04-28-2020, 03:07 PM
VASCAR2 Wrote:There isnt a lot of difference in velocity with typical 120-125 grain and 129-130 grain hunting bullets in barrels of 18 compared to 20 in 6.5 Grendel. If you use a bullet like the 129 grain Nosler Accu Bond Long Range (ABLR) it expands down to 1300 FPS where many bullets need from 1800 to 2000 FPS to expand depending on projectile. In many cases your looking at approximately 25-50 yards more hunting distance with a 20 barrel compared to a 18 barrel. Elevation and particular hunting bullet with ballistic coefficient and velocity have a bearing on effective range on your particular hunting ammo.
Whether you hunt with a suppressor might dictate a desire for a shorter barrel. Thick wooded terrain or mountainous areas can also dictate which barrel length is more suitable for your area of hunting.
Here are some chronograph results I obtained which will give you an indication of velocities for particular 6.5 Grendel barrel lengths. Lilja, Criterion and Wilson all get very good reviews and can usually be ordered without a delay in shipping. For rack grade barrels Alexander Arms get good reviews as do several other brands. If your interested in accuracy I think it is wise to spend money on a quality barrel.
12 6.5 Grendel chronograph results
12 PSA SS with LabRadar.
123gr Hornady American Gunner bulk HPBT = 2201 FPS ave with SD of 14.7 (2" to 2.55" groups)
123gr Hornady ELD-M Black = 2265 FPS ave with SD of 13.2 (1.4 to 1.7" groups)
123gr Hornady Custom SST Factory= 2277 ave with SD of 11.8 (2.9 to 3.2" groups)
12 Faxon
Wolf steel case at 2364 Avg. SD was 9.7.
Here is a list of the tested ammo by average velocity for each barrel length. These results were achieved using a Magnetto Speed chronograph in 2016 on a 70-75 degree day. The PPU ammo is older ammo loaded with large rifle primers and has since been recalled by the manufacturer.
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
Hand Load 107 Grain SMK 28.5 IMR8208XBR, CCI 41 Hornady cases.
20" 2658
24" 2729
Hornady 123 grain American Gunner
12 2201
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
This is all excellent data. I've been looking for a list like this for comparison on barrel lengths, can you tell us what brand barrels you tested on the 18" and 20" and if that should make a substantial difference? I've got a 20" Criterion from PF and an "18 in Criterion coming(also PF). The 20 shoots better than me and I anticipate the the same results from 18". I don't reload so I'm stuck with factory ammo, but that's not so bad either(Hornady 123ssts). I was figuring on 2450 FPS from the 18" and maybe a little less than the advertised .510 BC from Hornady's website. If I were going to use their ballistic calculator, what numbers would get me close with the 123ssts?