Improving the 308 Win performance

[akmtnhnt]

Okay then provide the software and the data on the bullet.

It's GRT. You just get a lot of MV data and use the OBT tool to adjust Ba and K. From data other people with the pressure trace II have shared on discord, if you have a lot of different charge data points for the exact same everything else, you can model the powder close enough to what they're getting with the pressure trace.
It might only be 72kpsi, but we're not talking the bleeding edge of overpressure for the 308 splitting hairs. We're talking 15kpsi high. Sure, small rifle primer brass, magnum primers and it only lasts 2 loads, the rifle isn't going to blow up nor will the brass split, might not even show all that many signs depending on the rifle itself.

 

[xsn10s]

I'm not familiar with that software. So do you have the case with that 52 gr load and bullet? How did you measure the bullet dimensions for the data imput? Did you use a micrometer, an optical compartor, or some other tool? Links for the softer/ equipment or pics of your findings would help. Still sounds like just a guess. It's not using actual pressure monitoring equipment.

 

[xsn10s]

If this is Gordon's reloading Tool then it's in the class of quickload.

 

[akmtnhnt]

I'm not familiar with that software. So do you have the case with that 52 gr load and bullet? How did you measure the bullet dimensions for the data imput? Did you use a micrometer, an optical compartor, or some other tool? Links for the softer/ equipment or pics of your findings would help. Still sounds like just a guess. It's not using actual pressure monitoring equipment.

Micrometer for the bullet dimensions. I've not put 52gr of LVR in a brass 308 case, as it's way too high to care about.
GRT does actually interface with PT2(https://www.shootingsoftware.com/pressure.htm). And comparing what it's telling me pressure is for my measured muzzle velocity and corrected powder values to the guys running the same thing with the PT2 on discord is why I'm rather confident it's well within the 15kpsi margin of error we're talking about here.
If it was anything but LVR and RL17(the two powders I use the most and have a lot of data on), I'd agreed it's a swag, as I've seen firsthand the default powder values not be all that close, but I do have corrected values for those powders that correlates to actual pressure traces shared on discord.
Real trace in my rifle, no. Closer than 15kpsi, yes.

 

[xsn10s]

Micrometer for the bullet dimensions. I've not put 52gr of LVR in a brass 308 case, as it's way too high to care about.
GRT does actually interface with PT2(https://www.shootingsoftware.com/pressure.htm). And comparing what it's telling me pressure is for my measured muzzle velocity and corrected powder values to the guys running the same thing with the PT2 on discord is why I'm rather confident it's well within the 15kpsi margin of error we're talking about here.
If it was anything but LVR and RL17(the two powders I use the most and have a lot of data on), I'd agreed it's a swag, as I've seen firsthand the default powder values not be all that close, but I do have corrected values for those powders that correlates to actual pressure traces shared on discord.
Real trace in my rifle, no. Closer than 15kpsi, yes.

So are you using the strain gauge with Gordon's Reloading Tool?

 

[Teri Anne]

This thread would be dedicated to ways to improve the performance of the 308 Win or the 7.62x51 mm cartridge without wildcatting the case. Experienced and innovative reloaders should find this interesting and are encouraged to participate. The 308Win is so versatile, inherently accurate and commonly used, and yet its performance in terms of MV, trajectory and speed is a bit mediocre. I am sure it can out perform the 3006. To start with I offer up my favorite hunting load I have used for the past 6/7 years in the 308Win. The 150 gr BD or BD2 with 49 gr of Leverevolution going 2920 fps from a 1:10, 20"Douglas barrel in a short action rifle. The same load from a 24" Bartlein 1:9 twist barrel goes 3050 fps. This load would be a pretty decent long range Elk load to 900 yds or so.

