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150 vs 180 gr 308
- Thread starter Oleg Volk
- Start date
Art Eatman
Staff in Memoriam
Aw, just sit around and wait for a bit; plenty more ammo coming. I guess the worriers are stocking up--again? Still?
I doubt you'd lose any accuracy, unless your barrel twist rate is real slow. Out beyond 300 yards, since the trajectory would be different you might shoot a bit lower with the 180-grain...
Art
I doubt you'd lose any accuracy, unless your barrel twist rate is real slow. Out beyond 300 yards, since the trajectory would be different you might shoot a bit lower with the 180-grain...
Art
Assuming a 150gr@2700 and a 180gr@2500, here is the comparison if each is zeroed at 200y. The first row of data is the point-of-impact relative to point-of-aim, in inches. The second row is the MOA of elevation required to "zero" at that range, if you had an elevation target knob.
If you have a gun whose sight is regulated for 200 yards with 150gr@2700fps, and you shoot the 280gr at 2500fps:
Subtract the columns "down" to get difference in point of impact for 180 vs. 150 at various ranges. E.g.: at 300 yards, the 180gr will be 3.45" below the 150gr; at the zero range, 200y, the 180gr will be 1.57" below the 150gr.
This data is using published BC values from Sierra and the G1 drag model. My spot-checks have matched the published trajectories in the Hornady book by no more than 0.2 MOA at 1000 yards.
Other data: for a 9lb rifle, the 150gr@2700 will have a free recoil energy of 5.81 ftlbs, and the 180gr@2500 will have a FRE of 7.17 ftlbs.
Enjoy.
-z
ps. If you have actual BC and velocity values, I can calculate the "real" trajectories of the two loads.
Code:
BC MV 0y 100y 200y 300y 400y 500y 600y
0.408 2700 -1.43 2.09 -0.01 -8.91 -25.76 -52.60 -90.43 5.830 moa | Sierra 150gr GameKing FMJBT
0.00 -1.99 0.00 2.84 6.15 10.05 14.42 MOA
Far zero at 200.1 yards, maximum 2.15 at 115.9 yards
0.495 2500 -1.43 2.47 -0.01 -10.02 -28.55 -57.49 -97.45 6.573 moa | Sierra 180gr MatchKing HPBT
0.00 -2.36 0.00 3.19 6.82 10.98 15.54 MOA
Far zero at 200.1 yards, maximum 2.53 at 113.7 yardsIf you have a gun whose sight is regulated for 200 yards with 150gr@2700fps, and you shoot the 280gr at 2500fps:
Code:
0y 100y 200y 300y 400y 500y 600y
0.408 2700 -1.43 2.09 -0.01 -8.91 -25.76 -52.60 -90.43 5.830 moa | Sierra 150gr GameKing FMJBT
0.495 2500 -1.43 1.69 -1.57 -12.36 -31.67 -61.39 -102.12 5.830 moa | Sierra 180gr MatchKing HPBSubtract the columns "down" to get difference in point of impact for 180 vs. 150 at various ranges. E.g.: at 300 yards, the 180gr will be 3.45" below the 150gr; at the zero range, 200y, the 180gr will be 1.57" below the 150gr.
This data is using published BC values from Sierra and the G1 drag model. My spot-checks have matched the published trajectories in the Hornady book by no more than 0.2 MOA at 1000 yards.
Other data: for a 9lb rifle, the 150gr@2700 will have a free recoil energy of 5.81 ftlbs, and the 180gr@2500 will have a FRE of 7.17 ftlbs.
Enjoy.
-z
ps. If you have actual BC and velocity values, I can calculate the "real" trajectories of the two loads.
