I was given some bismuth/tin alloy to cast into patched round ball and test as an alternative to lead here in CA. Here's my write-up and some pictures in case anybody else is looking for lead alternatives so they can hunt with PRB where lead is banned.
Home Cast Bismuth/Tin PRB 09/2021
Prior to this experiment, I had no experience with home casting of bullets or round ball of any kind. It took some trial and error as well as the helpful advice from a member of muzzleloadingforum.com. I used an electric hot plate, set on its highest setting, with a 2” threaded pipe fitting for a crucible and a large washer underneath. Given the time it would have taken for the bismuth alloy to melt, I helped things along by heating the crucible with a blowtorch. As the mixture warmed, I added pieces of the ingot until I was able to get a reasonably full bowl and used the ladle provided to move some of the apparent slag off to the side. I also used the blowtorch to heat the aluminum mold a little. As I got closer to casting, I set this mold on the electric hot plate to keep warming and set the ladle inside the melted alloy to warm as well.
Care was used to only fill one of the six cavities at a time. After I filled the cavities, I waited about 2-3 minutes for the balls to harden and cool slightly. The mold was opened over a bucket of water where the balls could drop in and be immediately quenched. Most of the balls would not drop free of the mold, as I expected. I lightly tapped the balls with the same hammer I used to cut the sprue in order to get them to drop free.
In all, I cast 42 balls from the 1-lb ingot. There was some left over in the crucible but it was getting a little harder to get a full ladle so I stopped casting at that point.
I weighed each ball on my digital grain scale and measured them with calipers. Most came in right around 140 grains. All measured 0.4825 in diameter from the 0.480 mold, showing about 5% expansion. I decided to sort them so that I would do accuracy tests on the balls that were within 1.5 grains of 140 and use the rest for penetration tests at a later date.
About a week later, I went out to a range to do accuracy testing & get some chronograph readings. Rather than running the accuracy and chronograph testing together, I did them separately. If this had been a more scientific test, I would have recorded each shot’s impact and velocity. But I really just wanted to get a general sense of how the balls behave. All shots were done from 50 yards, although I did a few at about 20 yards when shooting into a berm to see if I could recover the projectiles. The rifle being used is a Traditions Woodsman with a 1:48 twist. The rifle has open sights that are enhanced with fiberoptic lines for visibility. Time was about 8:00 am until noon and I was facing into the rising sun with enough visibility to see the target clearly, although the bullseye was difficult to see when looking at the front sight before each shot.
My first group was 3 shots with a patched .490 ball over 90 gr Pyrodex RS (FFG). The ball and patch combination is extremely tight. The patches are 0.018 thick and my barrel is about 0.501. Although it seats fairly easily with a range rod, it would is very difficult to seat the ball with the fiberglass rod attached to the rifle. The 3-shot group measured about 1.5”. This is typical for me in this combination and why I chose it as a starting load for comparison. A fourth shot was made through the chronograph and measured 1806 fps.
My next group was with the home cast Bismuth/Tin alloy balls, which measured .4825. In my previous experience with ITX round ball, which is very hard, I have had to use a thinner patch than what I use for lead. This thinner patch, measuring 0.01” thick, seated very easily – almost too easily. I used the same 90 grain load. The group was significantly larger at about 3” CTC but about the same height on the target. Velocity measured 1928 fps.
About this time, I had gone to check the targets when I realized that a fair amount of my patch material downrange was in pieces and heavily charred.
To try and tighten up the group, I went back to the thicker 0.018” patch that I was using for the lead balls and added a lubed felt wad over the powder charge. I backed off to 70 grains Pyrodex and tested accuracy again. The group measured around 2” and the velocity was 1611 fps.
Satisfied with this result, I wanted to get a comparison with a commercial alternative – ITX. With a 90 grain charge, the 155 grain ITX ball measured 1739 fps. I did not get a chronograph reading at 70 grains. I did run the accuracy test at 70 grains, however. The 3-shot group had two shots touching and one flyer down several inches, which was likely my shooting error.
To further test accuracy, I did a 5-shot group with the Bismuth alloy. The total group size was over 4”. However, there were two shots touching high and left of the bullseye, two shots centered around the bullseye and one down about 2” from the bullseye. Although the group size is larger, it is likely that my form is starting to break down and I am not quite lining up the sights the same from shot to shot – something I have noticed that I do sometimes when shooting open sights.
To further test the velocity baseline, I did some chronograph readings of the lead balls at 70 grains of powder. Those shots came in at 1618 and 1606 fps.
