Big game copper bullet test PART 1

How would I get to do the test?

I had a great opportunity to conduct a test that had been on my mind for a while. It took me well over a year to make the necessary coordination and to get access to a test, and since Sako launched their own copper bullet this year, they were willing to let me use their testing range and equipment at Hausjärvi, Finland.

The opportunity presents itself after making a few calls and texts to the right person at Sako. My contact and I at Sako was speaking the same language after explaining to him about my idea in conducting this test.  I proposed to him that we would pick up few common copper bullets and make an honest and thorough test with them.
When we started the planning phase of the test I told him I had done some collaborating with Sako and the intent of this test is not to favor one manufacturer over the other and to be as honest of the result, no matter how the test come out. The immediate reply from Sako was “of course it needs to be honest and fair; otherwise it would not be a test at all”.

So I’m going to be honest with you guys, my shooting experiences is mainly  hunting and any hunting simulation, discipline and practices that is involved in hunting. I have never competed in any competitive shooting, whether it is F-Class or PRS style of tournament, my trigger time is spent on the range honing my shooting skills as should every responsible hunter should do, that’s as often as you possibly can. So the point in all of this is that you can understand these test result and take it as a information for hunters by a fellow hunter, so to speak.

Metsästäjä

Practice is the key to success if one wants to succeed.

Before we rush into the test and its results, I want to highlight one thing; whatever the results may be, it’s important to know that every hunter needs to understand their rifle and find the right cartridge for that specific rifle, since no barrel is identical every rifle will perform differently. If you have been shooting long enough you’ll understand that some cartridge will group better than others, it’s just a matter of finding what your rifle prefer in order to achieve tight accuracy to put down games as quickly as possible.

To Sako test range at Hausjärvi, Finland

owards the end of August 2020 was our Sako test range day at Hausjärvi Finland, we were ready to start the action. There were a few of us at the range; Lasse and Joija, from Sako Cartridges and Bruce form their marketing team. It’s great to know that Sako was also excited about doing this test as I was. Through my own social media accounts plugging in the events, Sako was also posting stories on their Instagram about what was happening at the range during this event. At this point I couldn’t resist the thought that they must really be confident in their new bullet, since they have the balls to update their social media before even one bullet was shot. What if their bullet fails? I asked them “What if Sako cartridges perform poorly during the day?” the answer was something I just must respect, “In that case we need to make better ones!

So, we decieded to pick six known cartridges/bullets and test the things we hunters always want to know..

“how accurate it is?”
“how does it work on different speeds?”
“how well the cartridge itself work”?
“how well does the bullet expand on hit”?
“how well will the bullet expand when shooting long range?”


We chose to use the following cartridges/bullets

1. SAKO POWERHEAD BLADE (10,5g)
2. SAKO POWERHEAD II / Barnes TTSX (10,9g)
3. LAPUA NATURALIS (11g)
4. TARVAS (10,7g)
5. NORMA ECOSTRIKE (9,7g)
6. HORNADY GMX (9,72g)

Just to clarify things a bit, all of the units are in European/metric measurements, so I suggest just to go on google search if you want to find out what gram is to grain or joules is to ft/lbs.

Which caliber?

We decided to use the .308WIN, purely because it’s the most sold caliber in Finland and if I recall correctly, it is also the most used caliber deer and larger games such as moose.

At first we thought that we would shoot all the cartridges with my own hunting rifle, but since later on we would be shooting them on gelatin blocks, we would need to calculate the speeds and reload the bullets to simulate the realistic distances. So we decided to use a suitable rifle with short barrel for such purpose. We chose another rifle, the Sako TRG M10 sniper rifle with 655mm barrel with 1:11 twist rate. 
If you are not familiar what the barrel twist rate or what it means I suggest you google it since I will be mentioning that quite a bit. A little info on the rifle, the TRG M10 is a very accurate rifle so no one can argue that we didn’t give all the cartridges a fair chance to perform well. Obviously there will be a debate on this matter, but leave a comment and we’ll talk more on that. My own experience with the TRG is limited to only a few times shooting up to 605m. I have a blog on that also, but unfortunately only in Finnish.You can find it here.

Let’s go then

Some small planning as we cleaned the gun to be prepared for the day. First, I would shoot all the bullets and we would measure the speeds at 10 meters and again at 100 meters. The computer will then measure the grouping and we get to compare the results. Kistler branded equipment was ready to receive and Lasse set up an empty sheet on the software and we were ready to send the first round downrange.

