Improving the 308 Win performance

[xsn10s]

I don't see the current mk248mod1 from Sig as being too spectacular. If the BC's pan out then a 175 BD2 with MV of 2700 fps isn't going to be far behind a 190 SMK a 2950 fps. And as far as I can tell the current mod 0 from Sig is going 2850 fps with the 190 SMK. I'd be more excited if it was a 215 Berger Hybrid at 2800 fps (30-06 area). Besides military application isn't the same as hunting applications, at least officially.

 

[QuietTexan]

I have both .308 and 30-06, plus AI versions of both.

Interesting, what are your actual gains on the 308 AI? Not many of those floating around, so I'd like to hear real numbers.

Of all the AIs, 308 and 7-08 aren't top of the heap in terms of papers gains. But then you have the 243 AI with a huge jump, 10+% depending on brass thickness off the same 308 parent. I've always noodled a 7mm-08 AI because on paper it's the perfect 7MM to use to save a 6.5CM action, just not sure the juice is worth the squeeze there with the low paper ratings. Alpha is making brass now though, and I have a Bergara with a rusted mess of a bore....... so it might be time.

 

[Hugnot]

Should you want or need something with better performance get a larger capacity cartridge. Should you want or need a .30 caliber military cartridge for full or semi auto weapons get a .308 W or 7.62X51.

The nice .308 Win is what it is.

 

[DoneNOut]

The use of Hammer 137HH with AA2520 or TAC cruising it at 3100-3200fps is certainly increasing the 308 WIN performance! Then there is the terminal ballistics advantage.

 

[longtubeman]

I agree. I'm ready to try it. Might have some results on Wed next week when the temp gets above 0 so I can use my radar.

Yes you can get 2900 fps! I have a Savage 10 in 308, with a 26 in barrel. I shoot a barns 175, lrx at 2900 with 52 gr ( drop tube) of ww760 , and a 210m primer.ran that at 3200 ft, with 80 degrees.

 

[Hugnot]

Decades ago when I lived in Colorado this guy I knew shot lots of big deers with a .308 Win loaded with some kind of ball powder & 130 grain bullets because he did not have a .270 Win. Light .30 bullets, like anything under 150 grains not so good over 300 yards. Palma shooters use .308's with 155's (rules) at 700, 800, 900 & 30 inch barrels are common. They would probably have better scores with 6.5 CM's.

 

[nralifer]

I don't see the current mk248mod1 from Sig as being too spectacular. If the BC's pan out then a 175 BD2 with MV of 2700 fps isn't going to be far behind a 190 SMK a 2950 fps. And as far as I can tell the current mod 0 from Sig is going 2850 fps with the 190 SMK. I'd be more excited if it was a 215 Berger Hybrid at 2800 fps (30-06 area). Besides military application isn't the same as hunting applications, at least officially.

With SRP brass, LVR powder, PT&G 308win bore rider chamber and a 26" or 24" 1:10 twist barrel you can safely propel the 175gr 308BD2 to 2800-2850 fps. No magnum cartridge needed. Primer I use is the CCI450. COAL =2.950-2.960". 30-06 length action is not needed but the round seems to feed a little easier in the longer action.

 

[nralifer]

Yes you can get 2900 fps! I have a Savage 10 in 308, with a 26 in barrel. I shoot a barns 175, lrx at 2900 with 52 gr ( drop tube) of ww760 , and a 210m primer.ran that at 3200 ft, with 80 degrees.

Excellent! Now, if you use a bullet of the same weight and better BC you will get better supersonic range out of that speed. I, of course, recommend the 175 gr BD2 bullet. Your barrel is probably the same as mine. Dave Kiff sold Savage 308Win reamers with extended throats he called bore rider throats. The COAL of a dummy round needed to reach the lands in my barrel with that bullet is 3.05".

 

[Bravo 4]

I don't see the current mk248mod1 from Sig as being too spectacular. If the BC's pan out then a 175 BD2 with MV of 2700 fps isn't going to be far behind a 190 SMK a 2950 fps. And as far as I can tell the current mod 0 from Sig is going 2850 fps with the 190 SMK. I'd be more excited if it was a 215 Berger Hybrid at 2800 fps (30-06 area). Besides military application isn't the same as hunting applications, at least officially.

The MK248 mod 0 is really averaging less than 2900 anyway. The bad thing is rifle to rifle we can go from 2740-3000+fps.
The new ammo we have tested (and SFSC shoots) in the MK22 is a 215 Berger going 2950-3000+ fps (300 Norma). I have been really impressed so far. After zeroing in only a few rounds, I went 3 for 3 the other day on a 1/2 moa tall target just trying to get a quick trueing on a new barrel with a guessed 2950 fps. What we have needed for well over a decade wasn't necessarily a new rifle/cartridge, but a more modern projectile. Now we are getting all 3 in our PSR. I think we also need to go that route with the M118LR in our 7.62x51 M110 SASS. The 175 Matchking is decades old technology and frankly a ballistic turd compared to others.

