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

[Franko21]

I have been doing a lot of reading and have a couple of questions I am hopoing that people can chime in on:

Question 1 - How do you choose the right projectile weight? Is a 7mm RM shooting a 100 gr monolithic at 3500fps good for everything (deer, hogs, elk, etc.) or at some point do you need to step up to a heaver projectile?

Question 2 - If you do have to go to a heavier projectile what factors do you use to decide the right weight?

Question 3 - Does caliber matter? Is there going to be an appreciable difference in terminal performance between a 130 gr 6.5mm projectile going 3100 fps vs a .308 caliber 135gr projectile going 3100fps?

Thanks for reading this.

 

[FEENIX]

I have been doing a lot of reading and have a couple of questions I am hopoing that people can chime in on:

Question 1 - How do you choose the right projectile weight? Is a 7mm RM shooting a 100 gr monolithic at 3500fps good for everything (deer, hogs, elk, etc.) or at some point do you need to step up to a heaver projectile?

Question 2 - If you do have to go to a heavier projectile what factors do you use to decide the right weight?

Question 3 - Does caliber matter? Is there going to be an appreciable difference in terminal performance between a 130 gr 6.5mm projectile going 3100 fps vs a .308 caliber 135gr projectile going 3100fps?

Thanks for reading this.

Be prepared to get inundated.

 

[Chesterrose79]

I run TTSX in my 7mm rem mag. The way I chose was between 140gr, 150gr and 160gr. I actually put them both in my ballistic calculator to see which has the most energy at 600+ yards. I found the 150gr TTSX to be the sweet spot. It has more velocity than the 160gr and higher BC than the 140gr. I've managed to get them cooking at 3250fps.

I feel all will do well out to 600 but if I'm shooting at larger game I don't want to be under gunned to keep it ethical.

 

[mcdil]

Franko21,
As a formerly "heavy for caliber" Nosler Partition shooter myself, it can be difficult to understand how to choose a mono-metal bullet for your application. As a bullet manufacturer, mono-metal bullets at that, I can make that a bit easier, at least as it relates to the important criteria. From your questions above:
Question 1 Answer - For Apex Outdoors bullets, the simple answer is choose your projectile based on twist rate of your rifle. That simple. We list the weight of our bullets third. First is caliber followed by twist rate. That is the order of importance.
Question 2 Answer - Don't do this without the proper twist rate. Stay with the appropriate twist rate. This will always matter more than what you're perceiving the advantage of heavier would provide. Monos, at least properly designed ones, perform completely differently than a cup and core bullet.
Question 3 Answer - I'm always a big fan of displacement, but all of our Afterburner bullets, regardless of caliber, will perform much larger than what would normally be expected. Check out my recent post on a bear taken with our 30 cal 153gr bullet for terminal performance, etc.

Black Bear With the 153gr Afterburner - 523 Yards

We were excited to get a quick text and some pictures in this morning from yorke-1 who took this bear late last night on the west coast with our 153gr Afterburner out of a 300 RUM. I'm sure he'll come in at some point and add a bit more color to the story, but between a late night with the bear...

www.longrangehunting.com

 

[memtb]

Many people like to go lighter….much lighter with mono's. I much prefer to use normal cup & core weights to the lower end of normal weights and keep my shots within ranges to assure adequate expansion!

Again my opinion…..use the largest cartridge/caliber that you are comfortable with assuming comparable velocities! There is no substitution for cubic inches! memtb

 

[Hand Skills]

I have been doing a lot of reading and have a couple of questions I am hopoing that people can chime in on:

Question 1 - How do you choose the right projectile weight? Is a 7mm RM shooting a 100 gr monolithic at 3500fps good for everything (deer, hogs, elk, etc.) or at some point do you need to step up to a heaver projectile?

There are two main factors when it comes to killing things with bullets. The first often goes without saying, but SHOT PLACEMENT is number 1.

The second factor is BULLET PERFORMANCE, which has a tendency to get overstated and overthunk, but really comes down to 3 variables.

1. Bullet construction.

2. Impact velocity.

3. Target Resistance.

When it comes to bullet construction, MONOS are generally considered to be a harder bullet. Best terminal performance generally comes at high velocity.

