![]() ![]() Make sure the Miller number is at least 2.0 and the velocity is below the speed of sound. Run the numbers for the coldest temperature you plan to shoot in. You want to be a bit under (at least 50 fps.) to account for variation in velocity. JBM's regular calculator will tell you the speed of sound for whatever temperature you enter for the load: Although, some people say that the bullet is more likely to tumble after impact if it is around 1.7ish You want it to be above 2.0 for subsonic loads. JBM has a calculator for the miller stability number: give you a good crack when theres snow on the ground. A bullet that is subsonic in hot weather may not be in cold weather because the speed of sound decreases. A bullet that stabilizes in hot weather, may not stabilize when it's cold out. And temperature is important if it snows where you live. It's not as much bullet weight as bullet length. Originally Posted By: Gunfighter14e2Don't think in terms of chambering,(until past 30-06 case size) think in twist rate, bullet weight, an exit speed. Normally 1-7 will handle 240s with no issues.Re: Heaviest. We had a Rem 700 in 300 blackout with a 1-7 twist and it won't stabilize 200gr bullets. There are some calculators that say they can figure twist rates for subsonics and probably they work for most but you will have to figure what really works for your rifle by testing. With heavier bullets your velocity will come down and stability will drop. Start with a bullet that is on the light end to insure it will stabilize and as you get your powder charge close to 1100fps then bump up the bullet weight a little at time til you find the one that starts hitting a little sideways at 100yds. Such a bullet, however, would produce the worst possible terminal ballistics. The ideal bullet shape, from an aerodynamics perspective, is something like a football. An abrupt rear surface also causes turbulence. Most of us have stuck one or more in our time playing with them. An abrupt front surface (full wadcutter or backwards bullet) causes turbulence. ![]() Unlike loading for the highest velocity you need to be careful of not having enough to get the bullet out the end of the barrel. I think you may have to fiddle with your loads in the 7mm to come up with a subsonic load that works for you. 308 so once again its all up to what you want. Shooting 240gr 30 cal bullets subsonic gives you a lot more energy than shooting 125s out of a. the round the barrel slides backwards with the bolt for a short distance. This is one reason the 300 blackout type stuff has a lot of followers. Standard loading for the ShAK-12 is a lightweight, subsonic ammunition with an. Another guy at the range who had a suppressor said he had heard you could load a bullet backwards and get more stability. Shoot 100 different bullets at the same speed and the heaviest one wins on energy. Joined:Sat 1:44 pm Location:North, Ga Loading bullet backwards Postby JDSquire Mon 1:49 am I was at the range today checking some SS loads for stability.they were keyholing. Long grooves in its gilding metal jacket. The Sub-X bullet used in Subsonic Rifle features a lead core. Subsonic Handgun utilizes tried-and-true XTP® bullets that expand reliably at subsonic velocities. ![]() Everytime you drop bullet weight you lose energy since you're limiting the velocity to something under 1100fps. Hornady® Subsonic Ammunition designed for accuracy and performance below the speed of sound now comes in both rifle and handgun loads. However since everyone isn't trying to get max performance from their bullet with the lowest sound levels its up to you what you try. I think the quiet thing is why most folks are shooting inappropriate bullets subsonic. Trail boss is a pretty poor choice for accuracy too as most of them will likely tell you as well. Most of the guys doing it with 308 either have fast twist barrels or they're shooting light bullets and missing the whole point too. ![]()
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