Amen, smithz! I worked in sales at a gunshop for six years and I can't tell you the how many "Should I buy a .270 instead of a 30-06 because it is so much flatter shooting?" questions I've been asked. Once I was proposed this question (roughly): "I have a .308 that I want to hunt fox with. I want the fastest, flatest, least damaging bullet/load combination?" "What ranges are you talking about?" "400 plus yards." Thinking I had an open minded client I proposed a heavy, slow expanding bullet at a moderate velocity. Not only would the B.C. be better than these screamer 110 and 125 gr. loads but hide damage would be less due to less expansion. I even went on to pull out a Sierra reloading manual with similar tables as you have provided. He looked at me like I was crazy and walked out. I guess the customer is always right and I should have handed him a box of 110 HP and some fast burning powder. P.S. Oleg Volk: This is no way and attack on your question as it really doesn't even directly relate. It it is a kudos to smithz for eloquently illustrasting the relatively small differences in trajectory due to bullet weight/B.C..
With my eye sight, known lousy technique and probable poor inherent accuracy of the rifle I doubt that I'll ever take a shot past 150m anyway...was just curious. Everyone seems to want 147-150 gr military ball and I prefer soft points. Having seen how completely Barnaul 7.62x39 blew up during testing, I can see an argument for a heavier projectile which would expand some and penetrate more. Will test some of each and see what happens. Wonder if the recoil will be appreciably different.
Good comments, Leafy. Note, however, that if you do not re-sight-in with the heavier bullets, you will be 6" low at 400 yards. Whether or not that matters is up to you.
I know that 6" is just on the border on what I would be able to notice, shooting my FAL, iron sights, at 400 yards.
If 150gr ball's terminal ballistics aren't good enough - and I would never, ever shoot game with one - get some loads with good hunting bullets. Something that expands, but is either bonded or has a "solid" base, like a Nosler Partition.
As for your varmint example, chew on this. Each zeroed at 200y.
All data lifted from the Hornady book. G1 model, etc.
This is now totally off topic, but "flat-shooting" is less important that "consistent shooting", for a real long-range rig with a scope with elevation knobs, assuming you don't run out of adjustment.
-z
I know that 6" is just on the border on what I would be able to notice, shooting my FAL, iron sights, at 400 yards.
If 150gr ball's terminal ballistics aren't good enough - and I would never, ever shoot game with one - get some loads with good hunting bullets. Something that expands, but is either bonded or has a "solid" base, like a Nosler Partition.
As for your varmint example, chew on this. Each zeroed at 200y.
Code:
0y 200y 400y 600y 800y
0.247 3700 > -1.46 -0.00 -16.05 -63.16 -167.84 > 3.613 moa | .22-250, 53gr A-MAX
0.330 3300 > -1.45 -0.00 -17.79 -65.18 -159.11 > 4.201 moa | .243WIN, 75gr A-MAX
0.400 3100 > -1.45 -0.01 -18.91 -66.89 -156.81 > 4.579 moa | .243WIN, 87gr A-MAX
0.370 3300 > -1.45 -0.00 -16.89 -60.58 -143.92 > 4.149 moa | .270WIN, 110gr A-MAX
0.486 3000 > -1.45 -0.01 -19.02 -65.45 -148.61 > 4.761 moa | .270WIN, 140gr A-MAX
0.290 3400 > -1.45 -0.00 -17.75 -66.93 -169.17 > 4.060 moa | .30-06, 110gr V-MAX
0.435 3000 > -1.45 -0.01 -19.76 -68.99 -159.47 > 4.809 moa | .30-06, 150gr A-MAX
0.505 2700 > -1.43 -0.01 -23.86 -81.65 -184.92 > 5.714 moa | .30-06, 180gr BTHPThis is now totally off topic, but "flat-shooting" is less important that "consistent shooting", for a real long-range rig with a scope with elevation knobs, assuming you don't run out of adjustment.
-z
Good data, smithz. Hypothetically, the heavier bullets will have similar trajectories even at slower velocities while producing less hide damage due to slower expansion. I know this can be countered with examples of light bullets with controlled expansion (Barnes .224 55 gr.) and heavile fragile bullets (the Hornady 7mm A-Max comes to mind). Thanks for the .270/30-06 data. P.S.: elevation probelem countered by Burris Signature rings or tapered bases, but I'm sure I don't need to tell you that.