 

[xsn10s]

The MK248 mod 0 is really averaging less than 2900 anyway. The bad thing is rifle to rifle we can go from 2740-3000+fps.
The new ammo we have tested (and SFSC shoots) in the MK22 is a 215 Berger going 2950-3000+ fps (300 Norma). I have been really impressed so far. After zeroing in only a few rounds, I went 3 for 3 the other day on a 1/2 moa tall target just trying to get a quick trueing on a new barrel with a guessed 2950 fps. What we have needed for well over a decade wasn't necessarily a new rifle/cartridge, but a more modern projectile. Now we are getting all 3 in our PSR. I think we also need to go that route with the M118LR in our 7.62x51 M110 SASS. The 175 Matchking is decades old technology and frankly a ballistic turd compared to others.

Yup I agree. The 215 Hybrid is a far better projectile. The US military has a poor history of picking the best cartridge/ projectile for our uses. And the statement of "What we have needed for well over a decade wasn't necessarily a new rifle/cartridge, but a more modern projectile." fits with this thread. A higher BC bullet with excellent terminal performance is going to stretch any cartridge's range and capability. Which IMO was the point of this thread.

 

[Hugnot]

Max loads for 175's with 49 gr. H414/W 760 in Hodgdon data run 2629 fps, 50,100 CUP/58,043 PSI.

Any idea of pressure to get 2,900 fps (271 fps increase) with 52 gr. H414/W 760 (3 gr. increase)?

The US military picked the M240 machine gun that uses 175 gr. loads at up to 60K psi. Any idea of performance or reliability issues upon increasing pressures beyond 60K psi. Would a 3.0 COAL round work in a M240? Military applications require full auto weapons. The 7.62X51 NATO works real good for military purposes.

The pricy Berger 215, used in a bolt gun, at pressures near 64,000 psi would outperform 175 gr. 7.62X51 rounds fired from a M240.

The US Military has picked the 6.5CM for cartridge/projectile use. Given the choice, I sure would do the same, rather than make the little .308 Win do something it was never intended to do.

My experience with small rifle primers like CCI 450's and ball powder amounts that would be used in .308 loads, showed large velocity spreads, especially a low temperature. 52 grains of 760/H414 is going to need a hotter primer.

 

[nralifer]

Yes you can get 2900 fps! I have a Savage 10 in 308, with a 26 in barrel. I shoot a barns 175, lrx at 2900 with 52 gr ( drop tube) of ww760 , and a 210m primer.ran that at 3200 ft, with 80 degrees.

What you have demonstrated and confirmed is that the 308Win can generate as much bullet energy as many 300Win mag published loads. The 308 Win cartridge is much more efficient than the virtually any other big 30 cal. In your case at 2900 fps the bullet energy is 3267 ft-lbs. Divide that by the powder weight (52gr) it took to do that you get 62.8 ft-lbs of bullet energy per grain of powder used. I looked through the 2015 Hodgdon Annual Manual at all 30 cals that used the same powder (H4895), same barrel length (24"), same barrel twist, same bullet weight (150 gr), took the MV of the highest load for each case, calculated the bullet energy and divided that by the powder charge it took to drive that bullet to the energy level recorded. The 308Win wins, at 61.1ft-lbs/ gr of power with the second most efficient cartridge being the 30-06. The least efficient was the 300 Weatherby and the second least efficient was the 300WM. I can verify that with a 150 gr BD2 from a barrel of the same length and twist as yours I get 3180 fps with 52.5 gr of LVR using Palma Lapua brass and the CCI450 SRP with the just beginnings of primer flattening. Bullet energy was 3367 ft-lbs divided by 52.5 gr of LVR gives 64.1 ft-lbs/ gr of powder. What is the point of all this, the 308Win remains THE most cost efficient big game hunting and sniper cartridge out there when coupled with the best reloading components available, and can safely reach bullet energy levels associated with published 300WM loads.

 

[xsn10s]

With SRP brass, LVR powder, PT&G 308win bore rider chamber and a 26" or 24" 1:10 twist barrel you can safely propel the 175gr 308BD2 to 2800-2850 fps. No magnum cartridge needed. Primer I use is the CCI450. COAL =2.950-2.960". 30-06 length action is not needed but the round seems to feed a little easier in the longer action.

I never looked into using LVR powder in a 308 Win. I did a search and found a thread with LVR and 200 gr Speer. Very interesting, new options! That 175 gr 308BD2 load is very interesting. Nice work.

 

[xsn10s]

Hmmm looks like Remington's SPS Varmint 308 Win comes with a 26" 1-10" barrel. My PSS has a 1-12" twist. I may need to keep an eye out for a trade.