Monomental and lead bullets compared

[Pheroze]

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4100882/#!po=4.02299

 

[Shootist43]

Pheroze, that was a long read. Sometimes a bit technical. I'm not too sure what it means for us as hunters. Especially when the possibility /eventuality of hitting bone is introduced into the mix. We all know that jacketed lead bullets and monometal(s) are capable of taking animals and that there are times when each are preferred over the other. I hope that we will always have the choice to use whichever one is most suited for the shot to be taken.

 

[CTDolan]

Lead-free will become law in pretty much all of the United States, and likely Europe, within 10 years, 20 at the most. There's a groundswell of pressure and every year more bills are brought forward. As for me, I've never used a lead-free projectile when hunting. Call me traditional but I prefer bullets with lead. Hopefully the option will always remain, but I doubt it.

 

[Bullthrower338]

Lead-free will become law in pretty much all of the United States, and likely Europe, within 10 years, 20 at the most. There's a groundswell of pressure and every year more bills are brought forward. As for me, I've never used a lead-free projectile when hunting. Call me traditional but I prefer bullets with lead. Hopefully the option will always remain, but I doubt it.

All the more reason to buy more bullets!

 

[Kawshik Rahman]

Pheroze
I read this one with a great deal of interest . During my career , only metal envelope bullets were available. However , on these forums l see that the new homogeneous metal bullets have largely replaced the metal envelope bullets of my time .
Based only on theory , l should think that the homogeneous metal bullet , being constructed from a single piece of metal , will hold together better than a metal envelope bullet when fired into the thick skinned animals . A prime example of this , is when a shooter attempts to reach the heart of a Gaur ( or buffalo ) by shooting through it's upper fore leg . I have seen many .375 Holland and Holland magnum calibre and .458 Winchester magnum calibre metal envelope bullets deform when taking this shot ; the metal envelope would some times rupture and the lead interior could be seen jutting out , when we would cut the beasts open for our clients and recover the bullets . Of course , modern ammunition manufacturing techniques have largely eliminated such problems in metal envelope ammunition ( hopefully ) . During my career , l have seen this with old ICI Kynoch ammunition , Winchester ammunition ( only for the .458 Winchester magnum calibre ) and Hornady ammunition .
However , l am speculating that homogeneous metal bullets can have certain undesirable features in certain calibres. We know that a homogeneous metal bullet will need to be longer than a metal envelope bullet , of the same weight ( for instance , a 500 grain homogeneous metal bullet will be longer than a 500 grain metal envelope bullet ) .
This means that the homogeneous metal bullet will occupy more room inside the cartridge case , thus leading to a reduction in powder charge . For cartridges like the .458 Winchester magnum calibre which already have a small cartridge case , as is , l can see this as being problematic . One way around the problem , would be to use lighter homogeneous metal bullets in calibres like the .458 Winchester magnum ( like using a 460 to 480 grain homogeneous metal bullets instead of a 500 grain homogeneous metal bullet ). However , penetration would surely be compromised. I speculate that users of the .458 Winchester magnum calibre will keep using the metal envelope bullet ( 500 grain weight ) for this reason .
At the same time , l wonder if the homogeneous metal bullet is more punishing on the rifling of the weapon than a traditional metal envelope bullet ?

 

[CoElkHunter]

Interesting article and thought provoking!

 

[grand veneur]

Is becoming more and more an obligation by law in many countries , especially in Europe.

But at the end it plays a subordinate role whether lead-free or lead-based bullets are used. A right shot placement will kill a game with or without lead. Sure , there are differences , but they are also present at the different varieties of lead-free or lead-based bullets because they are also very different in both groups.

A problem exists with the lead-free bullets in terms of accuracy , especially in older rifles. A caliber X is not always an exact caliber X , and that can be a problem , especially if these lead-free bullets are not a little bit under-calibrated and equipped with guiding grooves or banded. Classic lead-based bullets adapt better to caliber fluctuations , because they can press in better and deform better to adapt to the caliber of the barrel. The problematic is normally no longer present with modern barrels.

