Nomosendero
Well-Known Member
I would have never thought this!!
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Long range bullet for 308win
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MontanaMarine
Well-Known Member
I think their are a couple things working here.
First, the .648 BC of the bullet is quite good, so it really retains velocity.
Second, the relatively heavy mass of 208 gr (as compared to say 168-175 gr) retains rotational velocity very well too.
The 1/12 twist is not my pick, but in pushing the limits of the factory issue barrel, I discovered it can do things I would have previously considered impossible.
The 308 with 1/12 twist has a history of letting 168s go sideways at 1000 yards, so common logic would dictate a 200+ gr bullet is out of the question. But when you look at the low BC, and low mass of a 168, it's not so hard to deduce that it loses both forward velocity and rotational velocity significantly faster than the 208.
First, the .648 BC of the bullet is quite good, so it really retains velocity.
Second, the relatively heavy mass of 208 gr (as compared to say 168-175 gr) retains rotational velocity very well too.
The 1/12 twist is not my pick, but in pushing the limits of the factory issue barrel, I discovered it can do things I would have previously considered impossible.
The 308 with 1/12 twist has a history of letting 168s go sideways at 1000 yards, so common logic would dictate a 200+ gr bullet is out of the question. But when you look at the low BC, and low mass of a 168, it's not so hard to deduce that it loses both forward velocity and rotational velocity significantly faster than the 208.
littletoes
Well-Known Member
I think we need to find the rest of the thread to show the rest of the experiment, out to 1800 yards.
That says it all....
That says it all....
MontanaMarine
Well-Known Member
After the relative success at 1120 yards, I wanted to go to an extended range in the transonic region, to see what would happen.
Results are intersting, but inconclusive as to stability. I THINK the bullets were stable, based on one recovered jacket, and relative size of the "group", or more accurately, "beaten zone".
Today I shot the 2560 fps load at a range of about 1850 yards. That distance is beyond the ability of my laser. I went to a lased 1000 yards, then got in the truck, zeroed the trip odometer, and drove .5 miles further out. The odometer isn't too precise, but I figured I had to be somewhere between 1800-1900 yards.
I had mounted the MK4 16X, to give the little 308 some longer legs, in regards to internal travel. I had 83 moa "up" available.
From my drop chart, it looked like I would need about 87.5 moa at 1800 yards.
I dialed up 80 moa on the erector, and applied an additional 2 mils via reticle holdoff. About 87.5 moa total. 3-5 mph wind from 3 o'clock, I dialed 5 moa windage into it.
Touched off the first round, and waited the approx 3.5 seconds for it to get there. Didn't see or hear anything. Snow on the ground made seeing misses nearly impossible. I fired four more rounds with the same data, and figured I'd find craters somewhere near the target.
I drove back to the target. Found my 5-shot group in the dirt about 15 paces in front of the target. My wind call was good. Had I opted a 3 mil elevation holdoff, instead of 2, I would have likely connected with a few.
View of target, note hits short of target.
I only found remnants of one bullet. It appears to have hit point first.
The overall "group" on the ground, viewed from the perspective of the trajectory, appears about 12" wide, with one flyer to the right about 24" out. Vertical spread looks like about 24".
Picture of the individual craters are here:
montanamarine/Targets/1850 yards - Page 1 - Photobucket - Video and Image Hosting
To me they look pretty much like they were coming in point first.
When the snow melts and the ground is dry enough to get a dust signature, I'll try this again. Bullet splatters on the steel should be very telling in regards to stability.
Results are intersting, but inconclusive as to stability. I THINK the bullets were stable, based on one recovered jacket, and relative size of the "group", or more accurately, "beaten zone".
Today I shot the 2560 fps load at a range of about 1850 yards. That distance is beyond the ability of my laser. I went to a lased 1000 yards, then got in the truck, zeroed the trip odometer, and drove .5 miles further out. The odometer isn't too precise, but I figured I had to be somewhere between 1800-1900 yards.
I had mounted the MK4 16X, to give the little 308 some longer legs, in regards to internal travel. I had 83 moa "up" available.
From my drop chart, it looked like I would need about 87.5 moa at 1800 yards.
Code:
Gunsite altitude : 4500 ft.
