NEMO - OMEN .300 Win Mag AR

It's not irrelevant. There are lots of loads that don't work at 1000 yards because you just can't get the velocity you need out of the .308W case for most bullets/rifle combinations. The 185 Berger is probably the best bullet out there for the .308W. It's not exactly something you can get at Cabelas or Four Seasons commercially loaded.

Staying supersonic, or really transonic (mach 1.2) is challenging with a .308 Winchester at 1000 yards. You need to pay real close attention to the details. What works on a hot Summer day, may not work on a frosty Fall morning and you are probably not going to do it with Sierra 168s or maybe even 175s depending on your load and the length of the rifle barrel.

B
 
bpm990d said:
It's not irrelevant. There are lots of loads that don't work at 1000 yards because you just can't get the velocity you need out of the .308W case for most bullets/rifle combinations. The 185 Berger is probably the best bullet out there for the .308W. It's not exactly something you can get at Cabelas or Four Seasons commercially loaded.

Staying supersonic, or really transonic (mach 1.2) is challenging with a .308 Winchester at 1000 yards. You need to pay real close attention to the details. What works on a hot Summer day, may not work on a frosty Fall morning and you are probably not going to do it with Sierra 168s or maybe even 175s depending on your load and the length of the rifle barrel.

B
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Fair enough, it's not trivial, but then again, keeping supersonic velocity with a .308 is not something I'd recommend to someone who shops for ammo at Cabela's. And grabbing a M1A and a box of Federal Match wasn't really where the discussion started, but then, I am too lazy right now to go back and reread.

Then again, though, equating staying transsonic with shooting 1000 yards isn't valid either. I haven't made my own tests yet, but from what I've read some of the new OTM-style bullets can remain dynamically stable after breaching the barrier. In that case, shooting at that distance, and even retaining enough velocity to remove a threat, becomes viable.
 
bpm990d said:
Try some M852 or Federal Match out of an M14 and let me know how that works at 1000 yards. It's well below supersonic at that range.

B
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I agree with DrRansom. That comment was completely irrelevant. I was referring to the ballistic results of a M118LR. (USMC standard sniper cartridge)
 
bpm990d said:
It's not irrelevant. There are lots of loads that don't work at 1000 yards because you just can't get the velocity you need out of the .308W case for most bullets/rifle combinations. The 185 Berger is probably the best bullet out there for the .308W. It's not exactly something you can get at Cabelas or Four Seasons commercially loaded.

Staying supersonic, or really transonic (mach 1.2) is challenging with a .308 Winchester at 1000 yards. You need to pay real close attention to the details. What works on a hot Summer day, may not work on a frosty Fall morning and you are probably not going to do it with Sierra 168s or maybe even 175s depending on your load and the length of the rifle barrel.

B
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I respectfully disagree about your 185gr Berger bullet comment. In my opinion the 175gr Sierra Matchking is ballistically superior to the 185gr Berger for efficiency at longer ranges. What have people been hearing about the Sierra 190s? I don't have much experience with any 190s.
 
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DrRansom said:
Fair enough, it's not trivial, but then again, keeping supersonic velocity with a .308 is not something I'd recommend to someone who shops for ammo at Cabela's. And grabbing a M1A and a box of Federal Match wasn't really where the discussion started, but then, I am too lazy right now to go back and reread.

Then again, though, equating staying transsonic with shooting 1000 yards isn't valid either. I haven't made my own tests yet, but from what I've read some of the new OTM-style bullets can remain dynamically stable after breaching the barrier. In that case, shooting at that distance, and even retaining enough velocity to remove a threat, becomes viable.
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See my post #29 to DeerSlayer. I was responding to his claim.

You can still shoot reasonably accurately with some bullets depending on how the bullets likes being buffeted through that transition. Sierra 168s don't like it at all and they start tumbling and there are lots of others that don't like it as well. Lapua had some doppler radar range data for some of their bullets that they released about five years ago. You can see where the bullets drag increases dramatically below Mach .8 because of the bullet tumbling.

But that wasn't really the discussion, it was about supersonic flight and how far out a .308W can keep them supersonic.

I'm still curious to see some 1500 yard modeling showing supersonic flight. [thinking]

B
 
Deer Slayer said:
I respectfully disagree about your 185gr Berger bullet comment. In my opinion the 175gr Sierra Matchking is ballistically superior to the 185gr Berger for efficiency at longer ranges. What have people been hearing about the Sierra 190s? I don't have much experience with any 190s.
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I now use the 175gr Berger OTMs over the 185gr HPBT; for me, with the 185s, I actually ran into issues with cartridge capacity for powder before I hit pressure signs. I've not compared the Berger/Sierra 175s.
 
bpm990d said:
Sierra 168s don't like it at all and they start tumbling and there are lots of others that don't like it as well.
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IIRC, Litz said it was because of a shortfall in the boattail of that bullet?


I'm still curious to see some 1500 yard modeling showing supersonic flight. [thinking]

B
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We'll both be waiting a long time for that data, I think.
 