Lasse is feeding info into the software as I shoot the bullets


We shot a four round group just to warm up the barrel, and then I just started to shoot one bullet after another. We shot in five round sets and the equipment did the measuring, all the shots registered on the system. After we shot all the cartridges, we decided to clean the gun again and repeat the test once again. So we left the gun to get clean and headed to lunch.

The ones we selected


Next set

We started shooting again after lunch, this time it would be different, the rifle would be loaded so that I don’t know which bullet is in the chamber. We decided to do it this way so that there would be no particular reason for me shooting differently. You never know if you subconsciously try to perform better when you know you’re shooting someone’s bullet who is paying up for the costs of the range. So we wanted to avoid all of that. Well, Joija was reloading the magazine and I started shooting. At this point we were using the Sako TRG M10, 655mm barrel with 1:13″ twist rate and I was shooting at 100 meters distance.

So as she was loading the bullets to the TRG I just shot and shot, by the way, I love every moment of it. When all the five bullet sets were shot, the results were pretty much the same as they were before lunch. Two five round sets average looked like this:

1. SAKO POWERHEAD BLADE (10,5g/) 18,9mm
2. NORMA ECOSTRIKE (9,7g) 25,7mm
3. SAKO POWERHEAD II / Barnes TTSX (10,5g) 27,45mm
4.TARVAS (10,7g) 31,45mm
5. HORNADY GMX (9,72g) 32,55mm
6. LAPUA NATURALIS (11g) 37,35mm

About the results with the long barrel

At this point it seems only fair to say that very often the cartridges and bullets are barrel specific. That is the reason we wanted to offer the best and shoot the ammo with a TRG platform instead of my personal hunting rifle. So it also became pretty clear why I wanted to do another round the way we did it, so I would not know what bullet I’d be shooting at any time. Sako blade was that much better than the others… at least so far.

The purpose of this test is not to praise or favor any bullet over another. Everyone can make their own speculation and analyze the results as they wish. I am merely here to provide the facts. I can hardly wait for the results, we will be shooting the bullets into some ballistic gel and shoot some high speed (27 000fps) footage from it. So as fun as it is to shoot and test this ammo, those videos should be pretty interesting to watch. And all this will be visible to you too! We’ll talk more about it later; let’s go back to the results.

Above you will see the results of all bullets shot in group of five, and that was done twice, the result is the average of those two groups. As you can see, the Sako Powerhead Blade performed the best, but just by looking at each performance groups, all the bullets grouped well enough for hunting. When measuring the spread, you take the two furthest hits and measure the distance, from center to center. The largest group was a bit less than 40mm, but would still hit the ten point mark when shooting in “hunting shooting competition”. As the ten point marker has a 30mm diameter, all of the bullets would have broken the edge of it, since the distance from the furthest bullets when measured form the in-line of the hole would have been 73,35mm – 7,62mm = 29,73 so in that case it would hit the 30mm bullseye.

I want to point out that all the shots and groups are accurate enough for big game hunting. As a hunter, If I can achieved such groups, I can only imagine how much tighter it’ll group for the more proficient shooter who’s constantly shooting and doing tournament style competition . As I said, I’m doing this test as a fellow hunter to another hunter.

Short barrel test

The fact that all the bullets were shot for groupings and ballistic data, I still think it would not be enough for thorough results. As I said before, we will be shooting them to check expansion and control in ballistic gel. We want to examine how the bullet performs. For technical reasons, the gel blocks needs to be as close as 15 meters so we will need to find the right speed for the bullets to simulate the distances we want. The distances would be 50 meters, 100 meters and 200 meters.
Because of the reasons stated above, we decided to use a shorter barrel for the TGR to help reduce the velocity. The barrel twist rate will be change as well, since the bullets would fly a lot slower. So we chose a 355m long barrel that has a 1:8″ twist rate with a silencer.
With a short barrel, the length of the combustion chamber is a lot smaller than with a long barrel so obviously the speeds would be a lot slower. Usually all the bullets are tested with a 600mm barrel, but when you are out hunting you see a lot more hunters using shorter barrel rifles as it makes sense, especially for hunters who hunt and walk a lot in thick areas. With it, I think we should also measure the groups and not just the overall velocity of what we get or can achieve with a short barrel rifle.

When all the shots were taken, we noticed that almost all the speeds at 10 meters distance were almost identical in performance as if shot with a longer barrel at a distance of 90 meters. So we will not change anything on some ammo for our gelatin test. The last test and the longest  will be at 200m so the cartridges would be reloaded and shot later to make sure the speeds would add up to simulate the true distance. Lasse said that he could calculate the ballistic co-efficiency (BC) and load the bullets. I trust him since he is a professional, and the trust prove to be worth it (you will see this in the next part).

