![]() ![]() VERY quiet, all you hear is the bullet impacting the berm. Using a 180 grain Sierra RN bullet over Federal FLS/annealed brass with GM210M primers out of a 26 inch barrel Rem 700 PSS with 12" twist 10.7 gns is giving meġ041 fps, with an SD of 10.5. I backed off to 10.5, 10.7, etc, to 11.1 grain by 0.2 grain intervals. I did the Trailboss calculation based on bullet/case volume. I use both with a Gemtech Sandstorm suppressor. They were $4 per case since they're CNC machined from bar stock.Ī better solution in my opinion is to have two rifles,one subsonic only, the other supersonic only. In the past I've seen them for sale but haven't found them recently. You may be able to find reduced capacity 308 Win cases suitable for subsonic loads. The second problem of using a dual purpose subsonic/supersonic 308 Win is that its very difficult to get good velocity consistency (SD) with 56 grain case capacity using the tiny powder charge needed to drive bullets to 1000 fps. You'll more than pay for the barrel with the first suppressor you destroy. The speed of sound is 1052 fps at 0F, 1107 fps at 50F, and 1160 fps at 100F. A bullet that's stable at 1025 fps at room temperature can be very unstable in cold weather. Shooting heavier bullets is desirable for the added energy. ![]() With a bullet at only 35% of the normal velocity it has under 13% of the normal energy. All bullets are least stable around the speed of sound, with a "sweet spot" of better stability around 50 to 100 fps less than the speed of sound. Stability for a given bullet depends not only on twist but also on air density and velocity. Yes, You can get a 12:1 barrel to stabilize some bullets at subsonic velocities. If you must have a 308 Win rifle that can shoot subsonic and supersonic consider this barrel: 308 subs stabilize in a 1-12 barrel? I have a 700 p that I am cutting down to 18in and what to shoot subsonic ammo when I get my suppressor. ![]()
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