MontanaMarine
Well-Known Member
This might be of interest to the 308Win shooters.
Bought the 208s primarily for the 30-06. Figured I'd give them a whirl in the 308, even though I kinda expected stability issues at relatively low MV, and 1/12 twist. Here's what I found:
Load:
Brass: Win
Bullet: 208gr AMax, moly'd
Powder: RL15, 44.5gr
Primer: CCI 200
OAL 2.90"
MV: 2480 fps
Rifle:
Rem factory bbl/chamber 700 VS cut to 22"
1/12 twist
A5 stock
Leupold MK4 3.5-10x40 M1, GenII mildot from Premier Reticles
Badger Ord hardware
Did some 100 yard shots to get a zero. It was windy, but all looked fairly good, at sub-moa.
Went out to 560 yards to see if stability would be an issue at midrange. Results were sub-moa, at about 20F, in 5-15 winds from 9 0'clock.
Here's a pic of the 560 yd results:
Stretched it out to 1120 yards in 15-25 mph wind from between 1 and 2 o'clock (About half-value). Temp 35F.
Took a couple rounds to get on steel. I was at 40 moa up, and 7 moa right. I put 10 downrange. 6 hits, 4 misses left (wind wasn't my friend). The black square is 5" by 5" at the outside edges. I'm kinda surprised it was stable out to this distance, at 1/12 twist, 2480 fps MV.
Here's a pic of the 1120 yard target:
Did more load development using W760 to maximize velocity. Here's the meat and potatoes,
Moly'd 208 AMax
Win brass
W760
50.0gr
2560 fps
22" barrel
OAL 3.002"
That OAL gives a .002" crush on chambering.
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 interesting, 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".
Shot the 50gr W760, 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 - 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.
Bought the 208s primarily for the 30-06. Figured I'd give them a whirl in the 308, even though I kinda expected stability issues at relatively low MV, and 1/12 twist. Here's what I found:
Load:
Brass: Win
Bullet: 208gr AMax, moly'd
Powder: RL15, 44.5gr
Primer: CCI 200
OAL 2.90"
MV: 2480 fps
Rifle:
Rem factory bbl/chamber 700 VS cut to 22"
1/12 twist
A5 stock
Leupold MK4 3.5-10x40 M1, GenII mildot from Premier Reticles
Badger Ord hardware
Did some 100 yard shots to get a zero. It was windy, but all looked fairly good, at sub-moa.
Went out to 560 yards to see if stability would be an issue at midrange. Results were sub-moa, at about 20F, in 5-15 winds from 9 0'clock.
Here's a pic of the 560 yd results:
Stretched it out to 1120 yards in 15-25 mph wind from between 1 and 2 o'clock (About half-value). Temp 35F.
Took a couple rounds to get on steel. I was at 40 moa up, and 7 moa right. I put 10 downrange. 6 hits, 4 misses left (wind wasn't my friend). The black square is 5" by 5" at the outside edges. I'm kinda surprised it was stable out to this distance, at 1/12 twist, 2480 fps MV.
Here's a pic of the 1120 yard target:
Did more load development using W760 to maximize velocity. Here's the meat and potatoes,
Moly'd 208 AMax
Win brass
W760
50.0gr
2560 fps
22" barrel
OAL 3.002"
That OAL gives a .002" crush on chambering.
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 interesting, 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".
Shot the 50gr W760, 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 43.74I 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 - 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.