I was able to recover some of the projectiles in the dirt mound behind the target. The I recovered 2 ITX balls, 4 Bismuth alloy balls and a few fragments of these that had shattered. No lead balls were recovered. I am not sure if the balls had fragmented upon impact, leaving nothing to find or if I simply didn’t find any. The only lead fragments I could find were around the steel gong I had setup and took several shots at. The recovered ITX balls retained 100% of their weight and showed little if any deformation. Both measured at 0.487 in diameter before and after shooting. I am confident that I could reshoot these balls again with little to no change in the point of impact from a new, unfired ball. The Bismuth alloy balls that I recovered measured between 130.6 grains and 136.6 grains. Diameters were ever so slightly larger at 0.491, 0.488, 0.4995 and 0.486. For all practical purposes, I’d say there was no expansion but 92.9-97.1% weight retention. However, there were some balls that had shattered and only fragments were found. So terminal ballistic performance may vary significantly. This may be due to my own faulty casting methods that give some balls more strength than others. It may also have been from the balls hitting each other or rocks in the dirt.
I feel that the Bismuth alloy is a viable alternative to lead for roundball shooters who want to home cast. The alloy is easy to cast, accurate enough within the effective range of an open-sighted patched ball shooter and hard enough to give good penetration on medium-sized game while holding together. Better casting methods could yield a more consistent ball and using a scoped rifle could offer more reliable data that, I feel, may give better results from which to make comparisons. Velocity is nearly identical with the loads I was using, as was the point of impact. Though the bismuth alloy balls are lighter than lead, they were also easier to stuff down the barrel due to their smaller diameter. Further load and patch development could yield a combination that is as-accurate as lead and may have higher velocities. While lead is likely to offer some expansion on impact, it isn’t entirely necessary with a 50-caliber. The bismuth alloy’s hardness may help lethality by giving better chances of a pass-through on game than lead. Further testing on water jugs or ballistics gel would help get a better sense of its potential advantages or disadvantages on terminal performance. At about $0.40 per shot, the alloy offers the home caster a more cost-effective option.
However, ITX appears to be a superior product that showed better accuracy and tighter tolerances from the box I was using (all were within 1.1 grains of each other). It is also held together extremely well. So I would expect that it would achieve remarkable penetration. Expansion would probably be non-existent on game animals. But there are two main drawbacks to ITX that I can see. The first is the hardness. While it can aid penetration, I would hesitate to use ITX for hunting in areas where the terrain is very rocky. The lack of deformation may increase the odds of a bad ricochet, even after exiting an animal. The second is cost. ITX costs $1 each before shipping – over twice that of the bismuth alloy.
Home Cast Bismuth/Tin PRB 09/2021
Prior to this experiment, I had no experience with home casting of bullets or round ball of any kind. It took some trial and error as well as the helpful advice from a member of muzzleloadingforum.com. I used an electric hot plate, set on its highest setting, with a 2” threaded pipe fitting for a crucible and a large washer underneath. Given the time it would have taken for the bismuth alloy to melt, I helped things along by heating the crucible with a blowtorch. As the mixture warmed, I added pieces of the ingot until I was able to get a reasonably full bowl and used the ladle provided to move some of the apparent slag off to the side. I also used the blowtorch to heat the aluminum mold a little. As I got closer to casting, I set this mold on the electric hot plate to keep warming and set the ladle inside the melted alloy to warm as well.
Care was used to only fill one of the six cavities at a time. After I filled the cavities, I waited about 2-3 minutes for the balls to harden and cool slightly. The mold was opened over a bucket of water where the balls could drop in and be immediately quenched. Most of the balls would not drop free of the mold, as I expected. I lightly tapped the balls with the same hammer I used to cut the sprue in order to get them to drop free.
In all, I cast 42 balls from the 1-lb ingot. There was some left over in the crucible but it was getting a little harder to get a full ladle so I stopped casting at that point.
I weighed each ball on my digital grain scale and measured them with calipers. Most came in right around 140 grains. All measured 0.4825 in diameter from the 0.480 mold, showing about 5% expansion. I decided to sort them so that I would do accuracy tests on the balls that were within 1.5 grains of 140 and use the rest for penetration tests at a later date.
About a week later, I went out to a range to do accuracy testing & get some chronograph readings. Rather than running the accuracy and chronograph testing together, I did them separately. If this had been a more scientific test, I would have recorded each shot’s impact and velocity. But I really just wanted to get a general sense of how the balls behave. All shots were done from 50 yards, although I did a few at about 20 yards when shooting into a berm to see if I could recover the projectiles. The rifle being used is a Traditions Woodsman with a 1:48 twist. The rifle has open sights that are enhanced with fiberoptic lines for visibility. Time was about 8:00 am until noon and I was facing into the rising sun with enough visibility to see the target clearly, although the bullseye was difficult to see when looking at the front sight before each shot.