Bullet weight : 208 grains or 13.48 Grams
Muzzle velocity : 2560 fps
Crosswind speed : 10 Mph
Ballistic Coefficient: .648
Range Velo Time of Energy Path Deflection Total Sight correction Target
city flight to at crosswind drop for setting new lead
LOS of 10.0 Mph zero range 33 fps
-------------------------------------------------------------------------------------
·Yards fps s ft.lbs. in. in. MOA in. Clicks MOA yds ·
-------------------------------------------------------------------------------------
| 0 2560 0.0000 3027 -1.9 0.0 ----- 0.0 ------ ----- 0.00
X 100 2445 0.1190 2762 0.0 0.3 0.30 2.7 0.0 0.00 1.30
| 200 2334 0.2442 2515 -3.9 1.7 0.83 11.2 +5.5 +1.88 2.67
| 300 2225 0.3765 2286 -14.3 4.4 1.40 26.1 +13.3 +4.57 4.12
| 400 2119 0.5151 2074 -31.7 8.2 1.95 48.1 +22.1 +7.60 5.63
| 500 2016 0.6597 1877 -56.7 13.0 2.48 77.7 +31.6 +10.86 7.21
| 600 1915 0.8101 1694 -89.7 18.8 3.00 115.3 +41.6 +14.30 8.86
| 700 1818 0.9713 1527 -132.9 26.6 3.63 163.0 +52.8 +18.15 10.62
| 800 1725 1.1428 1375 -187.3 36.1 4.31 222.0 +65.1 +22.38 12.50
| 900 1636 1.3233 1237 -253.6 47.3 5.02 292.8 +78.3 +26.93 14.47
| 1000 1551 1.5117 1110 -332.2 59.8 5.71 376.0 +92.3 +31.75 16.53
| 1100 1469 1.7080 996 -424.0 73.7 6.40 472.3 +107.1 +36.83 18.68
| 1200 1392 1.9177 895 -533.4 90.0 7.16 586.3 +123.5 +42.47 20.97
| 1300 1322 2.1400 807 -662.0 108.5 7.97 719.4 +141.5 +48.64 23.40
| 1400 1257 2.3722 729 -809.7 128.8 8.78 871.7 +160.7 +55.24 25.94
| 1500 1198 2.6168 663 -980.5 151.2 9.62 1047.1 +181.6 +62.43 28.62
| 1600 1146 2.8728 607 -1176.2 175.6 10.48 1247.3 +204.2 +70.21 31.42
| 1700 1102 3.1400 561 -1399.1 202.0 11.35 1474.8 +228.6 +78.59 34.34
| 1800 1063 3.4173 522 -1650.8 230.2 12.21 1731.1 +254.7 +87.58 37.37
| 1900 1030 3.7039 490 -1932.7 260.0 13.07 2017.6 +282.5 +97.13 40.51
| 2000 1001 3.9995 463 -2246.5 291.4 13.91 2335.9 +311.9 +107.24 43.74Touched off the first round, and waited the approx 3.5 seconds for it to get there. Didn't see or hear anything. Snow on the ground made seeing misses nearly impossible. I fired four more rounds with the same data, and figured I'd find craters somewhere near the target.
I drove back to the target. Found my 5-shot group in the dirt about 15 paces in front of the target. My wind call was good. Had I opted a 3 mil elevation holdoff, instead of 2, I would have likely connected with a few.
View of target, note hits short of target.
I only found remnants of one bullet. It appears to have hit point first.
The overall "group" on the ground, viewed from the perspective of the trajectory, appears about 12" wide, with one flyer to the right about 24" out. Vertical spread looks like about 24".
Picture of the individual craters are here:
montanamarine/Targets/1850 yards - Page 1 - Photobucket - Video and Image Hosting
To me they look pretty much like they were coming in point first.
When the snow melts and the ground is dry enough to get a dust signature, I'll try this again. Bullet splatters on the steel should be very telling in regards to stability.
lerch
<strong>SPONSOR</strong>
with all my love for the fast and furious long range cartridges it may seem dumb but i own a savage tactical 308 and i love it. great bbl life, great accuracy and just plain fun to shoot. with that said of course i want to push it to its ballistic limit. after spending alot of time on XBAL studying the ballistics of different bullets the answer seemed pretty clear.
with the BC of the Berger 30cal 175gr bullet at 308 speeds it just cant be beat by what i have seen. also it allows you to get to 1K with supersonic velocities. we sell the bergers so i know they are kinda expensive but it does give you the most range and wind bucking ability in the 308 cartridge.
the Amax bullet will probably give you a little better low velocity expansion with its polymer tip but the BC of the Berger still has the edge.
steve
with the BC of the Berger 30cal 175gr bullet at 308 speeds it just cant be beat by what i have seen. also it allows you to get to 1K with supersonic velocities. we sell the bergers so i know they are kinda expensive but it does give you the most range and wind bucking ability in the 308 cartridge.
the Amax bullet will probably give you a little better low velocity expansion with its polymer tip but the BC of the Berger still has the edge.
steve
MontanaMarine
Well-Known Member
The 175 Berger is a fair bullet, but if you run external ballistics on a 175 Berger at 2750 fps, compared to a 208 Amax at 2550 fps, you might be surprised.
