Hey guys/gals, i've just started doing the 'long range' shooting thing here over the last year. I've been shooting 168 grain Hornady Amax's from my .308 at ranges pushing 700 yards with fairly good luck. My question is, what's the difference between 168 and 175 grains with wind? Does the 175 grain not get pushed around by the wind as much? i'm not all that good at judging wind, and don't have the tools to measure wind yet. I mostly just try to shoot on calm days. I understand there will be a little difference, my question is how significant of a difference? Thanks ya'll. hvychev77
168 vs 175
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el matador
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In many cases a heavier bullet will drift less, provided your gun can push that bullet fast enough to take advantage of the higher BC. With a .308 you don't really have enough power to accomplish that. 165-180 grain bullets will be very similar with respect to wind drift since the higher BC of the heavy bullet will be offset by the longer flight time. You may find a small difference depending on your specific accuracy load but it won't be very big. In a 300 Win Mag you'll see a major difference between 165s and 200s in wind drift since that cartridge can push the larger bullets harder.
Unofficial Gun Addict (UGA)
Well-Known Member
^^^^^
I agree with the above statement, however, if you can push the heavies fairly quickly, then the amount of energy they retain is pretty amazing. Really depends on your barrel twist... But my 11 twist can stabilize the 215s that I'm throwing and wow do they perform. Using them for elk next year and they retain upwards of 1k ft/lbs at 900 yards. Pretty amazing performance out of a 308.
The bullets are berger hybrid 215s.
I agree with the above statement, however, if you can push the heavies fairly quickly, then the amount of energy they retain is pretty amazing. Really depends on your barrel twist... But my 11 twist can stabilize the 215s that I'm throwing and wow do they perform. Using them for elk next year and they retain upwards of 1k ft/lbs at 900 yards. Pretty amazing performance out of a 308.
The bullets are berger hybrid 215s.
Michael Eichele
Well-Known Member
Higher BC = less wind. Period.
208 amax starting at 2600'sec has less drift at 1K than a 168 SMK starting out at 3500'sec.
A 168 is faster yes but as long as the 175 is proportionally as fast, it will have less drift. If you want the least drift, use a 215 hybrid. If you want a good balance of recoil, energy, trajectory and drift, look at the 185 Juggernaut, 185 hybrid and 190 VLD. Compare those against any 168 or 175.
I often hear those statements about heavies not working well in 308s because the BC doesn't overshadow the loss in velocity. I still haven't figured that one out. I think the 308 needs all the help it can get and the 168s don't do anything to help it. The 175-210+ do a lot to help it.
Just my .02
M
208 amax starting at 2600'sec has less drift at 1K than a 168 SMK starting out at 3500'sec.
A 168 is faster yes but as long as the 175 is proportionally as fast, it will have less drift. If you want the least drift, use a 215 hybrid. If you want a good balance of recoil, energy, trajectory and drift, look at the 185 Juggernaut, 185 hybrid and 190 VLD. Compare those against any 168 or 175.
I often hear those statements about heavies not working well in 308s because the BC doesn't overshadow the loss in velocity. I still haven't figured that one out. I think the 308 needs all the help it can get and the 168s don't do anything to help it. The 175-210+ do a lot to help it.
Just my .02
M
Thanks everyone. I never thought about the travel time of the bullet. My gun does have a 1 in 10 twist so, i might could get by pushing a heavier bullet. The only disadvantage i would have is a 22" barrel as far as velocity is concerned. I guess the only way to truly prove it out as a beneficial test is to buy some and try them. Thanks again. Merry Christmas!!
I shoot both in my 308's. This is the difference in a full value wind at 10 MPH wind at 700 yards......1 inch less drift with the 175 gr. All conditions identical.
168 SMK, 2700FPS, 36.5"-10MPH-700 yards, 17.25 MOA elevation
175 SMK, 2650FPS, 35.5"-10MPH-700 yards, 17.5 MOA elevation
168 SMK, 2700FPS, 36.5"-10MPH-700 yards, 17.25 MOA elevation
175 SMK, 2650FPS, 35.5"-10MPH-700 yards, 17.5 MOA elevation
Michael Eichele
Well-Known Member
Not sure how you're getting a inch. At 700 it should be about 4-5". At a grand it's a foot.
Michael Eichele
Well-Known Member
I am not going to sit here and tell you that time of flight does not affect windage. Because it does affect it. It does not affect it as much as most people think. Time of flight has more to do with trajectory than windage. It is the lag time within the time of flight affects windage. The ballistic coeffiecient is what determines the lag time within the time of flight.
I did have an error in that the drift was for an 8 MPH wind, not 10, but the stated difference between the two loads is still the same as shown in the post. This is calculated both in Shooter, and what I have experienced at least out to 600 yards with my 308 in competition. I double checked my info. I don't think I'm missing anything but would welcome feedback as to where I'm going wrong if I'm off.
Michael Eichele
Well-Known Member
I'm also using shooter. What BC values are you using?
At 600, they are pretty close. Just over 2" at 5000' but 3.5 at 0'.
Sierra lists the 175 at .505 down to 2800 which most guys don't run that fast. We're left with .496 to 1800 and .485 to 0. Average being .4905G1
They list the 168 at .462 to 2600, .447 to 2100, .424 to 1600 and .405 to 0. Most of its flight will be under 2600 for and average of .425G1.
If you use sierras data you'll come up with about 2.5" difference at 600 yards. If you use litz data, you'll still come up with about 2.5" at 600.
You're right, it's not a huge difference at 600 or 700 but it is a fair bit difference further out.
I would think that "what rifle"would make big difference: a 28 inch barrel model 12 FT-r vs a 16 inch ar. i have shot 167 scenars out of my 30-06, they work great. also the 155 berger appears to me as long as a 175 and you drive them faster.
You were correct Michael. I had an error in my Shooter inputs of the BC's. After correction, my 700 yards difference was 4.6" advantage to the 175 SMK over the 168 SMK with an 11" advantage at 1000 yards. Very close to your data. Sorry for the confusion. Art
