Posted By: J.G.
7mm-08 A.I. continues to impress. - 03/07/18 05:59 PM
My little 17" walking around rifle has a good load with 162 gr. ELD-X, at a muzzle velocity of 2640 fps on formed brass. Just because I wanted to know, I decided to work up a load with 150 gr ELD-X. I wanted to know how fast they would go out of such a short barrel, and I wanted to see if the incredible (for weight and length) BC was legit. Sunday I ladder tested them, searching for pressure. Keep in mind, standard 7mm-08 data is at your fingertips, but Ackley Improved data is not necessarily. I had to keep stepping up until I saw pressure signs on the brass. Well, I saw a node beginning, but kept going, and finally got hard bolt lift, and a shiny ring around the primer pocket, it got out of the node, so no worries, but I did find pressure.
Tuesday was time to group shoot the three charges that were in the node, and right before pressure. There was one clear winner with a vertical dispersion of 13/16" at 300 yards. I reproduced that load, and headed to the 800 yard range. I guessed at an MV of 2700 fps, and plugged that into the ballistic calculator. It center punched every steel out to 800 yards. So the BC and the MV seem to be correct. I am normally the guy that runs heavy, high BC bullets, but this lighter one, the rifle seems to like better. I checked the energy delivery out to 500 yards, and the increase in velocity looks to be delivering the same energy as the big 162's going 60 fps slower, at the muzzle.
My rental rifle is a standard 7mm-08, and it too shoots 162 A-maxes at 2640 fps MV, but it has a 3" longer barrel.
I found a legitimate 120 fps gain in velocity, shooting 162's out of 24" barrels, on two rifles last summer. That gain was from unformed brass, to formed brass with more powder. In my opinion it is the highest performance cartridge that will fit that action. It cheats wind like a 6.5mm, but hits much harder. Recoil is negligible, the case is just flat out efficient!
Tuesday was time to group shoot the three charges that were in the node, and right before pressure. There was one clear winner with a vertical dispersion of 13/16" at 300 yards. I reproduced that load, and headed to the 800 yard range. I guessed at an MV of 2700 fps, and plugged that into the ballistic calculator. It center punched every steel out to 800 yards. So the BC and the MV seem to be correct. I am normally the guy that runs heavy, high BC bullets, but this lighter one, the rifle seems to like better. I checked the energy delivery out to 500 yards, and the increase in velocity looks to be delivering the same energy as the big 162's going 60 fps slower, at the muzzle.
My rental rifle is a standard 7mm-08, and it too shoots 162 A-maxes at 2640 fps MV, but it has a 3" longer barrel.
I found a legitimate 120 fps gain in velocity, shooting 162's out of 24" barrels, on two rifles last summer. That gain was from unformed brass, to formed brass with more powder. In my opinion it is the highest performance cartridge that will fit that action. It cheats wind like a 6.5mm, but hits much harder. Recoil is negligible, the case is just flat out efficient!
