With all the supply issues they are currently on order. I can understand if you want an 18 barrel but for hunting a 16 barrel can be used from 300 yards and in quite effectively. Here is the velocity difference I got for an 18 Brownells SS 5R 1:8 twist barrel and my J&T 16 1:9 twist CMV barrel with a Magnettospeed chronograph.
Im not trying to convince you to buy the 16 barrel but to let you see the difference in velocity for different barrel lengths. I enjoyed building AR-15s and I have several. I was just trying to give you another option. There are more barrel options today than ten to twelve years ago for AR-15 barrels in 6.5 Grendel.
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
16" 2419
18" 2464
20" 2505
24" 2568
123 Grain SST Hornady
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
16" 2507
18" 2571
20" 2615
24" 2695
Hand Load 107 Grain SMK 28.5 IMR8208XBR, CCI 41 Hornady cases.
20" 2658
24" 2729
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
Difference between 20 and 18 barrel 6.5 Grendel
120 grain PPU HP BT
25 FPS difference
110 grain PPU FMJ
44 FPS
123 grain A-Max
41 FPS difference
123 grain SST
18 FPS
Hand load 123 grain Nosler CC
55 FPS difference
Wolf 100 grain FMJ Steel Cased
44 FPS difference
Difference between 24" and 20"
PPU 120 grain HB BT
79 FPS
PPU 110 grain FMJ
69 FPS
123 grain A-Max, Hornady
63 FPS
123 grain SST, Hornady
72 FPS
Hand Load 123 grain Nosler CC, 31.0 grains CFE223, CCI 450
93 FPS
100 grain FMJ Wolf
80 FPS
Hand Load 107 grain SMK 28.5 grains IMR8208XBR, CCI 41
71 FPS
Im not trying to convince you to buy the 16 barrel but to let you see the difference in velocity for different barrel lengths. I enjoyed building AR-15s and I have several. I was just trying to give you another option. There are more barrel options today than ten to twelve years ago for AR-15 barrels in 6.5 Grendel.
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
16" 2419
18" 2464
20" 2505
24" 2568
123 Grain SST Hornady
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
16" 2507
18" 2571
20" 2615
24" 2695
Hand Load 107 Grain SMK 28.5 IMR8208XBR, CCI 41 Hornady cases.
20" 2658
24" 2729
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
Difference between 20 and 18 barrel 6.5 Grendel
120 grain PPU HP BT
25 FPS difference
110 grain PPU FMJ
44 FPS
123 grain A-Max
41 FPS difference
123 grain SST
18 FPS
Hand load 123 grain Nosler CC
55 FPS difference
Wolf 100 grain FMJ Steel Cased
44 FPS difference
Difference between 24" and 20"
PPU 120 grain HB BT
79 FPS
PPU 110 grain FMJ
69 FPS
123 grain A-Max, Hornady
63 FPS
123 grain SST, Hornady
72 FPS
Hand Load 123 grain Nosler CC, 31.0 grains CFE223, CCI 450
93 FPS
100 grain FMJ Wolf
80 FPS
Hand Load 107 grain SMK 28.5 grains IMR8208XBR, CCI 41
71 FPS