WHOA! The 6x150mm Howitzer is always an option.
I built a 6.5x06. Would build that again, but with a name brand barrel with a better twist to stabilize the 140 AMax's. Throat it correctly and I believe you might have what you are looking for.
I would HIGHLY recommend coating the bullets with Danzac/WS2 or HBN (have not tried HBN yet).
The 338 RUM that I built for my shooting buddy still has a LOT of life left in the 32" Rock barrel. Has just over 1000 rounds down the tube and still going strong.
Would go pick a bullet that has a HUGE B.C. and then shove it into an '06 or Win Mag case. The 6.5/264 bullets have huge B.C. and the 7/.284 are just a touch behind them. There is a bit more bullet selection for the 6.5/.264 bullets. The 140 AMax is almost or just over 1.5" in length. If you added stabilizing fins to the boat tail....believe you might have NASA calling you.
There is also the 22/6mm AI (a.k.a. "Half mile 22"). Have not stretched the legs on mine yet...but 75 gr AMax's do rather well at 3950 fps.
This link might help you decide:
http://www.hornady.com/ballistics-re...ics-calculator
For the 75 gr AMax at 3950 fps (16.1 MOA at 1000 yds with a 100 yd zero):
75 gr AMax at 3950
75 gr., .435 B.C. www.hornady.com
Range (yards) Muzzle 100 200 300 400 500 600 700 800 900 1000
Velocity (fps) 3950 3678 3424 3184 2957 2741 2536 2339 2152 1973 1804
Energy (ft.-lb.) 2598 2253 1952 1688 1456 1251 1071 911 771 648 542
Trajectory -1.5 0.0 -1.1 -5.1 -12.5 -23.9 -39.9 -61.2 -89.0 -124.2 -168.4
Come Up in MOA -1.5 0.0 0.5 1.6 3.0 4.6 6.3 8.4 10.6 13.2 16.1
13.3 MOA for 1000 yds with 100 yd zero
140 gr AMax at 3100 140 gr., .585 B.C. www.hornady.com
Range (yards) Muzzle 100 200 300 400 500 600 700 800 900 1000
Velocity (fps) 3950 3746 3552 3367 3190 3020 2856 2698 2546 2399 2257
Energy (ft.-lb.) 4850 4363 3922 3524 3162 2834 2535 2263 2015 1789 1583
Trajectory -1.5 0.0 -1.0 -4.7 -11.4 -21.6 -35.5 -53.7 -76.7 -104.9 -139.2
Come Up in MOA -1.5 0.0 0.5 1.5 2.7 4.1 5.7 7.3 9.2 11.1 13.3
In the 6.5x55 AI's that I built, we are at 3050 fps with H4831. Have NOT tried RL17 yet - should get to the 3100 fps without pressure issues...and a little more. :) An '06 case might do better, might not. Trade off between case fill, powder burn rate, ability to light the powder, blah, blah.
338 caliber 300 gr SMK at 3000 fps (STILL has 2385 ft lbs of energy at 1000 yards!!!!!) - you WILL need a muzzle brake to shoot it:
300 gr SMK 338 caliber 300 gr., .768 B.C. www.hornady.com
Range (yards) Muzzle 100 200 300 400 500 600 700 800 900 1000
Velocity (fps) 3000 2875 2754 2636 2522 2410 2301 2194 2091 1990 1892
Energy (ft.-lb.) 5995 5507 5053 4630 4235 3868 3525 3207 2911 2638 2385
Trajectory -1.5 0.0 -2.7 -9.9 -22.2 -39.8 -63.5 -93.7 -131.1 -176.6 -230.8
Come Up in MOA -1.5 0.0 1.3 3.2 5.3 7.6 10.1 12.8 15.7 18.7 22.0
Berger's new 300 gr 338 caliber bullet is supposed to have .841 B.C....so.....:
You only gain 7 inches of drop at 1K yards over the SMK - don't think the cost is there for the difference at 1K yards - you will be dialing up anyway. :)
300 gr Berger Hybrid 338 caliber 300 gr., .841 B.C. www.hornady.com
Range (yards) Muzzle 100 200 300 400 500 600 700 800 900 1000
Velocity (fps) 3000 2886 2775 2667 2561 2458 2357 2258 2162 2068 1977
Energy (ft.-lb.) 5995 5548 5130 4737 4369 4024 3701 3398 3114 2850 2603
Trajectory -1.5 0.0 -2.7 -9.8 -21.8 -39.1 -62.1 -91.4 -127.5 -171.1 -222.7
Come Up in MOA -1.5 0.0 1.3 3.1 5.2 7.5 9.9 12.5 15.2 18.1 21.3
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