My first group was 3 shots with a patched .490 ball over 90 gr Pyrodex RS (FFG). The ball and patch combination is extremely tight. The patches are 0.018 thick and my barrel is about 0.501. Although it seats fairly easily with a range rod, it would is very difficult to seat the ball with the fiberglass rod attached to the rifle. The 3-shot group measured about 1.5”. This is typical for me in this combination and why I chose it as a starting load for comparison. A fourth shot was made through the chronograph and measured 1806 fps.
My next group was with the home cast Bismuth/Tin alloy balls, which measured .4825. In my previous experience with ITX round ball, which is very hard, I have had to use a thinner patch than what I use for lead. This thinner patch, measuring 0.01” thick, seated very easily – almost too easily. I used the same 90 grain load. The group was significantly larger at about 3” CTC but about the same height on the target. Velocity measured 1928 fps.
About this time, I had gone to check the targets when I realized that a fair amount of my patch material downrange was in pieces and heavily charred.
To try and tighten up the group, I went back to the thicker 0.018” patch that I was using for the lead balls and added a lubed felt wad over the powder charge. I backed off to 70 grains Pyrodex and tested accuracy again. The group measured around 2” and the velocity was 1611 fps.
Satisfied with this result, I wanted to get a comparison with a commercial alternative – ITX. With a 90 grain charge, the 155 grain ITX ball measured 1739 fps. I did not get a chronograph reading at 70 grains. I did run the accuracy test at 70 grains, however. The 3-shot group had two shots touching and one flyer down several inches, which was likely my shooting error.
To further test accuracy, I did a 5-shot group with the Bismuth alloy. The total group size was over 4”. However, there were two shots touching high and left of the bullseye, two shots centered around the bullseye and one down about 2” from the bullseye. Although the group size is larger, it is likely that my form is starting to break down and I am not quite lining up the sights the same from shot to shot – something I have noticed that I do sometimes when shooting open sights.
To further test the velocity baseline, I did some chronograph readings of the lead balls at 70 grains of powder. Those shots came in at 1618 and 1606 fps.
I was able to recover some of the projectiles in the dirt mound behind the target. The I recovered 2 ITX balls, 4 Bismuth alloy balls and a few fragments of these that had shattered. No lead balls were recovered. I am not sure if the balls had fragmented upon impact, leaving nothing to find or if I simply didn’t find any. The only lead fragments I could find were around the steel gong I had setup and took several shots at. The recovered ITX balls retained 100% of their weight and showed little if any deformation. Both measured at 0.487 in diameter before and after shooting. I am confident that I could reshoot these balls again with little to no change in the point of impact from a new, unfired ball. The Bismuth alloy balls that I recovered measured between 130.6 grains and 136.6 grains. Diameters were ever so slightly larger at 0.491, 0.488, 0.4995 and 0.486. For all practical purposes, I’d say there was no expansion but 92.9-97.1% weight retention. However, there were some balls that had shattered and only fragments were found. So terminal ballistic performance may vary significantly. This may be due to my own faulty casting methods that give some balls more strength than others. It may also have been from the balls hitting each other or rocks in the dirt.
I feel that the Bismuth alloy is a viable alternative to lead for roundball shooters who want to home cast. The alloy is easy to cast, accurate enough within the effective range of an open-sighted patched ball shooter and hard enough to give good penetration on medium-sized game while holding together. Better casting methods could yield a more consistent ball and using a scoped rifle could offer more reliable data that, I feel, may give better results from which to make comparisons. Velocity is nearly identical with the loads I was using, as was the point of impact. Though the bismuth alloy balls are lighter than lead, they were also easier to stuff down the barrel due to their smaller diameter. Further load and patch development could yield a combination that is as-accurate as lead and may have higher velocities. While lead is likely to offer some expansion on impact, it isn’t entirely necessary with a 50-caliber. The bismuth alloy’s hardness may help lethality by giving better chances of a pass-through on game than lead. Further testing on water jugs or ballistics gel would help get a better sense of its potential advantages or disadvantages on terminal performance. At about $0.40 per shot, the alloy offers the home caster a more cost-effective option.
However, ITX appears to be a superior product that showed better accuracy and tighter tolerances from the box I was using (all were within 1.1 grains of each other). It is also held together extremely well. So I would expect that it would achieve remarkable penetration. Expansion would probably be non-existent on game animals. But there are two main drawbacks to ITX that I can see. The first is the hardness. While it can aid penetration, I would hesitate to use ITX for hunting in areas where the terrain is very rocky. The lack of deformation may increase the odds of a bad ricochet, even after exiting an animal. The second is cost. ITX costs $1 each before shipping – over twice that of the bismuth alloy.