Copper Monos - How to choose the right weight(and maybe caliber)?

[Petey308]

The diameter is the diameter, once it changes SD changed and that bullet has to continue at that diameter UNLESS it sheds diameter, if SD can change with weight loss it will with diameter only it's a greater change.

Again, I get what you're saying, but only that front section increases in diameter, not the whole rest of the bullet, so it's not really the same unless it expands so much and there's so little left of the rest of the bullet that it has a cannonball-like appearance.

There's a lot of bullet left though still at caliber size diameter with these examples. They still have all their mass as well, which helps retain momentum. The wider frontal area will create more resistance though and slow it down more than it would with less diameter. So while its mass hasn't changed, it'll still lose velocity like it has lost mass.

This is how I see it anyways. I'll admit some more purposeful and specific testing could be useful to really prove these things one way or the other. I'm going off of what makes sense to me, and my own experience. I'm happy to be wrong and learn new things.

 

[bigngreen]

A 177 gr 7mm mono has an SD of .314, now let's blow of 60 gr and stay at cal diameter and we have a shank penetrating with an SD of .207, now same bullet but take it past it's ability to shed weight and just opens to .5 in and now we're at an SD of .101.
Now we have created a low SD bullet with a lot of momentum, thats when bullet start tumbling or turning, you see this quickly on elk, that's why I no longer load Barnes or Accubonds for elk!

 

[RockyMtnMT]

Again, I get what you're saying, but only that front section increases in diameter, not the whole rest of the bullet, so it's not really the same unless it expands so much and there's so little left of the rest of the bullet that it has a cannonball-like appearance.
View attachment 395632

There's a lot of bullet left though still at caliber size diameter with these examples. They still have all their mass as well, which helps retain momentum. The wider frontal area will create more resistance though and slow it down more than it would with less diameter. So while its mass hasn't changed, it'll still lose velocity like it has lost mass.

This is how I see it anyways. I'll admit some more purposeful and specific testing could be useful to really prove these things one way or the other. I'm going off of what makes sense to me, and my own experience. I'm happy to be wrong and learn new things.

There is a balance of retained shank length and retained rpm's that keeps the retained bullet traveling in a straight line. Yes momentum matters but it is lost rapidly during expansion. If there is no shedding of weight the forces to tumble become greater because the base is compelled to pass the large frontal area. This is why we would consider not shedding the nose to be nearly failure. It is better than not opening for sure, but really only about half way done. Looks pretty in pictures though. Along with the large frontal area creating force to tumble it also slows the velocity down too rapidly resulting in poor permanent wounding. Now combine that with a hard raking shot on ribs or shoulder bones and you are very likely to lose straight line penetration and possibly not get to vitals. If a bullet opens rapidly and sheds, leaving a flat frontal area, then momentum has a role in getting all the way through the animal maximizing permanent wounding. If a bullet is dependant on velocity dictating how much weight is retained then the effective range of velocity that the bullet will work effectively at is greatly reduced. Most materials are greatly effected by the velocity at impact. Lead blows up needing a jacket to try and contain it. Too much jacket performs poorly at low velocity. Too light a jacket can't handle high velocity close range impacts. Most typical copper looks like the photo you posted, also giving a narrow velocity window for good performance. Other coppers are too brittle and will tear too much and can't be controlled at low velocity resulting in a retained shank that comes to a newly pointed frontal area resulting in poor permanent wounding. This happens if the hollow point is to deep or shallow depending on the impact velocity. I know this because we tried these coppers. The copper we use in Hammers will retain the same weight at high velocity and low velocity. Bone or no bone with nearly the same frontal area.

Sectional density does play a role in terminal performance, just not in the way you describe. Higher sectional density bullets will deform more rapidly and completely at lower velocity. Basically they have more poop in their butt to drive the bullet through the expansion process.

