Larryh128
Silver $$ Contributor
I've been playing a little with my AR-10 that I swapped out the 308 barrel for a Faxon 20" 5c nitrided 6.5 Creedmoor barrel. I used 4350 for the deer season because there was a bunch of easy info and I needed a load fast. Accuracy was good but velo was slow. Still did the job on a couple deer using Barnes 127gr LRX. We did a small test yesterday in "ideal" conditions of 18 degrees and gusting 20 mph plus winds using RL-16. It caught my attention because it's temp stable and has an anti-copper agent as well. This is what I learned in my barrel making big jumps on powder. I was using Hornaday 129 gr SST's because the are cheap and fairly accurate for testing.
40 grs = 2550 fps
41 grs = 2620
42 grs = 2706
43 grs = 2803
44 grs = 2820
43 grs was all the 20" barrel could burn effectively. I would not shoot 44 grs in the AR and didn't shoot them for a group. My friends RPR shot them very well with much higher velo out of the longer barrel. We really didn't see a difference in velo between the 2 rifles until we hit 44 grs. The RPR could easily go higher than 44 grs without pressure but shot very well at that charge. My AR shot a sub- half inch group at 100 with the 43 gr load in those conditions. I was using a Burris XTR 1.5x8 set at 8 power so bigger glass would probably do better. Still I consider this good accuracy out of an AR-10 platform. My guess is that I'll be in the upper 42's with the Barnes 127 LRX bullet. Obviously this isn't a complete test but a good indication of what the powder/load will do. It was about all the cold we could stand.
40 grs = 2550 fps
41 grs = 2620
42 grs = 2706
43 grs = 2803
44 grs = 2820
43 grs was all the 20" barrel could burn effectively. I would not shoot 44 grs in the AR and didn't shoot them for a group. My friends RPR shot them very well with much higher velo out of the longer barrel. We really didn't see a difference in velo between the 2 rifles until we hit 44 grs. The RPR could easily go higher than 44 grs without pressure but shot very well at that charge. My AR shot a sub- half inch group at 100 with the 43 gr load in those conditions. I was using a Burris XTR 1.5x8 set at 8 power so bigger glass would probably do better. Still I consider this good accuracy out of an AR-10 platform. My guess is that I'll be in the upper 42's with the Barnes 127 LRX bullet. Obviously this isn't a complete test but a good indication of what the powder/load will do. It was about all the cold we could stand.