 

[CoElkHunter]

Pheroze
I read this one with a great deal of interest . During my career , only metal envelope bullets were available. However , on these forums l see that the new homogeneous metal bullets have largely replaced the metal envelope bullets of my time .
Based only on theory , l should think that the homogeneous metal bullet , being constructed from a single piece of metal , will hold together better than a metal envelope bullet when fired into the thick skinned animals . A prime example of this , is when a shooter attempts to reach the heart of a Gaur ( or buffalo ) by shooting through it's upper fore leg . I have seen many .375 Holland and Holland magnum calibre and .458 Winchester magnum calibre metal envelope bullets deform when taking this shot ; the metal envelope would some times rupture and the lead interior could be seen jutting out , when we would cut the beasts open for our clients and recover the bullets . Of course , modern ammunition manufacturing techniques have largely eliminated such problems in metal envelope ammunition ( hopefully ) . During my career , l have seen this with old ICI Kynoch ammunition , Winchester ammunition ( only for the .458 Winchester magnum calibre ) and Hornady ammunition .
However , l am speculating that homogeneous metal bullets can have certain undesirable features in certain calibres. We know that a homogeneous metal bullet will need to be longer than a metal envelope bullet , of the same weight ( for instance , a 500 grain homogeneous metal bullet will be longer than a 500 grain metal envelope bullet ) .
This means that the homogeneous metal bullet will occupy more room inside the cartridge case , thus leading to a reduction in powder charge . For cartridges like the .458 Winchester magnum calibre which already have a small cartridge case , as is , l can see this as being problematic . One way around the problem , would be to use lighter homogeneous metal bullets in calibres like the .458 Winchester magnum ( like using a 460 to 480 grain homogeneous metal bullets instead of a 500 grain homogeneous metal bullet ). However , penetration would surely be compromised. I speculate that users of the .458 Winchester magnum calibre will keep using the metal envelope bullet ( 500 grain weight ) for this reason .
At the same time , l wonder if the homogeneous metal bullet is more punishing on the rifling of the weapon than a traditional metal envelope bullet ?

Kawshik,
You make a great point with the monometal (homogenous) bullets being longer than the metal envelope bullets. I bought some Barnes 450 and 500gr bullets for my .458 WM. Haven’t loaded them yet, but they are LONG! But, I have some factory Barnes 450 and have seen factory 500gr Barnes, so I’ll have to figure out how Barnes compressed the powder to accommodate these longer bullets? I’m going to use W748 ball powder, so maybe it won’t be too much of an issue? Or maybe I should be looking for a .458 Lott? Ha! Ha!
CEH

 

[fourfive8]

Pheroze
I read this one with a great deal of interest . During my career , only metal envelope bullets were available. However , on these forums l see that the new homogeneous metal bullets have largely replaced the metal envelope bullets of my time .
Based only on theory , l should think that the homogeneous metal bullet , being constructed from a single piece of metal , will hold together better than a metal envelope bullet when fired into the thick skinned animals . A prime example of this , is when a shooter attempts to reach the heart of a Gaur ( or buffalo ) by shooting through it's upper fore leg . I have seen many .375 Holland and Holland magnum calibre and .458 Winchester magnum calibre metal envelope bullets deform when taking this shot ; the metal envelope would some times rupture and the lead interior could be seen jutting out , when we would cut the beasts open for our clients and recover the bullets . Of course , modern ammunition manufacturing techniques have largely eliminated such problems in metal envelope ammunition ( hopefully ) . During my career , l have seen this with old ICI Kynoch ammunition , Winchester ammunition ( only for the .458 Winchester magnum calibre ) and Hornady ammunition .
However , l am speculating that homogeneous metal bullets can have certain undesirable features in certain calibres. We know that a homogeneous metal bullet will need to be longer than a metal envelope bullet , of the same weight ( for instance , a 500 grain homogeneous metal bullet will be longer than a 500 grain metal envelope bullet ) .
This means that the homogeneous metal bullet will occupy more room inside the cartridge case , thus leading to a reduction in powder charge . For cartridges like the .458 Winchester magnum calibre which already have a small cartridge case , as is , l can see this as being problematic . One way around the problem , would be to use lighter homogeneous metal bullets in calibres like the .458 Winchester magnum ( like using a 460 to 480 grain homogeneous metal bullets instead of a 500 grain homogeneous metal bullet ). However , penetration would surely be compromised. I speculate that users of the .458 Winchester magnum calibre will keep using the metal envelope bullet ( 500 grain weight ) for this reason .
At the same time , l wonder if the homogeneous metal bullet is more punishing on the rifling of the weapon than a traditional metal envelope bullet ?