 

[Trm82]

I'll throw my opinion in here !!
To me it's all about the distance you expect to shoot.
I'm like the rest of most guys on here. A new high Bc bullet is released and you have to try it , I love banging steel long range but for hunting where I live I don't believe I've ever shot a animal past 500 yards so for me I love lightning fast lazer beams usually Barnes ttsx/Lrx because for me I believe speed kills sometimes better than a high bc bullets inside 450-500 yards.
I love magnums and standard cartridges and light for caliber bullets ripping a**.
I would love to get on the Hammer train but supply is limited in Canada and the ones I do find I need to sell a kidney to afford to buy.

 

[Lou270]

Some wrong info here. Shoulder stabilization is what keeps bullets traveling "point first" in flesh. Twist has very little to do with it since flesh is 1000 times more dense than air. A pointed bullet that is "more stable" will travel point first a little further in flesh than a "less stable" bullet but it will still tumble. This is for ex why you may see something like a berger travel couple more inches before coming apart at long range.

The change of terminal shape of a hunting bullet is why it travels head on or why a blunt solid travels head on. Shoulder stabilization keeps them from flipping in general. Flat wrong to suggest an expanded front is more likely to tumble.

Here is video of shoulder stabilization. This is not controversial and been understood for a long time



Terminal sectional density is what drives penetration. The reason monos penetrate so deep is either they retain weight and have smaller frontal area (in case of barnes type) or blow off their petals and have a very small front and decent weight like a hammer. Both cases are likely to have a higher terminal SD than a lead/copper bullet that sheds weight and expands to wider frontal area even if
started with higher SD.

Lou

 

[JTH]

Lot's of info to digest here. Steve's info in particular is solid on how the hammer's perform. Just looking at your thread title alone, How to choose the right weight and caliber, here's the simple approach I'd suggest:

As others have suggested, first determine the maximum range you intend to shoot an animal.

Next, I'd suggest looking through the load data on the Hammer bullets load data thread on this site or on the Hammer forum. From this you can see a range of anticipated velocities with different weights and cartridges.

Find a few that look interesting and plug this data into a ballistics program like Shooter, Strelok, etc and compare wind drift at your max range.

To me the most challenging aspect of longer ranges is calling the wind correctly over the entire distance. it may be 15 mph where you are but virtually zero in the coulee the bull is bedded in. Less wind drift goes a long ways in making up for an error on the wind call.

Use the ballistic app and plug in a 10 mph wind at 90 degrees, write down and compare the drift in inches for different calibers and bullets at the velocities you find in the load data, at your realistic max range. This may help you zero in on the right bullet for your application.

I've loaded 124 gr 6.5 hammers at 3250 fps, 131 gr 7mm hammers at 3450 fps and 178 gr 30 cal hammers at 3280 fps. All shoot sub 1/2 moa and produced extremely impressive results on game. I can't say enough good things about them. I would also add that higher impact velocities produce unbelievable results but you have to understand the range is limited (likely 500-600 yards, possibly less) due to drift.

Be realistic about the range you need out of the bullet and then find the balance between anticipated velocity and wind drift. If you're 500 yards and in, you have a ton of options to choose from. Beyond that range, the field gets limited.

 

[Window]

Some wrong info here. Shoulder stabilization is what keeps bullets traveling "point first" in flesh. Twist has very little to do with it since flesh is 1000 times more dense than air. A pointed bullet that is "more stable" will travel point first a little further in flesh than a "less stable" bullet but it will still tumble. This is for ex why you may see something like a berger travel couple more inches before coming apart at long range.

The change of terminal shape of a hunting bullet is why it travels head on or why a blunt solid travels head on. Shoulder stabilization keeps them from flipping in general. Flat wrong to suggest an expanded front is more likely to tumble.

Here is video of shoulder stabilization. This is not controversial and been understood for a long time



Terminal sectional density is what drives penetration. The reason monos penetrate so deep is either they retain weight and have smaller frontal area (in case of barnes type) or blow off their petals and have a very small front and decent weight like a hammer. Both cases are likely to have a higher terminal SD than a lead/copper bullet that sheds weight and expands to wider frontal area even if
started with higher SD.

