doubt that there are other factors that enable the metal to deform without fracturing. Perhaps a CBA member with expertise in met-allurgy could help us here.
Certainly more data are needed in order to verify or modify the conclusions arrived at here. I would be inter-ested in hearing from other shooters and experimenters who have conducted their own experiments in cast bullet expansion; contact me at. And if you decide to use some element of the informal meth-ods described here, be sure to place the jugs in a per-fectly straight row (handle sides alternating), line up your shot carefully, and have a towel handy. Youre going to need it.
Load information is as follows: Starline cases, WLR primers, 50 grains H4895, bullets as described and sized to .459, lubed with LBT Blue Lube; OAL is 2.50. Muzzle velocity with the 417 grain bullets is 1725 f.p.s. The load is quite accurate, giving me 3 groups at 100 yards using either aperture sights or a Burris Fast Fire II red dot sight. Note that this load is appropriate for strong modern actions only.
Since I did not have a truckload of ballistic gelatin to use as a test medium, I opted for simplicity and used what I had: water-filled plastic gallon jugs lined up on a 2x10. (I make no assumption that this test medium is exactly like the body of a game animal; some parts of an animal are softer, such as the lungs; some are tougher, such as bones and sinew. But the water jugs did provide consistency and some indication of the behavior of the bullets in a medium somewhat akin to flesh. Remember that water is both incompressible and heavy.) The shooting was conducted at a distance of ten feet in order to improve the chance of accurate bullet impact and alignment with the jugs.
The test results that follow were initially a disappointment for someone who was hoping for good performance from painstaking hollow-pointing efforts. But the disappointment faded once I realized that the results were actually better than I had hoped for.
Test #1: DHP bullet, WW+ alloy. The bullet penetrat-ed more than 60 of water jugs. It showed very little mushrooming (to .520) and lost 81 grains of its weight (19%). Evidently, the shallowness of the HP cavity had not prevented the nose of the bullet from breaking away. The bullets probably mushroomed to a larger diameter in passing through the jugs, but because of the velocity and the alloy, the mushroomed metal broke off.
Test #2: DHP bullet, 20:1 alloy. The bullet penetrated 30 of water jugs and showed radical mushrooming (1.030 extreme, .910 average) and lost 14 grains of its weight (3%). Almost none of the nose had broken off, though the mushroom skirt showed a tear on one side. that probably indicated that some breakage was immi-nent. This is very good mushrooming performance.
Test #3: Flat nose bullet, WW+ alloy. The bullet pen-etrated 55 of water jugs and showed moderate but even mushrooming (.770 extreme, .710 average) and lost 19 grains of its weight (5%). Apparently very little of the nose had broken off; this bullet may provide a good balance of penetration and expansion-depending on the intended target.
Test #4: Flat nose bullet, 20:1 alloy. The bullet pene-trated slightly less than 30 of water jugs and showed radical and even mushrooming (.910 extreme, .900 average) and lost none of its original 406 gr. weight. For lighter or thin-skinned game that does not require deep penetration, this may be the best outcome of all.
Conclusions: unless a shooter wants bullet nose fragmentation, even a very shallow hollow point cavity may not produce desirable results; a wide flat nose does better, since it is somewhat less likely to break away on impact. And in order to achieve the greatest bullet expan-sion, or in order to balance bullet expansion with pene-tration, it is best to combine that flat nose with a proper bullet alloy. Bullets cast of softer alloys seem less likely to fragment on impact. But although a Brinell hardness number may be one indication of a bullets ability to expand without breakage, I do not doubt that there are other factors that enable the metal to deform without fracturing. Perhaps a CBA member with expertise in met-allurgy could help us here.
Certainly more data are needed in order to verify or modify the conclusions arrived at here. I would be inter-ested in hearing from other shooters and experimenters who have conducted their own experiments in cast bullet expansion; contact me at