As to the linked study in the OP and a question as posed on another thread about low impact velocity of Barnes TSX (the Barnes failure thread). I had a little extra time one day to check on that. I set up my test wet pack media with imbedded hardwood (for bone simulation) and loaded a round to about 1300 fps. Specifically a 210 gr .338 Barnes TSX. Fired it into wet pack. The bullet acted just like a spire point FMJ as has been demo'd many times in the past. It did not open at all. It penetrated in a straight line for about 12" including the hardwood "bone" set at 4" from entry. At about the 12" mark it veered off axis (likely as it lost gyroscopic stability due to friction) at about 45 degrees yawing wildly- based on shape of track though the wet pack and ended up sideways at about 14" total penetration. That result matches very well with the CT scan images of the channel tracks in the linked study of the spire point monometal tests. No doubt that it would have been very effective on deer-sized to medium PG sized game but still not ideal as the erratic pathway would not be predictable for reaching vitals. Just for comparison- of all big game bullets- including bonded, expanding monometal and partitioned like Nosler Partitions and Swift AFs, that 12"+ penetration by that category of bullet at normal impact vels of 2000-2500 fps expected for normal hunting distances, is within the average. Very few of that category of bullet penetrate deeper than about 16" in that wet pack media. While similar mass and caliber bullets, at those same normal range impact velocities, like non-bonded Berger cup and cores, non-bonded Remington cup and cores and Hornady non-bonded cup and cores many times come apart and don't penetrate past about 8" or if they do stay together, shed significant mass with most not penetrating even to the 12" mark.

I believe the matter of bore wear and pressure have been largely resolved in the design of many of the monometal bullets with the drive band design. I have found no increase in pressure nor fouling with the copper monometals that have the drive band design. I have simply avoided the non-drive band (smooth sided) type monometals and have had zero issues. The surface area of a drive-banded monometal annealed copper bullet will have no more land contact surface area than a comparable smooth sided, conventional lead core jacketed bullet. So, simplistically, if bore pressure is comparable and contact surface area is comparable then there would be very little difference between the two designs in pressure and bore wear and fouling.

As to penetration.. a conventional lead core bullet no matter if bonded or not will begin shedding mass thus momentum as it penetrates thus reducing penetration potential as it penetrates. Typically a monometal expanding bullet will not shed much if any mass as it penetrates thus little to no loss of momentum/penetration potential as it penetrates. Also, the better bonded, lead core bullets shed less mass than the thin jacketed bonded lead core bullets. (As a side note, I've found that some of the bonded, thin jacketed lead core bullets are not much better than their non-bonded simple thin jacketed cup and core predecessors... having experienced failures on game with both types the old non-bonded and the newer bonded.) All in all, there is not much difference in potential penetration between a better bonded lead core bullet of a certain mass and its slightly less massive comparable counterpart monometal (as shown in the study). Examples could be something like: 500 grain bonded lead core expanding type at reasonable impact velocity compared to a 450 or 480 grain expanding type annealed copper monometal at similar impact velocity.

Caveat for all "one-of stories".... anecdotes may or may not have anything in common with valid statistics.

