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[VASCAR2]

Welcome to the forum jmda! I second the recommendation for a 18” Wilson Combat or 16” Grendel Monster Logo manufactured by Green Mountain. I got these results using a Magnettospeed chronograph a few years ago but this will give you an indication the velocity difference of an 18” barrel compared to a 16” 6.5 Grendel barrel. The choice of bullet can make a significant difference in the expansion of the bullet at different range. The 123 grain SST and 120 grain Nosler Ballistic expand down to 1800 FPS. The 129 grain Nosler ABLR expands down to 1300 FPS. I just checked the Hornady Ballistic calculator and a 123 grain SST at 2430 FPS at 400 yards is 1813 FPS 897 ft pounds of energy. For me I consider 400 yards my maximum range with a 16” or 18” 6.5 Grendel for medium game at 450’ ASL. I used 0’ ASL when using the Hornady Ballistic calculator.


Here is a list of the tested ammo by average velocity for each barrel length.

120 Grain HP BT PPU

16" 2392

18" 2455

20" 2480

24" 2559

110 grain FMJ PPU

16" 2510

18" 2570

20" 2614

24" 2683

123 grain A-Max Hornady

12” 2265 (123 grain ELD-M)

16" 2419

18" 2464

20" 2505

24" 2568

123 Grain SST Hornady

12” 2277

16" 2430

18" 2493

20" 2511

24" 2583

Hand Load 123 Grain Nosler CC, 31.0 grains CFE223, CCI 450

16" 2449

18" 2471

20" 2526

24" 2619

100 Grain FMJ Wolf

12” 2364

16" 2507

18" 2571

20" 2615

24" 2695


Here is the difference between the 18” barrel compared to the shorter 16” barrel which was slower with every load.

120 grain PPU HP BT

63 FPS difference

110 grain PPU FMJ

60 FPS difference

123 grain A-Max

45 FPS difference

123 grain SST

63 FPS difference

Hand load 123 grain Nosler CC

27 FPS difference

Wolf 100 grain FMJ Steel cased

64 FPS difference