Lou

I believe there is definitely some merit to this logic especially with cup and core bullets. However, mono bullets when under spun are very likely to tumble, but when they are spun to spec or over spun the straight line penetration is nearly always the case even when impacting heavy bone. Years ago I shot a whitetail in Texas over a feeder at (if memory is correct) 200 yards with a 140 grain Nosler accubond out of a 270 mag on video. Deer was broadside and shot was in the crease behind the shoulder. The bullet after impact basically turned 90* and exited straight up through the spine. What would cause a bonded cup and core bonded bullet to do that? Could it have been the spin rate was marginal?

 

[FEENIX]

Some wrong info here. Shoulder stabilization is what keeps bullets traveling "point first" in flesh. Twist has very little to do with it since flesh is 1000 times more dense than air. A pointed bullet that is "more stable" will travel point first a little further in flesh than a "less stable" bullet but it will still tumble. This is for ex why you may see something like a berger travel couple more inches before coming apart at long range.

The change of terminal shape of a hunting bullet is why it travels head on or why a blunt solid travels head on. Shoulder stabilization keeps them from flipping in general. Flat wrong to suggest an expanded front is more likely to tumble.

Here is video of shoulder stabilization. This is not controversial and been understood for a long time



Terminal sectional density is what drives penetration. The reason monos penetrate so deep is either they retain weight and have smaller frontal area (in case of barnes type) or blow off their petals and have a very small front and decent weight like a hammer. Both cases are likely to have a higher terminal SD than a lead/copper bullet that sheds weight and expands to wider frontal area even if
started with higher SD.

Lou

GW did an excellent job explaining the SD. The video reinforces what @Petey308 is trying to point out. Thanks for sharing.

 

[RockyMtnMT]

Some wrong info here. Shoulder stabilization is what keeps bullets traveling "point first" in flesh. Twist has very little to do with it since flesh is 1000 times more dense than air. A pointed bullet that is "more stable" will travel point first a little further in flesh than a "less stable" bullet but it will still tumble. This is for ex why you may see something like a berger travel couple more inches before coming apart at long range.

The change of terminal shape of a hunting bullet is why it travels head on or why a blunt solid travels head on. Shoulder stabilization keeps them from flipping in general. Flat wrong to suggest an expanded front is more likely to tumble.

Here is video of shoulder stabilization. This is not controversial and been understood for a long time



Terminal sectional density is what drives penetration. The reason monos penetrate so deep is either they retain weight and have smaller frontal area (in case of barnes type) or blow off their petals and have a very small front and decent weight like a hammer. Both cases are likely to have a higher terminal SD than a lead/copper bullet that sheds weight and expands to wider frontal area even if
started with higher SD.

Lou

The only problem with that is the same bullet impacted at the same velocity with higher stability will penetrate farther before it tumbles. This proving that a higher rate of spin or more rpm's directly effects how straight and how far a projectile will penetrate.

I agree with the video claim that the deformed shape will effect bullet orientation as it passes through media.

 

[Lou270]

I believe there is definitely some merit to this logic especially with cup and core bullets. However, mono bullets when under spun are very likely to tumble, but when they are spun to spec or over spun the straight line penetration is nearly always the case even when impacting heavy bone. Years ago I shot a whitetail in Texas over a feeder at (if memory is correct) 200 yards with a 140 grain Nosler accubond out of a 270 mag on video. Deer was broadside and shot was in the crease behind the shoulder. The bullet after impact basically turned 90* and exited straight up through the spine. What would cause a bonded cup and core bonded bullet to do that? Could it have been the spin rate was marginal?

I believe there is definitely some merit to this logic especially with cup and core bullets. However, mono bullets when under spun are very likely to tumble, but when they are spun to spec or over spun the straight line penetration is nearly always the case even when impacting heavy bone. Years ago I shot a whitetail in Texas over a feeder at (if memory is correct) 200 yards with a 140 grain Nosler accubond out of a 270 mag on video. Deer was broadside and shot was in the crease behind the shoulder. The bullet after impact basically turned 90* and exited straight up through the spine. What would cause a bonded cup and core bonded bullet to do that? Could it have been the spin rate was marginal?