 

[CoElkHunter]

As to the linked study in the OP and a question as posed on another thread about low impact velocity of Barnes TSX (the Barnes failure thread). I had a little extra time one day to check on that. I set up my test wet pack media with imbedded hardwood (for bone simulation) and loaded a round to about 1300 fps. Specifically a 210 gr .338 Barnes TSX. Fired it into wet pack. The bullet acted just like a spire point FMJ as has been demo'd many times in the past. It did not open at all. It penetrated in a straight line for about 12" including the hardwood "bone" set at 4" from entry. At about the 12" mark it veered off axis (likely as it lost gyroscopic stability due to friction) at about 45 degrees yawing wildly- based on shape of track though the wet pack and ended up sideways at about 14" total penetration. That result matches very well with the CT scan images of the channel tracks in the linked study of the spire point monometal tests. No doubt that it would have been very effective on deer-sized to medium PG sized game but still not ideal as the erratic pathway would not be predictable for reaching vitals. Just for comparison- of all big game bullets- including bonded, expanding monometal and partitioned like Nosler Partitions and Swift AFs, that 12"+ penetration by that category of bullet at normal impact vels of 2000-2500 fps expected for normal hunting distances, is within the average. Very few of that category of bullet penetrate deeper than about 16" in that wet pack media. While similar mass and caliber bullets, at those same normal range impact velocities, like non-bonded Berger cup and cores, non-bonded Remington cup and cores and Hornady non-bonded cup and cores many times come apart and don't penetrate past about 8" or if they do stay together, shed significant mass with most not penetrating even to the 12" mark.

I believe the matter of bore wear and pressure have been largely resolved in the design of many of the monometal bullets with the drive band design. I have found no increase in pressure nor fouling with the copper monometals that have the drive band design. I have simply avoided the non-drive band (smooth sided) type monometals and have had zero issues. The surface area of a drive-banded monometal annealed copper bullet will have no more land contact surface area than a comparable smooth sided, conventional lead core jacketed bullet. So, simplistically, if bore pressure is comparable and contact surface area is comparable then there would be very little difference between the two designs in pressure and bore wear and fouling.

As to penetration.. a conventional lead core bullet no matter if bonded or not will begin shedding mass thus momentum as it penetrates thus reducing penetration potential as it penetrates. Typically a monometal expanding bullet will not shed much if any mass as it penetrates thus little to no loss of momentum/penetration potential as it penetrates. Also, the better bonded, lead core bullets shed less mass than the thin jacketed bonded lead core bullets. (As a side note, I've found that some of the bonded, thin jacketed lead core bullets are not much better than their non-bonded simple thin jacketed cup and core predecessors... having experienced failures on game with both types the old non-bonded and the newer bonded.) All in all, there is not much difference in potential penetration between a better bonded lead core bullet of a certain mass and its slightly less massive comparable counterpart monometal (as shown in the study). Examples could be something like: 500 grain bonded lead core expanding type at reasonable impact velocity compared to a 450 or 480 grain expanding type annealed copper monometal at similar impact velocity.

Caveat for all "one-of stories".... anecdotes may or may not have anything in common with valid statistics.

Very informative, real world hunting bullet penetration test and results!

 

[Kawshik Rahman]

Kawshik,
You make a great point with the monometal (homogenous) bullets being longer than the metal envelope bullets. I bought some Barnes 450 and 500gr bullets for my .458 WM. Haven’t loaded them yet, but they are LONG! But, I have some factory Barnes 450 and have seen factory 500gr Barnes, so I’ll have to figure out how Barnes compressed the powder to accommodate these longer bullets? I’m going to use W748 ball powder, so maybe it won’t be too much of an issue? Or maybe I should be looking for a .458 Lott? Ha! Ha!
CEH

Co Elk Hunter
I find your response most intriguing , especially about the 500 grain homogeneous bullets being used in your .458 Winchester magnum calibre rifles. I am curious about the actual velocity such a loading could accomplish due to the massive amount of powder room such a munition would occupy . Do remember to send me an update of your field use or tests , at your earliest convenience. I am most fascinated by it.
You will forgive me , as l have no experience with the .458 Lott cartridge.