Deer Slayer said:
I respectfully disagree about your 185gr Berger bullet comment. In my opinion the 175gr Sierra Matchking is ballistically superior to the 185gr Berger for efficiency at longer ranges. What have people been hearing about the Sierra 190s? I don't have much experience with any 190s.
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Run the numbers. Just google the G7 BC of both. It's not even close for long range shooting. Read Bryan Litz's website about the 185 Juggernaut.
 
bpm990d said:
Run the numbers. Just google the G7 BC of both. It's not even close for long range shooting. Read Bryan Litz's website about the 185 Juggernaut.
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G1 BCs:
185gr Berger HPBT: 0.560
175gr Berger HPBT: 0.515
175gr Sierra Matchking: .505-.485

http://www.bergerbullets.com/Products/Target Bullets.html
http://www.sierrabullets.com/index.cfm?section=bullets&page=bc&stock_num=2275&bullettype=0

The Bergers have a significant advantage. Frustrating that Sierra doesn't get with the damn program and calculate G7 BCs.
 
bpm990d said:
I'm still curious to see some 1500 yard modeling showing supersonic flight. [thinking]

B
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DrRansom said:
IIRC, Litz said it was because of a shortfall in the boattail of that bullet?




We'll both be waiting a long time for that data, I think.
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I am still waiting for the person I know to send me is information, but you guys can read this. I'll admit I may have been off by 75-100 yards.

https://snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=3384872
 
DrRansom said:
IIRC, Litz said it was because of a shortfall in the boattail of that bullet?
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The old Sierra 180 (1980s) had a boat tail like the Sierra 190 and it was popular for long range Service Rifle shooting at 1000 yards because it would stay supersonic to 1000 yards fairly easily with reasonable loads. In the early 90s Sierra changed the design of the 180s. It no longer worked well at 1000 yards for HP competition and people ran around looking for new old stock so they could shoot long range with their M1s and M14s. Around the mid 90s Sierra came out with the 175 for a military requirement, but it still was not all that great and the BC of the old 173gr. M1 bullet that was loaded into M118 still had a better BC. The 175 Sierra did have much better accuracy.

B

oldstyle180grsierra.jpg
 
Don't bother, I just did it for you.

Army Ammunition Data Sheet. They say 2640 fps out of their test equipment.

m118lrammunitiondatashe.jpg


Sierra 175 G7BC is .243

175sierra2640.jpg


You need to figure out what the speed of sound is at 59° in fps.

B
 
I don't think the G1 ballistics are even worth looking at. It's like comparing a Mack truck to a Ferrari. I think Litz has calculated G7 numbers for most of the common bullets in his book.

None of that really matters when your talking about a .300 Win Mag out of a 22" gas gun though. I'm trying to think of something dumber but I'm having a real hard time. There's an ass for every seat I guess.
 
You want me to just give all this information away for free? [rofl]

It varies according to the atmospherics, but temperature is the most significant variable. That guess would be correct for 91° but it's going to be different for a standard atmosphere temp of 59°.

B
 
bpm990d said:
You want me to just give all this information away for free? [rofl]

It varies according to the atmospherics, but temperature is the most significant variable. That guess would be correct for 91° but it's going to be different for a standard atmosphere temp of 59°.

B
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I'm hanging out at the club on my iPhone. Jeff says hi by the way.
 
Here is a comparison with the Berger 185 Hybrid and a .291 G7 BC launched at 2200 fps. A whopping 440 fps slower at the muzzle. Look at the 1500 yard velocity as compared to the 175 Sierra launched at 2640 fps. They are the same and the 185 did it with less wind drift too. Realistically you can probably get 100 fps slower velocity from the 185 in comparison to the the Sierra 175 because of weight and bearing surface.

B

berger185hybrid2200fps.gif
 
The comparison between the two. Neither one are close to being supersonic at extended ranges at realistic launch velocities.

B


berger185vsierra175comp.gif
 
Gman021 said:
What he called the ".308 load from Heaven" even at standard atmospheric conditions

View attachment 42822
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Try running that with a G7 BC and a more reasonable muzzle velocity for that bullet out of a .308 Win. (Hint, Berger's book lists a bunch of different loads and 2297 fps is the fastest of them all.)
 
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jasons said:
Try running that with a G7 BC and a more reasonable muzzle velocity for that bullet out of a .308 Win. (Hint, Berger's book lists a bunch of different loads and 2297 fps is the fastest of them all.)
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If your running a 30+ inch barrel, 3000 feet above see level, and with the ever changing powders out there, doesn't this seem a bit more possible?
 
Gman021 said:
If your running a 30+ inch barrel, 3000 feet above see level, and with the ever changing powders out there, doesn't this seem a bit more possible?
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Even in that thread you linked to, they were having a tough time getting a 208gr AMAX to 2500. Getting a 230gr to 2600fps? That's a bit out there...?
 
DrRansom said:
Even in that thread you linked to, they were having a tough time getting a 208gr AMAX to 2500. Getting a 230gr to 2600fps? That's a bit out there...?
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That's what I thought when I saw it too but that's what he has. I can ask another person for load data.

- - - Updated - - -


Also, I believe he was running a 32inch barrel.
 
Gman021 said:
If your running a 30+ inch barrel, 3000 feet above see level, and with the ever changing powders out there, doesn't this seem a bit more possible?
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Doubtful. Was that a real-world MV or just what some guy put into the calculator? If it's real I'd like to see what powder he was using. Even in a 30" barrel that's going to be tough to do with a .308 win case. With one of the magnums 2600 or even 2700 is do-able, but those hold like 50% more powder.
 
jasons said:
Doubtful. Was that a real-world MV or just what some guy put into the calculator? If it's real I'd like to see what powder he was using. Even in a 30" barrel that's going to be tough to do with a .308 win case. With one of the magnums 2600 or even 2700 is do-able, but those hold like 50% more powder.
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That is my experience as well. Even with those Berger 185s, I start running out of .308 case capacity before I hit too much pressure sign.
 

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