I would say uneven expansion is what would cause this to happen (i.e. bullet turning) unless your bullet was just keyholing to begin with. Some 270 wby have 1-12 twist which may not be sufficient for 140 AB. For ex, half the bullet contacted bone and caused significantly more expansion on one side of the bullet. Funny things can happen with penetration if do not have a uniform front and normally coincides with hitting bone, particularly heavy bone. However, game in general is not homogenous like ballistic gel so strange things can happen sometimes during the violent impact. This is one reason DG hunters want bullets that do no deform at all. In the case of a mono bullet if one of the petals comes off and others stay on could see some funny things happen in penetration. I don't think spin or stabilization would help much in this case.

Also monos that keep their petals have gaps in the frontal area between petals. Thinking on it more spin may not 'stabilize' the bullet in the traditional sense but present more frontal area across a given span of penetration since the bullet has a few more turns helping with shoulder stabilization. One theory anyway.

I would expect on something like the hammers if all the petals do not come off simultaneously could see some funny things happen as that may introduce instability that the shank does not recover from. The shank is essentially a wadcutter so should penetrate pretty straight unless some other forces causing it to tumble. In the case of the petal shedding mono more spin (RPM) would probably help with this particular scenario due to increased centrifugal force making sure petals come off quickly and uniformly as possible.

Lou

 

[Franko21]

From the discussion it appears that there are benefits to spinning a copper monolithic faster than the manufacturer's recommended minimum twist. If "overspin" is beneficial, once I burn out my current barrel, do I call up Bartlein and order the fastest twist they make in a 7mm? I understand that could limit my ability to shoot lighter cup and core bullets, but this is a single purpose gun anyways.

Once again, thanks to all who have contributed to this thread.

 

[Lou270]

The only problem with that is the same bullet impacted at the same velocity with higher stability will penetrate farther before it tumbles. This proving that a higher rate of spin or more rpm's directly effects how straight and how far a projectile will penetrate.

I agree with the video claim that the deformed shape will effect bullet orientation as it passes through media.

In the case of a 'hard nose' spitzer bullet this is correct. In the case of a bullet that is designed to deform by soft point (i.e. lead) the deformation starts pretty much right away. In the case of a hollow point the hollow point needs to fill up and push out sides but it is still very fast. Neither is inherent to tumble like a spitzer unless there is bad design. More twist/rpm may influence how a bullet deforms but whether this leads to more or straight penetration depends on things. For ex, if a bullet spins faster it may lose more weight due to centrifugal force flinging stuff off. This could cause the bullet to penetrate less due to less retained weight or wider front or it could cause the bullet to penetrate more if it leads to a more narrow frontal area. Depends on how the bullet is designed which is why we should follow what the bullet designer recommends and not assume more or less twist or velocity or whatever is 'always better'

Lou

 

[RockyMtnMT]

In the case of a 'hard nose' spitzer bullet this is correct. In the case of a bullet that is designed to deform by soft point (i.e. lead) the deformation starts pretty much right away. In the case of a hollow point the hollow point needs to fill up and push out sides but it is still very fast. Neither is inherent to tumble like a spitzer unless there is bad design. More twist/rpm may influence how a bullet deforms but whether this leads to more or straight penetration depends on things. For ex, if a bullet spins faster it may lose more weight due to centrifugal force flinging stuff off. This could cause the bullet to penetrate less due to less retained weight or wider front or it could cause the bullet to penetrate more if it leads to a more narrow frontal area. Depends on how the bullet is designed which is why we should follow what the bullet designer recommends and not assume more or less twist or velocity or whatever is 'always better'

Lou

We have proven this with deforming bullets that shed the nose. Rotational velocity is a significant contributor to length of penetration and straightness of penetration. Take it a step further to a bullet that is marginally stable for ballistic flight. A marginally stable bullet will fly very accurately consistently enough to compete in bench rest. This marginally stable bullet will likely have issues when impacting an animal. This where we see bullets do not expand at all. Plenty of impact vel for full expansion, so to say that stability plays no role in terminal performance is simply wrong. Or to say that it only matters for a non expanding spitzer is also wrong. No offence intended.