 

[Kawshik Rahman]

As to the linked study in the OP and a question as posed on another thread about low impact velocity of Barnes TSX (the Barnes failure thread). I had a little extra time one day to check on that. I set up my test wet pack media with imbedded hardwood (for bone simulation) and loaded a round to about 1300 fps. Specifically a 210 gr .338 Barnes TSX. Fired it into wet pack. The bullet acted just like a spire point FMJ as has been demo'd many times in the past. It did not open at all. It penetrated in a straight line for about 12" including the hardwood "bone" set at 4" from entry. At about the 12" mark it veered off axis (likely as it lost gyroscopic stability due to friction) at about 45 degrees yawing wildly- based on shape of track though the wet pack and ended up sideways at about 14" total penetration. That result matches very well with the CT scan images of the channel tracks in the linked study of the spire point monometal tests. No doubt that it would have been very effective on deer-sized to medium PG sized game but still not ideal as the erratic pathway would not be predictable for reaching vitals. Just for comparison- of all big game bullets- including bonded, expanding monometal and partitioned like Nosler Partitions and Swift AFs, that 12"+ penetration by that category of bullet at normal impact vels of 2000-2500 fps expected for normal hunting distances, is within the average. Very few of that category of bullet penetrate deeper than about 16" in that wet pack media. While similar mass and caliber bullets, at those same normal range impact velocities, like non-bonded Berger cup and cores, non-bonded Remington cup and cores and Hornady non-bonded cup and cores many times come apart and don't penetrate past about 8" or if they do stay together, shed significant mass with most not penetrating even to the 12" mark.

I believe the matter of bore wear and pressure have been largely resolved in the design of many of the monometal bullets with the drive band design. I have found no increase in pressure nor fouling with the copper monometals that have the drive band design. I have simply avoided the non-drive band (smooth sided) type monometals and have had zero issues. The surface area of a drive-banded monometal annealed copper bullet will have no more land contact surface area than a comparable smooth sided, conventional lead core jacketed bullet. So, simplistically, if bore pressure is comparable and contact surface area is comparable then there would be very little difference between the two designs in pressure and bore wear and fouling.

As to penetration.. a conventional lead core bullet no matter if bonded or not will begin shedding mass thus momentum as it penetrates thus reducing penetration potential as it penetrates. Typically a monometal expanding bullet will not shed much if any mass as it penetrates thus little to no loss of momentum/penetration potential as it penetrates. Also, the better bonded, lead core bullets shed less mass than the thin jacketed bonded lead core bullets. (As a side note, I've found that some of the bonded, thin jacketed lead core bullets are not much better than their non-bonded simple thin jacketed cup and core predecessors... having experienced failures on game with both types the old non-bonded and the newer bonded.) All in all, there is not much difference in potential penetration between a better bonded lead core bullet of a certain mass and its slightly less massive comparable counterpart monometal (as shown in the study). Examples could be something like: 500 grain bonded lead core expanding type at reasonable impact velocity compared to a 450 or 480 grain expanding type annealed copper monometal at similar impact velocity.

Caveat for all "one-of stories".... anecdotes may or may not have anything in common with valid statistics.

Four five eight
Thank you so much for the technical , yet easy to understand reply. I read it with mixed feelings , as l slowly begin to realize that the metal envelope bullet of my time , will soon be completely replaced by the homogeneous metal bullet of today ( if it has not , already ) . Not completely , l hope.
I find it interesting that l was partially accurate in my speculation. From what l understand from your insightful response , there WAS initially a problem with homogeneous metal bullets being detrimental for rifle bores , which seems to fortunately have been rectified now.

 

[fourfive8]

Yes and some designs may still be detrimental to some guns- especially older ones. Early on I tried the original smooth sided Barnes X monometal. What a miserable design that was! Barnes even tried to mitigate the pressure and fouling issues of that bullet by applying a thick coating of some nature. Finally, after quite a few years of denial or sheer lethargy got serious and started using the well known design feature of the drive band and presto!

 

[Newboomer]

The thing that caught my attention was the fact that Barnes bullets have to be driven as fast as possible to achieve maximum performance. I had that thought and this confirms it. Being longer and lighter, monometal bullets require more case room, thereby requiring a hotter or faster powder to achieve the desired results from a smaller space.

 

[crs]

My thanks to the author, but this is old news that has been covered time and time again in the press and on forums.ever since monolithic bullets were introduced. I suppose that it will go on so long as new shooters enter the market and rediscover things.

