Staying supersonic at 1000yds with .308?

T

thefitter

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May 10, 2010
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#1
How are you accomplishing this? Only in a 30" barrel? What are your loads?

When I use the jbmballistics calculator I see I need 2750fps for the Berger 185s and 2850fps with the Berger 175s. To get these speeds I'm really pushing up the loads in my 24" tube.


Thanks
 
#2
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thefitter</div><div class="ubbcode-body">How are you accomplishing this? Only in a 30" barrel? What are your loads?

When I use the jbmballistics calculator I see I need 2750fps for the Berger 185s and 2850fps with the Berger 175s. To get these speeds I'm really pushing up the loads in my 24" tube.


Thanks </div></div>

That doesn't make alot of sense, my 175's are supersonic way past 1k and Im shooting a ho hum load out of a 24 inch barrel too.
 
#5
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">Take a look at the DA's you are shooting them under. It makes a big difference. I think CBM's shooting several thousand feet ASL, that is why his load is supersonic well past 1k.

</div></div>

Correct bohem, as usual
grin.gif
Between 4-8000 feet normally.
 
#6
Re: Staying supersonic at 1000yds with .308?

heck I get 2650fps out a 20" rifle and 2600fps out of my 18.5" and I am still supersonic at 1000 yards, even at sea level, let alone here at 5000ft. Those number are from factory ammo.

Don't shoot anything heavier out of the rifles, that is what a bigger gun is for.
 
#7
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thefitter</div><div class="ubbcode-body">You are at Mach 1.2 at 1000 yards in a 24" barrel? What is your load?

Thanks </div></div>

The old standard, I thought everybody shot this load: 44.0gr RL-15
Brother shoots the same out of a 21" and his stays above SS as well.
 
#8
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">heck I get 2650fps out a 20" rifle and 2600fps out of my 18.5" and I am still supersonic at 1000 yards, even at sea level, let alone here at 5000ft. Those number are from factory ammo.

Don't shoot anything heavier out of the rifles, that is what a bigger gun is for. </div></div>

Thank you LL, that's exactly what I was thinking.
 
#9
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bohem</div><div class="ubbcode-body">Take a look at the DA's you are shooting them under. It makes a big difference. I think CBM's shooting several thousand feet ASL, that is why his load is supersonic well past 1k.

</div></div>

That's what it is.

When I ran the numbers at 4000ft ASL I only need 2600fps for the 175s. That's 250fps slower and right in the book load range.

I'm shooting at 20ft ASL.

Thanks
 
#10
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">...I get 2650fps out a 20" rifle and 2600fps out of my 18.5" and I am still supersonic at 1000 yards... </div></div>

Bullet?

Thanks
 
#12
Re: Staying supersonic at 1000yds with .308?

With a 24" barrel, I am getting ~2925 fps with a 155.5 grain bullet with magazine length rounds. These easily make it to 1000 yards, and the good BC of the 155.5 means that it is competitive as well, even against other shooters running 30" barrels and single loading. My load is on the warm side, but is simply a combination of Varget, Fed 210M's, and Winchester brass.
 
#13
Re: Staying supersonic at 1000yds with .308?

The new Hornady 178 HPBT is supposed to be supersonic to 1200 yardsat sea level...

Any 175ish grain projectile at 2600fps or better should get you to 1000
 
#14
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">...2650fps out a 20" rifle and 2600fps out of my 18.5" and I am still supersonic at 1000 yards, even at sea level...</div></div>

Bullet?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">175gr </div></div>

What 175gr bullet is still supersonic at sea level at those muzzle velocities?

Thanks
 
#15
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thefitter</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">...2650fps out a 20" rifle and 2600fps out of my 18.5" and I am still supersonic at 1000 yards, even at sea level...</div></div>

Bullet?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Lowlight</div><div class="ubbcode-body">175gr </div></div>

What 175gr bullet is still supersonic at sea level at those muzzle velocities?

Thanks </div></div>

I do it with a 175g SMK from 2500 ASL down to 2000 BSL, my MV is 2600ish.
 
#16
Re: Staying supersonic at 1000yds with .308?

well according to Sierra Infinity at sea level with 2650 MV and SMK175 at 1000 yards velocity would be 1217.9 and the speed of sound is 1126...

-K
 
#17
Re: Staying supersonic at 1000yds with .308?

You should be able to maintain supersonic with any of the 175 gr smk and similar offerings. May have issues at sea level with lighter bullets. But you should be able to make that happen even with a 20 incher. You will have to dial in more elevation but it should work fine.
 
#19
Re: Staying supersonic at 1000yds with .308?

With many 175 grain bullets (SMK, Nosler CC, Berger OTM, and possibly Hornady 178) the bullet is stable thru transonic anyway, so it's not as important that the bullet stays supersonic. Of course performance (wind deflection, drop, etc) will be better if the bullet is supersonic, but it can still be accurate and predictable below Mach 1.

Example; My tactical ammo out of a 20" OBR is only 2570 at the muzzle, and at sea level in winter conditions hits transonic around 800 yards. But it still prints sub MOA at 1000 in good conditions.

Point is, when using a transonic stable bullet, the 'transonic range' of the bullet is less critical.

-Bryan
 
#20
Re: Staying supersonic at 1000yds with .308?

Bryan, thank you for that bit of information. It explains some things that I have seen that did not make sense according to what is commonly accepted. Also, great book!
 
#21
Re: Staying supersonic at 1000yds with .308?

M118LR is supersonic in my rifle at 1k, 2700 fps by my chrono, as is my own load - 45.0gr Varget, Fed 210M, SMK175.

Now if that 30" barrel is a 1/13 PALMA barrel then y ou may consider jumping DOWN to a 155 and shooting it out at 3300.
 
#22
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ArcticLight</div><div class="ubbcode-body">you may consider jumping DOWN to a 155 and shooting it out at 3300.</div></div>

Hmmm... how exactly do you propose to achieve that without wrecking the brass in one (maybe two) shots?
 
#24
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: memilanuk</div><div class="ubbcode-body"> <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ArcticLight</div><div class="ubbcode-body">you may consider jumping DOWN to a 155 and shooting it out at 3300.</div></div>

Hmmm... how exactly do you propose to achieve that without wrecking the brass in one (maybe two) shots? </div></div>

Very carefully?

Ask the palma sh ooters, I'll shoot an email to my buddy...
 
#25
Re: Staying supersonic at 1000yds with .308?

Scott... in case you forget, I shoot Palma & F/TR myself. Some of the people I know run *very* warm loads - but 3150 is pushing it pretty hard for loads in which you expect the cases to actually be reusable (regardless of make or model).

3300... either someone is pulling your leg, their chrono is b0rked, or they 'reverse-engineered' their velocity from their come-ups - and got it wrong. Most of the time, competitive Palma & F/TR 155 loads are more in the 2950-3050fps range.
 
#27
Re: Staying supersonic at 1000yds with .308?

Milanuk you are correct, BPD459 corrected me:

depending on bullet...

new smk 155 (2156 palma) or the berger 155.5 47.0gr varget in a 30" tightbore krieger
both avg 2985 fps

the lapua 155 scenar (my palma guns favorite bullet), 46.5gr varget for avg 2962 fps

sea level, 55 degree F
 
#28
Re: Staying supersonic at 1000yds with .308?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Ring</div><div class="ubbcode-body">the 175's are good to 1100ish </div></div>

Yep, I just crono'd my new 24" Rem 700 shooting 308 Federal Gold Match 175's and im showing breaking sound barrier at 1075 yards

Hope that helps
 
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