Without getting too far off track, that 100gr 7mm bullet is going to shed velocity quickly. At some distance (depending on the atmospherics) it will be going too slowly to do a good job. Hunting bullet manufacturers typically state a 'minimum impact velocity for expansion'. When they include photos, you can clearly see that LESS IMPACT VELOCITY = LESS EXPANSION

So long as you use the bullet inside it's performance window and have enough velocity at impact, Take care of step #1 (shot placement), you're good to go.

Question 2 - If you do have to go to a heavier projectile what factors do you use to decide the right weight?

Usually it's other factors, like Ballistic Coefficient that lead me to heavier bullets.

Sometimes heavier bullets can offer better penetration on the terminal side of things, but with monos, penetration has never been a problem for me.

Question 3 - Does caliber matter? Is there going to be an appreciable difference in terminal performance between a 130 gr 6.5mm projectile going 3100 fps vs a .308 caliber 135gr projectile going 3100fps?

Thanks for reading this.

For sure there will be differences. If all bullets were created equal, we could have a discussion about it, but bullet construction varies a LOT, and that makes generalization difficult. Expanding bullets change their shape on impact, so without specifying a specific make and model of bullet, it's really hard to say.

In the case of NON EXPANDING SOLIDS, or FMJ's, we could probably make some generalizations, but that seems to be outside the scope of your particular application.

Anyway, I hope my responses help you on your quest!

 

[Laelkhunter]

I have heard and read that you should use a mono that weighs 10% less than your cup and core bullet. Worked out to be a 225 Barnes TTSX for my .340 Wby (I used to use 250 Partitions), and 168 Barnes TTSX in my 30/06. I used to use 180 in that. Both seemed to work fine, and accuracy was better than the Partitions. It's just a starting point, but make sure your barrel twist rate will handle the bullet you choose.

 

[Hand Skills]

I have heard and read that you should use a mono that weighs 10% less than your cup and core bullet. Worked out to be a 225 Barnes TTSX for my .340 Wby (I used to use 250 Partitions), and 168 Barnes TTSX in my 30/06. I used to use 180 in that. Both seemed to work fine, and accuracy was better than the Partitions. It's just a starting point, but make sure your barrel twist rate will handle the bullet you choose.

Not a bad rule of thumb, but if you go by density, it should be 15%.

Twist rate really throws a wrench into things though - LENGTH is the driving factor in gyroscopic stability, not weight. It actually comes down to the length of the bullet, but that is not a common specification, so most people just use a similar rule of thumb to what you suggest.

I think there are multiple reasons to use lighter for caliber monos, though.

Terminal performance just gets better and better the faster I shoot them!

 

[Petey308]

I have been doing a lot of reading and have a couple of questions I am hopoing that people can chime in on:

Question 1 - How do you choose the right projectile weight? Is a 7mm RM shooting a 100 gr monolithic at 3500fps good for everything (deer, hogs, elk, etc.) or at some point do you need to step up to a heaver projectile?

Question 2 - If you do have to go to a heavier projectile what factors do you use to decide the right weight?

Question 3 - Does caliber matter? Is there going to be an appreciable difference in terminal performance between a 130 gr 6.5mm projectile going 3100 fps vs a .308 caliber 135gr projectile going 3100fps?

Thanks for reading this.

That's a tough set of questions to answer outright, and FEENIX is right about becoming inundated lol. I'll do my me best to give my opinions based on my own experiences.

Question 1: How the particular mono is constructed and designed to behave/perform terminally makes a big difference on this one. Not all created equal. So I can't say any 100gr mono out of a 7mm RM would work for anything, but that's definitely light for caliber and is generally the right approach with monos.

Many traditional solid copper bullets do not shed weight and thus do not decrease their amount of sectional density as they travel through an animal. With those types of bullets, you oftentimes get too much penetration because they retain all their weight and sectional density. They over penetrate. Contrary to popular belief, that's not actually desirable. You only need that if you take shots like Texas heart shots, where you're asking the bullet to pass through the entire animal and guts to get to the vital organs.

Lead core bullets (as a comparison), and some newer mono design bullets, shed weight and reduce their sectional density as they penetrate and expand.