Even I was part of a bullet testing team that tested bullets in Texas and then in Africa and published the results on Leverguns.com 12 + years ago. We did not shoot wet paper, water jugs, or layers of wood, but animals on Texas exotic ranches before the show went on the road to southern Africa.We did the project for fun and experience and shot ele, buff, leopard, and plains game (ho hum) back when all Barnes had was one Mono (we used NF and Punch with the cooperation and advice from the makers) so Barnes did not even make the cut.

We did shoot one non animal target; the 5/8 inch steel plate hanging pistol target on our range. Nothing even seriously dented the steel but North Fork FPS and the Punch which actually shot through it! Both of those were fired from a .45-70 at 50 yards distance. They also shot through frontal brain shots on ele later in Africa.

There are many good bullet choices in the more popular calibers for all shooters from target shooters to DG shooters .
All good that things keep improving.

 

[Ray B]

Several years back I tested a bunch of 30 cal bullets. At that time Barnes and a few small makers were the only ones involved with No-Lead bullets. while the Barnes did get massive penetration, the bullets of the day had a tendency to veer off course due apparently to the petals opening at different rates. I'm told that the bullets of recent manufacture are much more straight-line in penetration. I recall the "HT" bullet, made in Massachusetts was all copper alloy, had pressure relieving bands and a pointed nose that was hollowed had a very good showing. But I don't know what happened to the company- if it was bought out or what- Anyone know? the bullet was clearly well ahead of its time.

 

[cmk]

One thing I did not like about that study is that the lead bullet used for comparisons (Norma Vulkan) is a non-bonded cup and core bullet. Basically a bullet designed in the 1970's, with rapid expansion as a design feature. There has been a lot of development regarding bonding that would probably give slightly different results, if more modern bullets, e.g. Woodleighs, Norma Oryx or Swift A-frames had been used in the test.

Other than that, I can see the lead prohibition coming over the horizon, and maybe it's not a bad thing, considering that predators and birds will fare better without a leaded diet.

 

[Bob Nelson 35Whelen]

Pheroze
I read this one with a great deal of interest . During my career , only metal envelope bullets were available. However , on these forums l see that the new homogeneous metal bullets have largely replaced the metal envelope bullets of my time .
Based only on theory , l should think that the homogeneous metal bullet , being constructed from a single piece of metal , will hold together better than a metal envelope bullet when fired into the thick skinned animals . A prime example of this , is when a shooter attempts to reach the heart of a Gaur ( or buffalo ) by shooting through it's upper fore leg . I have seen many .375 Holland and Holland magnum calibre and .458 Winchester magnum calibre metal envelope bullets deform when taking this shot ; the metal envelope would some times rupture and the lead interior could be seen jutting out , when we would cut the beasts open for our clients and recover the bullets . Of course , modern ammunition manufacturing techniques have largely eliminated such problems in metal envelope ammunition ( hopefully ) . During my career , l have seen this with old ICI Kynoch ammunition , Winchester ammunition ( only for the .458 Winchester magnum calibre ) and Hornady ammunition .
However , l am speculating that homogeneous metal bullets can have certain undesirable features in certain calibres. We know that a homogeneous metal bullet will need to be longer than a metal envelope bullet , of the same weight ( for instance , a 500 grain homogeneous metal bullet will be longer than a 500 grain metal envelope bullet ) .
This means that the homogeneous metal bullet will occupy more room inside the cartridge case , thus leading to a reduction in powder charge . For cartridges like the .458 Winchester magnum calibre which already have a small cartridge case , as is , l can see this as being problematic . One way around the problem , would be to use lighter homogeneous metal bullets in calibres like the .458 Winchester magnum ( like using a 460 to 480 grain homogeneous metal bullets instead of a 500 grain homogeneous metal bullet ). However , penetration would surely be compromised. I speculate that users of the .458 Winchester magnum calibre will keep using the metal envelope bullet ( 500 grain weight ) for this reason .
At the same time , l wonder if the homogeneous metal bullet is more punishing on the rifling of the weapon than a traditional metal envelope bullet ?