Another scenario that proves this it testing dangerous game solids. A shorter lighter solid that is designed not to lose any weight or expand will out penetrate a longer heavier one impacted at the same vel. Reason is that the longer shank will upset sooner and begin to tumble causing it to lose velocity sooner and penetrate less as well as going off track and changing direction. Give the longer heavier solid a higher rate of twist and it will improve the depth of penetration. The only time I would say that higher stability does not aid in straight line penetration is with a bullet has poor integrity and comes apart on impact. This really doesn't count, because bullets like this are bound for failure on tough animals or large animals requiring deep penetration. They are simply unpredictable.

While we are at it, let's blow up the theory that higher sectional density bullets will always have better penetration. I mentioned earlier that the amount of time that a bullet spends deforming and shedding weight will directly effect it's ability to penetrate. The longer this takes the more of the rotational vel and forward momentum is robbed. Let's take our 30 cal 124g Hammer Hunter with a sectional density of .187 will out penetrate other bullets of ours with much higher sectional density. Proven in media and lots of animals, big animals like water buffalo. @fordy was the first guy to take this little pill out and shoot animals way too big for it's weight. It outperforms .375 caliber bullets in it's penetration and stopping power. At this point I only have theories on how this can happen. According to conventional wisdom it can't, but it does. Not just once, but hundreds of times. I believe it comes down to a perfect balance of shed weight, length of retained shank, and form of retained shank that creates a pressure wave in front of the bullet as it passes through the soft tissue creating a scenario where very little material is actually touching the bullet. Along with that an incredibly high stability factor. Along the same lines, we have our 137g 30 cal Hammer Hunter. Designed proportionally the same as the 124g Hammer Hunter 30 cal. It was under performing to what we anticipated. Still outperforming conventional bullet, but not what we expected. We changed the hollow point depth by 2mm and gained 18" of penetration. Now it is running with the 124g Hammer Hunter, maybe slightly better. It has not had the chance yet to test on very many bovines and such. We will see after a proper number of animals are taken with it. One more. I am pretty sure that no one here would bet that a 248g .375 cal Hammer Hunter fired from a 10" twist rum would out penetrate a 281g Hammer Hunter fired from the same rifle. I lost that bet. Both bullets loose proportionally the same amount of weight on impact. As of right now the heavier higher sectional density bullet is overlooked by the Ausies when headed out to cull water buffalo. Sectional density of the two bullets is .252 and .285. Now, that same 375 rum has a new barrel with a 7" twist. I think this will make the 281g outperform the 248g. I'm not sure though. We will soon see. I used the 281g Hammer Hunter in Africa last April and flat decked everything I shot, including a giraffe. Shoulder shot he only made it 52y. That is like three jumps for a giraffe.

So, much of the information out there about bullet performance based on sectional density and energy was written by magazine writers back in the 50's and 60's and passed on as fact, simply does not stand up to scrutiny. Repeating it and stating it as fact without your own testing to back it up doesn't hold water. I don't claim to be an expert, or the smartest guy in the room, but I have set out to figure it out, in the process of producing the best bullet possible. We assumed a lot of stuff when we started making bullets, and when it didn't work, like we assumed, we set out to figure it out so we could correct it. Terminal performance in a hunting bullet is everything. Everything else is secondary.

 

[Calvin45]

We have proven this with deforming bullets that shed the nose. Rotational velocity is a significant contributor to length of penetration and straightness of penetration. Take it a step further to a bullet that is marginally stable for ballistic flight. A marginally stable bullet will fly very accurately consistently enough to compete in bench rest. This marginally stable bullet will likely have issues when impacting an animal. This where we see bullets do not expand at all. Plenty of impact vel for full expansion, so to say that stability plays no role in terminal performance is simply wrong. Or to say that it only matters for a non expanding spitzer is also wrong. No offence intended.