The softer/frangible lead core types, like Hornady ELDM, Sierra TMK, Bergers, etc work best when you start out with a high sectional density (heavy for caliber version). Because of that, they penetrate as needed from the start and then begin expanding, transferring massive amounts of hydrostatic and then hydraulic shock, then they shed weight as they experience all the resistance from the expansion and sudden impact. They then effectively lose sectional density as a result of shedding weight, so they continue to penetrate rather than experience shallow penetration (as a lighter version with less SD would experience), and they carry all the wounding into the vitals.

For best terminal performance, monos need to actually start out with LESS sectional density for best results because they lose less of it as they penetrate (or don't lose any at all). They don't shed as much weight. Most solids don't lose any weight at all and penetrate way too much.

All that said, there are a few mono options out there now that do shed weight and thus lose SD as they penetrate. Apex-Outdoors, Cutting Edge, Hammer, LeHigh Defense, etc are all good examples of such designs.

The thing with those designs is when the petals shed, you're left a lot of times with essentially just a caliber size shank left that's doing a majority of the rest of the wounding. That means it still needs a good deal of speed in order to produce enough rapid displacement of tissue/fluid (hydraulic force/shock). This is leads into question 2.

Question 2: The design of the mono really matters here, as does your twist rate and potential MV capabilities. I prefer not to be over a starting sectional density amount of .260 with a mono that doesn't shed weight.

Ideally, I don't really want to be over around .280 with one that is designed to shed its petals, but caliber size plays into this too. You can get by with more SD with some of the larger calibers due to them being larger and still producing a decent amount of hydraulic force as they penetrate deep. The smaller calibers seem to do a bit better being lighter so they as they shed weight and SD they keep up speed and thus still produce a good amount of hydraulic force.

I personally tend to view 30cal and up as "larger caliber" and 7mm and under as "smaller caliber" although I wouldn't generally call most 7mm cartridges small caliber, but for the purpose of segregating things for this, that's just where I put the line.

So with 7mm and below, and with a mono not designed to shed weight, pick a version with an SD no higher than right around .260. For a version that is designed to shed a significant amount of weight, like an Apex, Hammer, CE, etc, you can get by with up to around .300 with 7mm varieties. but again ideally .280 or less still, especially calibers under 7mm.

With 30cal and above, I still recommend no higher than .260 for those monos designed to retain all their weight, but .300 and even a bit more is typically okay with fast pushing cartridges with the types designed to shed a lot of weight. If it's a smaller cartridge like a 308w, I'd try to keep it no higher than .280 even with those that shed a lot of weight, just because impact velocity is going to be lower and thus potential hydraulic force will be lower too. Ideally, with cartridges like that, even .260 or lower will do better.

Question 3: This has kind of already been touched on with the previous two answers, but caliber size specifically, what you need to consider the most is potential wound channel size and what factors will affect that.

A smaller caliber like a 6mm can still work well with a lot of impact velocity so that it still produces a lot of rapid displacement of tissue/fluid (hydraulic force), but if it's not impacting very fast, wound channels tend to be very narrow. There's not much room for shot placement error in that scenario. So the cartridge being used, its MV capability, and the distance to the animal (impact velocity) matter the most here. With a mono that sheds its petals and is left with just a shank, you'd ideally want at least 1000ft-lbs of energy potential upon impact to produce sufficient hydraulic force. Keep in mind the bullet will release a lot of that energy as it sheds the petals. That said, the petals will indeed still produce their own wounding as they continue penetrating themselves. I haven't mentioned that until now, but it's definitely something I should have because they do indeed still inflict wounding themselves.

Larger calibers, even when left to just a shank, will inherently create wider wounding just from being wider alone compared to smaller calibers, plus the petals will be larger pieces than the smaller calibers.

So it really depends on things like which cartridges you have and the rifle. If the only 30cal you have is a 308w but you have a 264wm, you might be better of running a lighter but heavier bullet in the 264wm vs even a lighter bullet in the 308w.

You'd want to get a ballistic app and compare potential options in each cartridge and look at what each gives you as far as max range, drop, drift, energy, etc. and see which one shines more for your needs and with all the other factors I've mentioned.

So that's basically the best I can come up with off the top of my head right now. Again, it's hard to answer outright and I'm sure I'm missing some points and I'm sure others might have issues with some of what I've said. That's fine. Opinions differ and so do experiences. I'm giving you my advice based on my experience and opinions and I don't expect anyone to accept it as fact.

