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Went to the indoor range yesterday just to sight in two of my rifles and put some ladder loads down in AR COMP my 264 LBC 24” BHW 1-8 barrel. I had loaded some Hornady 123gr SST’s and some Hornady 129 gr SST’s. 123’s were loaded to COAL of 2.274 and 129’s were 2.296. Ladder for 123’s were 27.0 through 28.8 grains and 26.2 through 27.6 grains. Once fired brass, CCI 450 primers. It was roughly 72 degrees at the range. Garmin C1 pro chrono<br
The 123 ladders velocities were as follows 27.0 to 28.8 at .2 grain intervals. 2,477 , 2,493, 2,535, 2,537, 2,568, 2,631, 2,622, 2,659, 2,676, 2,720.
129 gr SST Ladder 26.2 to 27.6 gr 2,459, 2,469, 2,504, 2,522, 2,524, 2,550.
I looked at all my case heads as I went up ladders, even at the starting loads my case heads showed slight swipes , even the obviously hot hot load of 28.8 gr with the 123’s were superficial, except for the 28.8 load itself. It was not raised but the primer was really flat and the firing pin hole even has a little flow.
Here are pics of the brass heads and the profile This 24” is only 10 rounds down the tube before this. Yes even off the shelf ammo ( Hornady 100 gr ELD VT ) exhibited slight swipe marks. I do think because it’s a 24” barrel with a standard rifle length gas port some of the swiping is cause because of a dwell timing issue.
In truth, before I bought it should probably have a +2 gas hole location. But Black Hole did not make them this way. I do have an adjustable gas block and I could back it down a little. While it may have a very small impact on it , I believe it can only be addressed with a heavier rifle length buffer. I have a ADB but I have not tuned it yet. These are the first loads down this tube.
I know they are roughly 5.0 oz. I did this with my LR 308 in 308 win and it helped immensely with the dwell time issue. I ordered some tungsten weights, which I should get next week. So any other suggestions would be appreciated on this .
As for my loads, 2,720 fps is crazy for a 123’s. For the 123’s looking at the cases, my thoughts are the 28.8 load is over the top. 28.6 is more tamed but it’s still probably by my guess 60,000 plus chamber pressure. They will still be warm but not crazy.
I’m thinking that 28.3 to 28.5 are loads should shoot for accuracy. One grain increments. So hovering around 2,660 plus or minus. I do have some other straight ladders for the 123 loads with Power Pro Varmint and CFE 223, so I’ll run that first, before I move to accuracy load ladders.
For the 129’s other than the slight swipes the primers look rounded so there is probably a little more room on the top end. But I’m thinking that at 2,550 fps we are probably just about knocking on the door. So probably looking at 2570 fps max on this one.
Once I get a hundred rounds down the tube I’ll shoot the same load in my 20” BHW 1-8 barrel which already has probably 300 rounds down it. My guess is I will be showing a 100 to 110 fps difference for those 4” I’ll keep you posted . Any ideas to increase my dwell time would be appreciated.
Just want to know how far I am over the 52k Sami pressure? . There was no burning on the brass. I tumbled it and full length resized the brass. You can barely see the smears, and the primer pockets seem fine. Necks looked good as well.
The 123 ladders velocities were as follows 27.0 to 28.8 at .2 grain intervals. 2,477 , 2,493, 2,535, 2,537, 2,568, 2,631, 2,622, 2,659, 2,676, 2,720.
129 gr SST Ladder 26.2 to 27.6 gr 2,459, 2,469, 2,504, 2,522, 2,524, 2,550.
I looked at all my case heads as I went up ladders, even at the starting loads my case heads showed slight swipes , even the obviously hot hot load of 28.8 gr with the 123’s were superficial, except for the 28.8 load itself. It was not raised but the primer was really flat and the firing pin hole even has a little flow.
Here are pics of the brass heads and the profile This 24” is only 10 rounds down the tube before this. Yes even off the shelf ammo ( Hornady 100 gr ELD VT ) exhibited slight swipe marks. I do think because it’s a 24” barrel with a standard rifle length gas port some of the swiping is cause because of a dwell timing issue.
In truth, before I bought it should probably have a +2 gas hole location. But Black Hole did not make them this way. I do have an adjustable gas block and I could back it down a little. While it may have a very small impact on it , I believe it can only be addressed with a heavier rifle length buffer. I have a ADB but I have not tuned it yet. These are the first loads down this tube.
I know they are roughly 5.0 oz. I did this with my LR 308 in 308 win and it helped immensely with the dwell time issue. I ordered some tungsten weights, which I should get next week. So any other suggestions would be appreciated on this .
As for my loads, 2,720 fps is crazy for a 123’s. For the 123’s looking at the cases, my thoughts are the 28.8 load is over the top. 28.6 is more tamed but it’s still probably by my guess 60,000 plus chamber pressure. They will still be warm but not crazy.
I’m thinking that 28.3 to 28.5 are loads should shoot for accuracy. One grain increments. So hovering around 2,660 plus or minus. I do have some other straight ladders for the 123 loads with Power Pro Varmint and CFE 223, so I’ll run that first, before I move to accuracy load ladders.
For the 129’s other than the slight swipes the primers look rounded so there is probably a little more room on the top end. But I’m thinking that at 2,550 fps we are probably just about knocking on the door. So probably looking at 2570 fps max on this one.
Once I get a hundred rounds down the tube I’ll shoot the same load in my 20” BHW 1-8 barrel which already has probably 300 rounds down it. My guess is I will be showing a 100 to 110 fps difference for those 4” I’ll keep you posted . Any ideas to increase my dwell time would be appreciated.
Just want to know how far I am over the 52k Sami pressure? . There was no burning on the brass. I tumbled it and full length resized the brass. You can barely see the smears, and the primer pockets seem fine. Necks looked good as well.
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