In local atmosphere (4500') the 208 retains 1200 fps to 1500 yards, the 175 Berger to 1350 yards. The 208 will have less drift, and more energy, at all ranges. The 175 will save a couple MOA of elevation at 1K (29 vs 31) but that is not a significant advantage to me, once corrections are proven.
In local atmosphere (4500') the 208 retains 1200 fps to 1500 yards, the 175 Berger to 1350 yards. The 208 will have less drift, and more energy, at all ranges. The 175 will save a couple MOA of elevation at 1K (29 vs 31) but that is not a significant advantage to me, once corrections are proven.
milanuk
Well-Known Member
Have you ever played w/ the Berger 210 VLD vs. the 208 AMax? Just curious.
Marine sniper
Well-Known Member
I have two .308's with a 12 twist and some Berger 190's and 210's I will have to try some of those bullets. I have shot a lot of 168's in .308's when I was in the Marine Corps, and was guilty of assuming the .308 would not stabalize the heavier bullets in slower twists than a 10.
I have some 200 AB's I will take for a whirl also.
I have some 200 AB's I will take for a whirl also.
milanuk
Well-Known Member
I have used some 190gr bullets, both SMKs and Bergers, from 1-12" twists just fine. Normally I stick w/ a 155 running fast for my F-Class stuff... but I have to admit I'm curious about the 'heavies'. Usually my barrels (set up more for 155-175gr bullets) are a wee bit short in the throat for the 210gr pills w/o starting to significantly cut into the powder capacity - thats why I was surprised at Shawn's results w/ the 208 stuffed that far into the case.
After reading this thread, I got ta thinking... I *do* have that spare 'take-off' 1-12" twist barrel from my 12 F/TR... if I find a local 'smith w/ a throating reamer (that I trust not to f-ck up a good shooting barrel), perhaps I can set that one up for some testing... I hear lots of promising things about N550 and such behind the heavy bullets.
After reading this thread, I got ta thinking... I *do* have that spare 'take-off' 1-12" twist barrel from my 12 F/TR... if I find a local 'smith w/ a throating reamer (that I trust not to f-ck up a good shooting barrel), perhaps I can set that one up for some testing... I hear lots of promising things about N550 and such behind the heavy bullets.
MontanaMarine
Well-Known Member
Yes, they work well in my 1/12 twist 308 too. Load data and drop is nearly identical. The 208 AMax has a slightly higher BC (.648 vs .640). Berger's website recommends 1/11 twist as optimum for their 210 VLD.
I switched over to the 208s mainly for the price difference.
210 Berger in 308 case:
308Win, 210 Berger, 44.5gr RL15, 5-shots, 100 yards:
I switched over to the 208s mainly for the price difference.
210 Berger in 308 case:
308Win, 210 Berger, 44.5gr RL15, 5-shots, 100 yards:
lerch
<strong>SPONSOR</strong>
I will run the ballistics again but the difference may be our altitude.
in all my exbal runs the 175 berger still beat out the 208 amax, i would rather shoot the 208 for the polymer tip but i will just have to run the test again.
steve
in all my exbal runs the 175 berger still beat out the 208 amax, i would rather shoot the 208 for the polymer tip but i will just have to run the test again.
steve
Marine sniper
Well-Known Member
I just threw together some test loads, 45 and 46 grs. IMR 4831 seated bout .020 off the lands Rem 9 1/2's Berger 210's. Talk about a compressed load LOL.
I will take them out Thursday and see if they will stabalize at 300.
Montana Marine; have you shot any game with the A-Max's or comparred them in accuracy to the 210's. I shoot 210's in my 300 WBY also. I think the 210's would do pretty well on game in my 308 at ranges less than 600 yards.
I am not so sure about the A-Max really having a better BC than the Berger (I know it is advertised as such). With the Berger's secant ogive I would expect it to be higher.
I will take them out Thursday and see if they will stabalize at 300.
Montana Marine; have you shot any game with the A-Max's or comparred them in accuracy to the 210's. I shoot 210's in my 300 WBY also. I think the 210's would do pretty well on game in my 308 at ranges less than 600 yards.
I am not so sure about the A-Max really having a better BC than the Berger (I know it is advertised as such). With the Berger's secant ogive I would expect it to be higher.
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