 

[Petey308]

As far as stability and twist rate, you ideally want a stability factor (SG) of at least 2.0 with monos due to them being less dense and longer weight for weight compared to lead core. An SG of 1.5 is sufficient with lead core, but in order to keep the center of pressure the proper distance from the center of gravity on the bullet in flight, you need that 2.0 for monos.

Under 2.0 with a mono, you lose out on some of the potential BC and under like 1.5 you're going to really start losing actual stability and accuracy at distance. Above 2.0 though any gain in BC or accuracy is very negligible.

 

[Franko21]

There are two main factors when it comes to killing things with bullets. The first often goes without saying, but SHOT PLACEMENT is number 1.

The second factor is BULLET PERFORMANCE, which has a tendency to get overstated and overthunk, but really comes down to 3 variables.

1. Bullet construction.

2. Impact velocity.

3. Target Resistance.

When it comes to bullet construction, MONOS are generally considered to be a harder bullet. Best terminal performance generally comes at high velocity.

Without getting too far off track, that 100gr 7mm bullet is going to shed velocity quickly. At some distance (depending on the atmospherics) it will be going too slowly to do a good job. Hunting bullet manufacturers typically state a 'minimum impact velocity for expansion'. When they include photos, you can clearly see that LESS IMPACT VELOCITY = LESS EXPANSION

So long as you use the bullet inside it's performance window and have enough velocity at impact, Take care of step #1 (shot placement), you're good to go.




Usually it's other factors, like Ballistic Coefficient that lead me to heavier bullets.

Sometimes heavier bullets can offer better penetration on the terminal side of things, but with monos, penetration has never been a problem for me.




For sure there will be differences. If all bullets were created equal, we could have a discussion about it, but bullet construction varies a LOT, and that makes generalization difficult. Expanding bullets change their shape on impact, so without specifying a specific make and model of bullet, it's really hard to say.

In the case of NON EXPANDING SOLIDS, or FMJ's, we could probably make some generalizations, but that seems to be outside the scope of your particular application.

Anyway, I hope my responses help you on your quest!

I suspected that drag coefficients might come into play but was wondering if there were other considerations as well.

Thank you.

 

[Franko21]

Not a bad rule of thumb, but if you go by density, it should be 15%.

Twist rate really throws a wrench into things though - LENGTH is the driving factor in gyroscopic stability, not weight. It actually comes down to the length of the bullet, but that is not a common specification, so most people just use a similar rule of thumb to what you suggest.

I think there are multiple reasons to use lighter for caliber monos, though.

Terminal performance just gets better and better the faster I shoot them!

Do you have any thoughts on caliber? For example do you think you get better performance from a lighter but faster 6.5 caliber projectile vs a slower but heavier 30 caliber projectile? (assuming that both are still going fast enough to function).

 

[Franko21]

That's a tough set of questions to answer outright, and FEENIX is right about becoming inundated lol. I'll do my me best to give my opinions based on my own experiences.

Question 1: How the particular mono is constructed and designed to behave/perform terminally makes a big difference on this one. Not all created equal. So I can't say any 100gr mono out of a 7mm RM would work for anything, but that's definitely light for caliber and is generally the right approach with monos.

Many traditional solid copper bullets do not shed weight and thus do not decrease their amount of sectional density as they travel through an animal. With those types of bullets, you oftentimes get too much penetration because they retain all their weight and sectional density. They over penetrate. Contrary to popular belief, that's not actually desirable. You only need that if you take shots like Texas heart shots, where you're asking the bullet to pass through the entire animal and guts to get to the vital organs.

Lead core bullets (as a comparison), and some newer mono design bullets, shed weight and reduce their sectional density as they penetrate and expand.

The softer/frangible lead core types, like Hornady ELDM, Sierra TMK, Bergers, etc work best when you start out with a high sectional density (heavy for caliber version). Because of that, they penetrate as needed from the start and then begin expanding, transferring massive amounts of hydrostatic and then hydraulic shock, then they shed weight as they experience all the resistance from the expansion and sudden impact. They then effectively lose sectional density as a result of shedding weight, so they continue to penetrate rather than experience shallow penetration (as a lighter version with less SD would experience), and they carry all the wounding into the vitals.

For best terminal performance, monos need to actually start out with LESS sectional density for best results because they lose less of it as they penetrate (or don't lose any at all). They don't shed as much weight. Most solids don't lose any weight at all and penetrate way too much.