I find several things in this post interesting and not really in a good way. First of all while it is possible to doctor up a 308, it is never in anybody's wildest dreams going to outperform a 30-06. For one, even to attempt it would require increased pressures that would at the least be dangerous. Unless you have pressure testing equipment to even try increasing the so called performance of the 308 to 30-06 standards without exceeding maximum pressures. If you stop and think about it, they worry about pressure differences between a 308 Rem and 7.62 NATO and it would take several thousand pounds more pressure to boost the performance of the 308 to anywhere close to 30-06 performance. I have shot both the 30-06 and 308 in 1000 yard competition and found that the 308 even when loaded to max velocity and pressures is not even close to even making it reliably out too 1000 yards without keyhole hits on the target while the 30-06 makes short work of 1000 yards. You are espousing Elk out to 900 yards. That to me, and I am sure a lot of others would be unethical. There is not all that much difference between 900 and 1000 to make much difference but the 308 would not have enough energy at 900 much less accuracy to really be effective at downing an Elk. All in all, play with your rifle, hope you don't blow it and yourself up. and others around you in the quest of your dream. Be safe and keep in mind that there are many tombstones around the world that may have the epitaph, "If only his firearm hadn't blown up he may be here with us today. Let the flames begin.

 

[nralifer]

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What is "better"?
Flatter trajectory? Use a lighter bullet
More energy? Use a heavier bullet
More speed? Use a longer barrel or some of the newer powders.
More energy at subsonic speeds? Use the heaviest bullet your twist will allow.
You can try a bullet with less engraving pressure/shorter bearing length to increase your speeds too--certain monos and cup/core bullets would fall under this area

But every cartridge has its limitations


Ive gotten a178 ahh up to 2950fps from a 21" 30-06.
I havent had time yet to fool with that bullet in the 308, but I will try it at some point.

Just remember that you'll need enough energy for the animal you're hunting AND you'll need enough speed for reliable expansion for the bullet your using.

What is "better"?
Flatter trajectory? Use a lighter bullet
More energy? Use a heavier bullet
More speed? Use a longer barrel or some of the newer powders.
More energy at subsonic speeds? Use the heaviest bullet your twist will allow.
You can try a bullet with less engraving pressure/shorter bearing length to increase your speeds too--certain monos and cup/core bullets would fall under this area

But every cartridge has its limitations


Ive gotten a178 ahh up to 2950fps from a 21" 30-06.
I havent had time yet to fool with that bullet in the 308, but I will try it at some point.

Just remember that you'll need enough energy for the animal you're hunting AND you'll need enough speed for reliable expansion for the bullet your using.

I use leverevolution for a 308 base cartridge and have it really dialed for what it'll give me. But 52gr LVR in a 308 with the 150SBD-2. Ya, right around 3200fps. But also 75kpsi. So, no, it doesn't do that safely or remotely an apple/apples comparison with anything else.

I'm actually responding to akmtnhnt. Somehow the other posts got tagged on. So here goes. The data in the photo is from a test I was doing comparing the 150 BD2 to another bullet. I used Lapua LRP brass, a BR-2 primer and a 24" barrel rather than a 20" barrel. The notes at the bottom of the data indicate no pressure signs were noted with either bullet. Additionally the primers did not loosen up or flatten. There was noticeable recoil increase though. Akmtnhnt is justifiably concerned about overpressure at this juncture, but no overt sigs of overpressure were showing up. I need to see if the same speed can be achieved with 51 gr LVR from my 26" barrel. Of note, LVR is slower burning than CFE223, a faster burning powder than LVR, for which there is pressure data in the 2021 Hodgdon Annual Manual and 150 gr bullets showing 57,000PSI FOR 51.5 gr of CFE223, so a 1/2 gr more of a slower powder did not seem unsafe since the barrel length in both instances was 24".

