155g to 1200yards

[Short-bus]

Re: 155g to 1200yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">Just because a thing is do-able doesn't make it wise.

Any combination of ammo and rifle that will spit a 155gr/.308 bullet accurately to 1200yd is going to be a major throat burner. Period.

So, once you've found the absolute limits of ballistic performance, what does it buy you?

Greg </div></div>

So you'll have to replace the barrel, or set it back at 7000 rounds instead of 10K, big whoop (IMO). I only have 2000 through my barrel and i'm already thinking of changing up just to try something else. I'm even considering (GASP!) going to .260.

Branden

 

[MontanaMarine]

Re: 155g to 1200yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Greg Langelius *</div><div class="ubbcode-body">....Any combination of ammo and rifle that will spit a 155gr/.308 bullet accurately to 1200yd is going to be a major throat burner. Period....</div></div>


I wouldn't go as far as saying "Period". Atmo can be a big variable.

Around here, a Scenar started at 2900 fps makes 1200 yards with about 1350 fps retained, calc'd with a BC of .470. Mine take about 38 moa correction at that range.

Even at a modest 2700 fps MV, it will retain over 1200 fps at 1200 yards in local atmo (around 4500' el).

 

[9H_Cracka]

Re: 155g to 1200yards

Folks, here is a good article with pics of the shock wave.

Being supersonic is not the goal; staying above TRANSONIC is, at a given distance.

Based on these pics, you want to be at about Mach 1.1 at your given distance, not just supersonic.

That said, stay tuned for at least one purposely transonic stable bullet to hit the market in 30 cal soon. With all the 16" and 18" 308 semi activity these days, plus the people going back to basics and shooting a factory 308 rifle, I predict this will be the next advance in tactical shooting.

http://riflemansjournal.blogspot.com/2011/01/cartridges-1000-yard-308-load.html

 

[Zak Smith]

Re: 155g to 1200yards

I've made hits with my .308 on a 3' plate at 1350 yards (4000' altitude), but about half the bullets seemed to fall out of the air. With my .260 on the same target I could keep them within about a foot if the wind didn't change.

 

[Fred_C_Dobbs]

Re: 155g to 1200yards

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: _9H</div><div class="ubbcode-body">Folks, here is a good article with pics of the shock wave.

Being supersonic is not the goal; staying above TRANSONIC is, at a given distance.

Based on these pics, you want to be at about Mach 1.1 at your given distance, not just supersonic.

That said, stay tuned for at least one purposely transonic stable bullet to hit the market in 30 cal soon. With all the 16" and 18" 308 semi activity these days, plus the people going back to basics and shooting a factory 308 rifle, I predict this will be the next advance in tactical shooting.

http://riflemansjournal.blogspot.com/2011/01/cartridges-1000-yard-308-load.html </div></div>
DUDE! Awesome shock wave pics, especially the .98 Mach.

Some of the ballistics calculators refer to the transonic fudge factor as "break velocity," usually pegged at around 1300 fps.

Technically, any time the air flowing over the bullet is neither entirely supersonic nor subsonic, the bullet is transonic. So subsonic and supersonic <span style="text-decoration: underline">never</span> touch -- they always are separated by the transonic region -- provided the projectile's passing causes <span style="text-decoration: underline">any</span> disturbance to the air.

If the reports coming back from Afghanistan are to be believed, the 250-gr .338 Lapua Lockbase apparently can make the transonic transition with minimal upset. A .30 to do the same would be Christmas come early.

 

[cmh2007]

Re: 155g to 1200yards

for powder i have something you may want to consider. its alliant 2000mr. i am seeing 3000 with 155 scenars out of lake city brass. and with that particular load i am seeing a standard deviation of 8fps...and an extreme spread of 24fps. the best part is i am seeing no pressure signs like i do with varget, and it meters like water.

 

[notquiteright]

Re: 155g to 1200yards

Just out of curiosity just how much of that powder can you get into a LC case?

 

[175G]

Re: 155g to 1200yards

Tracking this thread and since I tend to be arrogant and defiant when someone says it can’t be done I recently played with the 155gr factory lapua out of the little 20" 1/12 AE but this time to 1300. Since I had no dope (and I suck) it took me six rounds to get on target. They were flying pretty well at 2960 and there was nearly no wind and no discernible wind downrange. After that it hit the 18" consistently but kinda all over: left edge, bottom, right edge etc. and I’m pretty sure I was driving the AE right. So my conclusion is the 155gr factory Lapuas will hit it but at this point requiring that much elevation you are playing artillery if there was wind Im pretty sure I would have be fubar.

Good luck to you I cannot wait to get back home to Australia and shoot there.

 

[308RUG]

Re: 155g to 1200yards

[img:center]Image Editing Made Easy[/img]

Well here it is the plot sheet from the the 155g test.Unfortunately I didn't get time to test it from 1200,only 1100yrds will try it from 12 next weekend.
Although the wind played havoc with the light projectiles and sprayed them a bit well a lot,the elevation held reasonably well. Next time will try to get out earlier to beat the wind to the range. The winds were strong and gusty averaging14 to 15 mph.We wound on 11moa to start then just aimed off according to the wind strength changes. The main point of the exercise was to see if it could be done constantly with reasonable accuracy and taking away the side ways spread it seemed to go well. the load ended up at 47.2g of varget not sure of the exact speed but it seemed to get there in the end and although slightly higher than the recommended dosage of powder it didn't have any major pressure signs. The target I was using, was a standard 1000yrd ICFRA target. Interested to see how the load goes at 1200yrds, minus the wind conditions hopefully.

 

[dar1246]

Re: 155g to 1200yards

The big thing with the 308 is the bullets don't have the BCs. The wind will make or brake you. Even a 2 to 3 mph change in wind will push you 2 to 3 moas. You can walk it in or get lucky and hit. If the conditions are in your favor. Shoot. There is better rounds for that range. Some shooters shoot 10 rounds and walk it in but even after that. The wind is going to kill the percentage of hits.
I would think a 1000 yards would be close to max for the 308.

 

[308RUG]

Re: 155g to 1200yards

Ya I hear ya lol. Nope after the results from this little experiment, I wouldn't use them in a match unless the conditions were ideal as the do become a bit hard to control at the longer ranges on windy days. I think when this barrel wears out and comes up for replacing I will replace it with a barrel that shoots heavier projectiles comfortably as well as the lighter ones, perhaps a 1:10 or 1:11. For now I will just keep the 1:13 for the F-Class and the match rifle for the Match Rifle class and hope nothing goes wrong in a match for either class where I need to change rifles.