Sako TRG M10 355mm barrel

This short barrel test was executed the same way as the last one. I had no idea which cartridge I was using. I just concentrated on the shooting portion. When the test was over, we checked out the results, and two bullets stood out. One of them stood out a lot, so it was clear that I might have pull that one particular shot, error on my part, it happens. Again, I had no idea which cartridge I was using, since Joija was just loading the magazine and I do my part and focus on each shot to make sure I don’t mess up my shooting discipline or pull another shot. Below is the result.

1. SAKO POWERHEAD BLADE (10,5g) 15 + 23,1 = 19,05mm
2. SAKO POWERHEAD II / Barnes TTSX (10,9g) 31,8mm
3. TARVAS (10,7g) 42mm
4. NORMA ECOSTRIKE (9,7g) 44,1mm
5. HORNADY GMX (9,72g) 55,1mm
6. LAPUA NATURALIS (11g) 82,8 and 85,5 = 84,15mm

As you can notice above, even after the two cartridges were re-shot, we still saw a lot more spread. We started to wonder what might be the reason, as the biggest group was over 80mm and the smallest was less than 20mm, I should find at least some explanation for it. To be honest, at no point did I think something like this could happen with would be such a big difference. Anyway, what I think might have been the reason, (it could well be nonsense) but this is what I think happened:

One reason for the large group could be the tighter twist rate, as it might be that the bullet didn’t stabilize. When we are shooting at 100 meters distance, I find this hard to believe, and also because the effect was only on one bullet. Obviously huge reason for it is the short barrel, but why?

Short barrel of course has shorter length for pressure to work with, so there will be a lot of unignited material behind the bullet which will push it and make it wobble in the air, so the used gun powder plays a pig part on that. How the powder burns? If it burns fast, then the amount of the fully burned gunpowder will be more even, than if we use slow burning gun powder, as there will be more variation on the amount of the burnt powder. But when we look at the speeds of the Naturalis bullet (663,3ms | 664,8ms | 661,7ms | 662,4ms | 661ms) you can see, that it actually had pretty stable speeds so that might not be the reason for the large grouping after all. No matter how much I speculate, it seems I won’t figure it out. Let me know what you think.

None of the cartridges are meant to be used in such a short barrel, but surprisingly the Sako Blade -bullet performed excellent in this test. Based on only this test, it would be pretty easy to pick a bullet if it would to be used on a short barreled rifle…I wish was that easy.

At this point I find it mandatory to once more say that every rifle and its barrel is a unique piece of work, so no matter which cartridge you may choose, always go and test shoot the combo before using it in a real live hunting situation..

Speeds of the bullets

All the bullets were measured at 10 meters and again at 100 meters distance. As we did the measuring in two points, it allowed us to see how much the bullets drop and we could calculate the BC. I also dug up the speeds that the manufacturer input for their bullets so we can compare them. The purpose of this comes in to practice when doing some long range shooting using an app to calculate the trajectory of a bullet’s flight trajectory or when using a ballistic turret on your scope. Those turrets are nearly ALWAYS set up by the numbers you read from the side of your cartridge box. Not a lot of basic hunters even know what a gun chronograph is. You can agree or disagree on the matter, but just hold it for a while; there will be a comment section after this.

So, we are talking about a bullets external ballistics, also called bullet flight trajectory. If you are more interested in this topic I suggest you do google search, you will find plenty of info about the topic, such as how gravity, vortex and air resistance (drag) has an effect on trajectory as well as other deviations such as bullet design, weight and twist rates.


The thing I wanted to find out was to see how fast bullets lose their velocity and from that we could understand how much loss there is in the impact energy (J). So when you measure the speed in two points you can calculate how much it has lost speed and you can determine how much the speed drops when the distance increases. In this case the smaller the speed loss is, the better the bullet works for long distances.

Here are the numbers


Diagram: All test results are measured with Kistler measuring equipment using SAKO TRG M10 rifle, 655mm (25,7”) barrel.

There are two main things we can find out with the results we have.

1. How much you can actually trust the numbers that are on side of the cartridge box (all though some boxes had no info at all on that matter)

2. How well the bullet maintains its speed.

As everyone can see from the sheet above, there is actually only one bullet that had a significant loss of speed at that distance. Actually you might have been able to reason this just by looking at the shape of the bullet, since all the other bullets looks pretty aerodynamic, that one looks like, well there is a picture for you below, you can come up with your own metaphor.

