Post by bluedot on Dec 9, 2022 22:21:29 GMT -5
The CFE BLK is pushing the bullet supersonic and I want subsonic, NOT supersonic. I want to have the gun set up for both super and sub. Look at the FPS reading again. What FPS is subsonic? A MV of 1050 give or take, correct?
But what I was talking about aligns with what Dr. Henley mentioned. Personally I think you might be better off trying a heavier bullet.
Something's off with your load, as a .300blk is subsonic with a 198gr bullet at 12.5gr of CFEBLK, and that's a compressed load in a smaller case than you're using. Something doesn't add up. Your load should be generating even lower pressures.
Wait, you're using a bolt-action rifle, right? That could be part of it. This is spitballing again, but CFEBLK is designed to work in a gas-operated weapon. It is designed to create enough gas to operate the action, and due to the semi-automatic nature of those weapons, it bleeds more gas out of the chamber as it cycles, right?
So... it's entirely possible that you'd need a very light charge to be subsonic in a bolt-action .308.
BUT... I could be wrong entirely and you should just buy a .300blk and forget it.
Wasn't there someone a few years ago who posted about having issues with using charges that didn't fill the case, and when he used a different powder that filled the case his pressure issues stopped?
Part of the issue is the bolt gun has a 1:10 twist. I could stabilize the heavier but longer alloy bullets then, but I can't with the 1:10 twist. I can stabilize a 190 grain cup and core bullet like the Hornady Sub-X but not the all copper bullets of the same weight due to their length. I can't even stabilize the 175g Lehigh #05308175CuSP Controlled Chaos Copper Bullet but I can stabilize the 176g Lehigh #02308176LP Controlled Fracturing (Subsonic) bullet. Probably due to the bullet shape. The Controlled Chaos Copper Bullet has a much greater tapered ogive. That bullet is 1.420" long vs. the 1.240" length of the 175g Controlled Chaos Copper Bullet. The 190g Sub-X bullet is 1.260" in length.
I would go get a .300 BLK if you can put together a build list for me that will weigh 4 lb 13 oz That's what this bolt action rifle weighs without the scope and sling. That is with the 22" barrel.
Here are the bullets that I've played with. From right to left: Hornady Sub-X, Lehigh 176g Controlled Fracturing (Subsonic), Lehigh 175g Controlled Chaos Copper Bullet, and Lehigh 194g Maximum Expansion Subsonic # 01308194LP. Only the first two bullets will stabilize in the bolt gun.