Another scenario that proves this it testing dangerous game solids. A shorter lighter solid that is designed not to lose any weight or expand will out penetrate a longer heavier one impacted at the same vel. Reason is that the longer shank will upset sooner and begin to tumble causing it to lose velocity sooner and penetrate less as well as going off track and changing direction. Give the longer heavier solid a higher rate of twist and it will improve the depth of penetration. The only time I would say that higher stability does not aid in straight line penetration is with a bullet has poor integrity and comes apart on impact. This really doesn't count, because bullets like this are bound for failure on tough animals or large animals requiring deep penetration. They are simply unpredictable.

While we are at it, let's blow up the theory that higher sectional density bullets will always have better penetration. I mentioned earlier that the amount of time that a bullet spends deforming and shedding weight will directly effect it's ability to penetrate. The longer this takes the more of the rotational vel and forward momentum is robbed. Let's take our 30 cal 124g Hammer Hunter with a sectional density of .187 will out penetrate other bullets of ours with much higher sectional density. Proven in media and lots of animals, big animals like water buffalo. @fordy was the first guy to take this little pill out and shoot animals way too big for it's weight. It outperforms .375 caliber bullets in it's penetration and stopping power. At this point I only have theories on how this can happen. According to conventional wisdom it can't, but it does. Not just once, but hundreds of times. I believe it comes down to a perfect balance of shed weight, length of retained shank, and form of retained shank that creates a pressure wave in front of the bullet as it passes through the soft tissue creating a scenario where very little material is actually touching the bullet. Along with that an incredibly high stability factor. Along the same lines, we have our 137g 30 cal Hammer Hunter. Designed proportionally the same as the 124g Hammer Hunter 30 cal. It was under performing to what we anticipated. Still outperforming conventional bullet, but not what we expected. We changed the hollow point depth by 2mm and gained 18" of penetration. Now it is running with the 124g Hammer Hunter, maybe slightly better. It has not had the chance yet to test on very many bovines and such. We will see after a proper number of animals are taken with it. One more. I am pretty sure that no one here would bet that a 248g .375 cal Hammer Hunter fired from a 10" twist rum would out penetrate a 281g Hammer Hunter fired from the same rifle. I lost that bet. Both bullets loose proportionally the same amount of weight on impact. As of right now the heavier higher sectional density bullet is overlooked by the Ausies when headed out to cull water buffalo. Sectional density of the two bullets is .252 and .285. Now, that same 375 rum has a new barrel with a 7" twist. I think this will make the 281g outperform the 248g. I'm not sure though. We will soon see. I used the 281g Hammer Hunter in Africa last April and flat decked everything I shot, including a giraffe. Shoulder shot he only made it 52y. That is like three jumps for a giraffe.

So, much of the information out there about bullet performance based on sectional density and energy was written by magazine writers back in the 50's and 60's and passed on as fact, simply does not stand up to scrutiny. Repeating it and stating it as fact without your own testing to back it up doesn't hold water. I don't claim to be an expert, or the smartest guy in the room, but I have set out to figure it out, in the process of producing the best bullet possible. We assumed a lot of stuff when we started making bullets, and when it didn't work, like we assumed, we set out to figure it out so we could correct it. Terminal performance in a hunting bullet is everything. Everything else is secondary.

This reminds me a bit of the myth of the "brush bullet" - that a heavy blunt bullet moving slower is less deflected by twigs and grass or other vegetation en route to the intended target. I forget where I read it but someone actually tested this theory and it holds no water whatsoever. A varmint bullet at 4K will straight up detonate on a twig but with big game bullets…just try to shoot the deer and not the tree haha!!!! They all deflect terribly!

Now I do believe, because i have seen with my own eyes, that really blunt profile bullets at close range just plain hit different (as do monos at warp speed or frangible heavy lead cores at distance - all work totally different in some ways but all work!) But that's the only reason (besides tube mags) they're any better for close range work in heavy brush…they don't magically go in a straighter line through a thicket!