All the participants from left to right:
SAKO POWERHEAD BLADE (10,5g)
SAKO POWERHEAD II / Barnes TTSX (10,9g)
LAPUA NATURALIS (11g)
TARVAS (10,7g)
NORMA ECOSTRIKE (9,7g)
HORNADY GMX (9,72g)

The biggest differences are the manufacturers claimed speed versus the actual speeds, and here I have a message to all manufacturers; please put all the needed info on the side / inside of the cartridge box, hunters have no time to google them, whenever they are necessary.

Well, back to the point.

As I said before, the importance of how reliable the info you get from the cartridge box can make a huge difference when hunting long range. An example from one of my previous hunt relying on the manufacturer’s load data was on a seal hunting trip with my brother, before the trip, we had been practicing a lot on the shooting range, shooting up to 300 meter with different winds so IF we get the chance to take a shot at a seal, it would be manageable. After a long day on the coast we spotted a seal from our boat on a small islet, there was another islet from where my brother could take the shot; it was exactly 250 meters from the seal. We left him on the islet, and he dialed his ballistic turret for 250m and suddenly remembered that when we were on a range he needed to take one more click to hit the bullseye.

So one more click, soft squeeze and BOOM, jackpot! He hit right where he was aiming. When you hunt seal on an islet, the shot must be perfect in order to drop the seal quick, otherwise it will dive back in the water and be gone. If the shot would have been two inches lower, it would have been a miss or in the worst case, hit the jaw.

Oops, that strain of thought took us on a memory lane there. Anyway, what I mean with this is that if on that seal hunting trip we would have blindly trusted the manufacturer’s info, we would have hit the metal plates on the shooting range.

Always keep in mind, that a responsible hunter never takes a long range shot on game, before he/she has tested how that particular cartridge works on their rifle!

Impact power of the bullets

There are certain laws that define what kind of bullets one can use when hunting different kind of game, I’m pretty sure all countries have their regulations, so I won’t dig in too deep in about regulations and policies. But I still want to mention that all the cartridges above have more than enough impact power at 100m distance, but what if we go further, and take long range shot? The energy of the impact can be easily calculated if you know the mass and speed of the bullet. Like this:

Energy (J) = speed^2 (m/s) * mass (kg) / 2

for example in case of the Hornady GMX it would look like this

810*810*0,00972 / 2 = 3188,64J


So, next time we will be shooting on the gelatin blocks to see what kind of impact our bullets make and how the bullets perform on expansion, as well as have it on a Slow-Motion video. Gelatin is basically equal to animals muscle tissue, and that is exactly what we want to see: how the bullets perform when hitting an animal. If we just wanted to see what kind of a “mushroom” the bullets make, we could have easily just shoot at a wet paper bundle. But that wouldn’t be as fun, would it!?

Part two, shooting the gelatin blocks, coming up…
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Further clarification

 got a lot of questions and feedback about the short barrel and the 1:8 twist rate, so here some info and justification for using it.

Our intention was, as mentioned before was to test for groups and measure the velocity, so we can add this all to the final report from the results of all bullets and its performance on the gelatin blocks.

Why the short 1:8″ twist rate

With 1:11 twist rate and 815ms speed the bullet spins 2916,96 rounds per second.
With 1:8 twist rate and 740ms speed it does 3600 rps.
With 1:8 twist rate and 650ms speed it does 3198,81 rps.

From those numbers we can see that the optimal twist rate would have been 1:9 but such test gun was not available.

he 1:8 twist rate short barrel rifle is Sako’s test rifle which is meant to simulate 300-500ms hits. With it, we got 2457 rounds per second at 500ms speed.

High speed camera also puts up some limitations. If the bullet would turn in the middle if the gelatin block, we would not get comparable data/videos so it is imperative that the bullets are stable enough.

So if we would have shot all the bullets with the long barrel, all the rps would have been a lot smaller which would not have been realistic to the distances we wanted to simulate (199m and 200m), but the bullets would have had a lot smaller rps. 

We had 38 psc of 40cm long blocks to use, so there wasn’t a lot of opportunity to re-shoot the bullets, and we wanted to be sure that the bullets wouldn’t fall inside the gelatin, so that we can take footage of the wound channel behavior.

For a short barreled rifle we can use more gun powder so there would be less empty space in the shell case and therefore much less of speed variation.


Diagram: The above chart measures the velocity, ballistic coefficient and the speed we would want vs. the speed we measured with reloaded cartridges

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