Kawshick Rahman
Dear,friend of Ponton
In reply to momometal/ homogeneous bullets woodleigh in Australia make a bullet our of lathe turned brass called the hydrostatic shock. It is light for caliber but even in the humble 30/30 Winchester will almost punch completely thru one of our Australian water buffalo. In the larger magnum cartridges it has been known to completely penetrate an elephants skull side to side. A friend of mine shot a buffalo front on with a 300 Weatherby magnum and the bullet traversed the complete length of the animal kicking up dust a long way behind it. The animal took a fermented steps and fell over. The internal damage was massive. To find out more you can look up Woodleigh bullets.
Cheers Sgt
Bob Nelson

 

[Bob Nelson 35Whelen]

As to the linked study in the OP and a question as posed on another thread about low impact velocity of Barnes TSX (the Barnes failure thread). I had a little extra time one day to check on that. I set up my test wet pack media with imbedded hardwood (for bone simulation) and loaded a round to about 1300 fps. Specifically a 210 gr .338 Barnes TSX. Fired it into wet pack. The bullet acted just like a spire point FMJ as has been demo'd many times in the past. It did not open at all. It penetrated in a straight line for about 12" including the hardwood "bone" set at 4" from entry. At about the 12" mark it veered off axis (likely as it lost gyroscopic stability due to friction) at about 45 degrees yawing wildly- based on shape of track though the wet pack and ended up sideways at about 14" total penetration. That result matches very well with the CT scan images of the channel tracks in the linked study of the spire point monometal tests. No doubt that it would have been very effective on deer-sized to medium PG sized game but still not ideal as the erratic pathway would not be predictable for reaching vitals. Just for comparison- of all big game bullets- including bonded, expanding monometal and partitioned like Nosler Partitions and Swift AFs, that 12"+ penetration by that category of bullet at normal impact vels of 2000-2500 fps expected for normal hunting distances, is within the average. Very few of that category of bullet penetrate deeper than about 16" in that wet pack media. While similar mass and caliber bullets, at those same normal range impact velocities, like non-bonded Berger cup and cores, non-bonded Remington cup and cores and Hornady non-bonded cup and cores many times come apart and don't penetrate past about 8" or if they do stay together, shed significant mass with most not penetrating even to the 12" mark.

I believe the matter of bore wear and pressure have been largely resolved in the design of many of the monometal bullets with the drive band design. I have found no increase in pressure nor fouling with the copper monometals that have the drive band design. I have simply avoided the non-drive band (smooth sided) type monometals and have had zero issues. The surface area of a drive-banded monometal annealed copper bullet will have no more land contact surface area than a comparable smooth sided, conventional lead core jacketed bullet. So, simplistically, if bore pressure is comparable and contact surface area is comparable then there would be very little difference between the two designs in pressure and bore wear and fouling.

As to penetration.. a conventional lead core bullet no matter if bonded or not will begin shedding mass thus momentum as it penetrates thus reducing penetration potential as it penetrates. Typically a monometal expanding bullet will not shed much if any mass as it penetrates thus little to no loss of momentum/penetration potential as it penetrates. Also, the better bonded, lead core bullets shed less mass than the thin jacketed bonded lead core bullets. (As a side note, I've found that some of the bonded, thin jacketed lead core bullets are not much better than their non-bonded simple thin jacketed cup and core predecessors... having experienced failures on game with both types the old non-bonded and the newer bonded.) All in all, there is not much difference in potential penetration between a better bonded lead core bullet of a certain mass and its slightly less massive comparable counterpart monometal (as shown in the study). Examples could be something like: 500 grain bonded lead core expanding type at reasonable impact velocity compared to a 450 or 480 grain expanding type annealed copper monometal at similar impact velocity.

Caveat for all "one-of stories".... anecdotes may or may not have anything in common with valid statistics.

fourfive8
Very well explained and interesting experiments.

 

[samu]

More study conducted in Sweden with 6.5x55 https://jagareforbundet.se/contentassets/7099893fd13b45b98e1900d2ea165fee/65x55_se.pdf
Bottom line, 7.8g copper performs on par with old classic 10.1g Oryx. Lapua mega was profen as crappy bullet which most of us knew already.