 

[Ronald W Schaefer]

This thread would be dedicated to ways to improve the performance of the 308 Win or the 7.62x51 mm cartridge without wildcatting the case. Experienced and innovative reloaders should find this interesting and are encouraged to participate. The 308Win is so versatile, inherently accurate and commonly used, and yet its performance in terms of MV, trajectory and speed is a bit mediocre. I am sure it can out perform the 3006. To start with I offer up my favorite hunting load I have used for the past 6/7 years in the 308Win. The 150 gr BD or BD2 with 49 gr of Leverevolution going 2920 fps from a 1:10, 20"Douglas barrel in a short action rifle. The same load from a 24" Bartlein 1:9 twist barrel goes 3050 fps. This load would be a pretty decent long range Elk load to 900 yds or so.

The thread that just won't die. If you're getting 2900 with 150 weight bullet or 2800 with a 165 you are about done in the .308, btw those are good numbers. The only thing you might could do is find a bullet with secant ogive or some other BC enhancing feature like Scirocco or Sierra Tipped Game King. BTW, those numbers are good for Elk to about 400-500 yds with good shot placement. If you think you need more, you need another cartridge.

 

[JAYgs8163]

The thread that just won't die. If you're getting 2900 with 150 weight bullet or 2800 with a 165 you are about done in the .308, btw those are good numbers. The only thing you might could do is find a bullet with secant ogive or some other BC enhancing feature like Scirocco or Sierra Tipped Game King. BTW, those numbers are good for Elk to about 400-500 yds with good shot placement. If you think you need more, you need another cartridge.

Or the a bullet we're current using. Badlands BD2 150.

Length: 1.385″ BC (G1): .515 BC (G7): .264 Min rate of Twist: 1-11″

Heres my load performance using 49 gr of LeverEvo from a 18" barrel. Accuracy under 1/2 moa. I had great accuracy between 47-49 and will stay in that area. No pressure signs at all on SRP Alpha brass. At 47.5 was just under 3k.

 

[nralifer]

A lot of muzzle velocity chrono data with different volume and initial pressure charges corrected for combustion coefficient and isentropic exponent, working backwards. It might not be right at 75kpsi but it's in the ballpark. Wildly over the 60k that round is rated at.
I actually have pretty good data at those pressures with that powder and a touch higher to know what to adjust the variables to for the burn rates at those pressures to match real world results.

When I saw 52gr of LVR in a 308 I went.. wait a minute, checked my data and ya.

I certainly can understand your concern given that it sounds like you have pressure measuring equipment. My question to you is, do you have any data on CFE223 in the 308Win using the 150 gr BD2, specifically 51.5 gr given the fact that Hodgon says the pressure with a 150 gr lead core bullet should be 57Kpsi?

 

[xsn10s]

The SS 150 gr doesn't have a better BC than the BD2 150 gr. Plus I'd bet it has more bearing surface. I don't see Sierra even listing a 150 gr TGK. Nosler lists a 165-168 gr load pushing 2900 fps using Big Game and has their 150-155 gr bullets right near 3000 fps. I could see LeverEvo getting to 3100 fps with a 150 gr bullet. Especially one with less bearing surface.

 

[JAYgs8163]

Look at the Barnes data for 150's. There right at 3k on their 150 with more bearing surface and a significantly lower BC. Using similar powders.

 

[USAFRet]

So, the 150BD2 lists a minimum twist of 1:11. Pardon me for my ignorance, but does that mean a faster twist is okay or is the minimum going by the number? All of mine have 1:10. Very interested in this bullet when I get back to buying components again.

 

[nralifer]

The thread that just won't die. If you're getting 2900 with 150 weight bullet or 2800 with a 165 you are about done in the .308, btw those are good numbers. The only thing you might could do is find a bullet with secant ogive or some other BC enhancing feature like Scirocco or Sierra Tipped Game King. BTW, those numbers are good for Elk to about 400-500 yds with good shot placement. If you think you need more, you need another cartridge.

You are thinking along the right direction, but the current 150 gr BD2 already has a higher BC than the Scirocco, and the same G1BC as Sierra tipped 155 gr Match King. I can't find a 150 or 155 gr tipped Game King, only a 168 gr tipped Game King.