All that said, there are a few mono options out there now that do shed weight and thus lose SD as they penetrate. Apex-Outdoors, Cutting Edge, Hammer, LeHigh Defense, etc are all good examples of such designs.

The thing with those designs is when the petals shed, you're left a lot of times with essentially just a caliber size shank left that's doing a majority of the rest of the wounding. That means it still needs a good deal of speed in order to produce enough rapid displacement of tissue/fluid (hydraulic force/shock). This is leads into question 2.

Question 2: The design of the mono really matters here, as does your twist rate and potential MV capabilities. I prefer not to be over a starting sectional density amount of .260 with a mono that doesn't shed weight.

Ideally, I don't really want to be over around .280 with one that is designed to shed its petals, but caliber size plays into this too. You can get by with more SD with some of the larger calibers due to them being larger and still producing a decent amount of hydraulic force as they penetrate deep. The smaller calibers seem to do a bit better being lighter so they as they shed weight and SD they keep up speed and thus still produce a good amount of hydraulic force.

I personally tend to view 30cal and up as "larger caliber" and 7mm and under as "smaller caliber" although I wouldn't generally call most 7mm cartridges small caliber, but for the purpose of segregating things for this, that's just where I put the line.

So with 7mm and below, and with a mono not designed to shed weight, pick a version with an SD no higher than right around .260. For a version that is designed to shed a significant amount of weight, like an Apex, Hammer, CE, etc, you can get by with up to around .300 with 7mm varieties. but again ideally .280 or less still, especially calibers under 7mm.

With 30cal and above, I still recommend no higher than .260 for those monos designed to retain all their weight, but .300 and even a bit more is typically okay with fast pushing cartridges with the types designed to shed a lot of weight. If it's a smaller cartridge like a 308w, I'd try to keep it no higher than .280 even with those that shed a lot of weight, just because impact velocity is going to be lower and thus potential hydraulic force will be lower too. Ideally, with cartridges like that, even .260 or lower will do better.

Question 3: This has kind of already been touched on with the previous two answers, but caliber size specifically, what you need to consider the most is potential wound channel size and what factors will affect that.

A smaller caliber like a 6mm can still work well with a lot of impact velocity so that it still produces a lot of rapid displacement of tissue/fluid (hydraulic force), but if it's not impacting very fast, wound channels tend to be very narrow. There's not much room for shot placement error in that scenario. So the cartridge being used, its MV capability, and the distance to the animal (impact velocity) matter the most here. With a mono that sheds its petals and is left with just a shank, you'd ideally want at least 1000ft-lbs of energy potential upon impact to produce sufficient hydraulic force. Keep in mind the bullet will release a lot of that energy as it sheds the petals. That said, the petals will indeed still produce their own wounding as they continue penetrating themselves. I haven't mentioned that until now, but it's definitely something I should have because they do indeed still inflict wounding themselves.

Larger calibers, even when left to just a shank, will inherently create wider wounding just from being wider alone compared to smaller calibers, plus the petals will be larger pieces than the smaller calibers.

So it really depends on things like which cartridges you have and the rifle. If the only 30cal you have is a 308w but you have a 264wm, you might be better of running a lighter but heavier bullet in the 264wm vs even a lighter bullet in the 308w.

You'd want to get a ballistic app and compare potential options in each cartridge and look at what each gives you as far as max range, drop, drift, energy, etc. and see which one shines more for your needs and with all the other factors I've mentioned.

So that's basically the best I can come up with off the top of my head right now. Again, it's hard to answer outright and I'm sure I'm missing some points and I'm sure others might have issues with some of what I've said. That's fine. Opinions differ and so do experiences. I'm giving you my advice based on my experience and opinions and I don't expect anyone to accept it as fact.

These answers get right to heart of what I was wondering about. It has given me a whole lot to think about in regard to penetration but also fragmentation. I understand that "more is always better" but recoil management is a real issue. I currently own a 7mm RM but have to constantly practice my recoil management skills. My brother is looking at getting a 6.5 PRC and in helping him do research it got me to thinking "I wonder if I could get similar terminal performance with less recoil".

Thank you for taking the time to help me out, it is greatly appreciated.

 

[Franko21]

Thanks to everyone so far, your responses have been great.