Advanced Marksmanship 175 smk high fps vs 208 slower fps at long dist

[taseal]

I can get a 175 SMK to almost 3,000fps where a 208 amax will be around 2600-2700

at longer distances, which shall prevail?

I'm assuming the heavier bullet?

also the 208 amax will probably be less prone to cross wind even though it's moving slower. but with the 175 smk you can probably get to the target faster, so less time fiddling and being pushed around by the wind...

This is for a .30-06 btw

I was just curious what people would say, and the logical reasoning behind it.

 

[FCS]

Re: 175 smk high fps vs 208 slower fps at long dist

Take both to 1K and see which does better in the wind. Sometimes you just have to see it with your own eyes to believe.

 

[sled_mack]

Re: 175 smk high fps vs 208 slower fps at long dist

Run the numbers in JBM and you'll see which is better for the wind.

The guys shooting them out of .308s are liking the 208 Amax for bucking the wind, but they are not getting 175 SMKs that fast either. Probably not getting the Amax that fast either, to be fair.

 

[taseal]

Re: 175 smk high fps vs 208 slower fps at long dist

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sled</div><div class="ubbcode-body">Run the numbers in JBM and you'll see which is better for the wind.

The guys shooting them out of .308s are liking the 208 Amax for bucking the wind, but they are not getting 175 SMKs that fast either. Probably not getting the Amax that fast either, to be fair. </div></div>

yeah, i referenced my speeds off a .30-06 which is between a .300WM and .308

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: FCS</div><div class="ubbcode-body">Take both to 1K and see which does better in the wind. Sometimes you just have to see it with your own eyes to believe. </div></div>

it's a 4 hour drive

JBM shows 208 amax will win no doubt. curious... I wish I had a 1000 range near by.

 

[VKC]

Re: 175 smk high fps vs 208 slower fps at long dist

In general the heavier a 30 caliber bullet the higher the BC, thus whichever has a high BC will "prevail" at longer distances if pushed to similar pressures.

 

[Texar2]

Re: 175 smk high fps vs 208 slower fps at long dist

I ran both through jbm but would also like a similar comparison between 155 scenars and 208s. The price of the 208 keeps me coming back to it.

 

[LawnMM]

Re: 175 smk high fps vs 208 slower fps at long dist

I have run the numbers on 208s, 175s, 178s, 185s, 190s, 208s from Hornady, Sierra, Berger, and Lapua...

The 155s have strikingly good performance, as good as the 208 for wind, and better in drop, to 1000 yards. However, as flight time increases, the BC of the 208 takes over and if I remember correctly it was around 1100 yards that the 208 takes over.

The 208s have a great price in comparison to the other good performers like the 155 scenar and Berger 185, at about half the price. I ran the numbers with 308 velocities but the BCs will really tell the tale. If you have a '06 or 300wm the 208 will have less drop at higher velocity and now its really running away with the competition.

If you look at the bread and butter 308 projectile, the Sierra 175gr HPBT, launched at 2650 at sea level as a baseline...

Compare that to a 208 Amax under the same conditions, at 2480fps, and the drop is within 5 inches of the 175 out to 900 yards, at which point it is actually better. Its wind fighting ability is better the entire flight, and it stays supersonic longer.

Ballistically the 208 is pretty hard to beat in a .30 cal with anything but a heavier bullet and its performance, even at lower velocities, is still as good as most lighter bullets. The 155 scenar has much better drop but its moving several hundred fps faster. If you launch a 208 at '06 or 300wm velocity, that advantage dwindles.

I don't think you will find much that shoots better than these 208s unless you go to the 6.5 caliber where it has same/better wind fighting ability and much better drop. None of that means anything of course if we don't put the trigger time in to be able to shoot to the rifle and projectile's potential.

Rich

PS - Go with the 208s.

 

[gugubica]

Re: 175 smk high fps vs 208 slower fps at long dist

Try the 178 Amaxs.

 

[CST]

Re: 175 smk high fps vs 208 slower fps at long dist

Im shooting my 155 Scenars at 2940 fps at 80 deg. It takes 8.3 mils at 1000 and just the other day for the first time hit steel at 1230 yds at 12.3 mils.....
Don't think the 208s can match that because u can't launch em fast enough.....308 is never gonna be a magnum cartridge.

 

[LawnMM]

Re: 175 smk high fps vs 208 slower fps at long dist

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CST</div><div class="ubbcode-body">Im shooting my 155 Scenars at 2940 fps at 80 deg. It takes 8.3 mils at 1000 and just the other day for the first time hit steel at 1230 yds at 12.3 mils.....
Don't think the 208s can match that because u can't launch em fast enough.....308 is never gonna be a magnum cartridge. </div></div>

I never said it was a magnum cartridge. I also said, more than once, that the scenar does much better with drop because its moving faster and has a flatter trajectory. Then again he's not asking about the scenar is he? He's asking about whether a slower moving 208 is better than a faster moving 175 matchking. The answer is, the slower moving 208 is ballistically superior to the 175.

 

[gugubica]

Re: 175 smk high fps vs 208 slower fps at long dist

Pretty much everything is ballistically superior to the 175.

 

[TxShooter63]

Re: 175 smk high fps vs 208 slower fps at long dist

The heavier bullet will have a superior BC and as such superior performance. I might recommend "Applied Ballistics for Long Range Shooting" as a book for you to read.

 

[MD2Colo]

Re: 175 smk high fps vs 208 slower fps at long dist

I was going with your estimated MVs. Also guessed on the 155MV, not sure when the rounds will come apart tho.
for f*ck's sake, I did it for 308. sorry...was assuming 11.25 TR. You prolly have a 1:10?? not sure man

I was bored, if you can't tell.

 

[ArcticLight]

Re: 175 smk high fps vs 208 slower fps at long dist

David Tubbs actually wrote an article about this at one time.

He was shooting, I "BELIEVE", a .308 and shot a 200 or 210 from it and found after 900 yards it had an advantage, nothing more until after 900 though.

Check Zediker.com archives, it may still be there...

 

[TorF]

Re: 175 smk high fps vs 208 slower fps at long dist

There is another issue in this comparison. Assuming the ballistic differences between a 155gr and 208gr are almost identical the next question is: If you shoot the rifle from an unstable platform (without rest or bipod), what bullet is "easiest" to shoot and have an impact on your scores on a formal X-ring target at 300m? My experience is that a light and fast bullet always beat a slow and heavy. Next up is the advatage of shortest possible time of flight.