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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
375 H&H for long range
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<blockquote data-quote="benchracer" data-source="post: 957680" data-attributes="member: 22069"><p>My CZ 550 is in its original configuration. The barrel band front sight, underbarrel recoil lug and magazine box are unaltered. With an OAL of 4.040", the 350g SMK loads are a single feed proposition. Given their long range potential, I am fine with that. I have been working mainly with 300g bullets, so I haven't gotten to accuracy testing with the 350's yet. So far, I have only done workups intended to establish pressure and velocity limits with the 350g SMK. Accuracy work is yet to come. I need to have some bedding work done on my rifle before I continue my testing (I noticed yesterday that the barrel is contacting the forearm).</p><p> </p><p>With 300g SGK's and RL-17 loaded to 3.785" (which WILL feed from the magazine of my CZ 550), the 10 shot average velocity came in at 2780. That load grouped into 1.1" @ 100 yards (not bad for a rifle with bedding issues) and should have a trajectory very similar to .308 175g SMK match ammo. This load shot without pressure signs at 75* air temps, but gave me sticky bolt lift at 85*, so it is on the ragged edge of pressure limits. I would not be afraid to use it during fall hunting season in the states, but I wouldn't take it to Africa.</p><p> </p><p>I had previously done pressure and velocity runups with the 350g SMK and H4350, RL-17, and H4831. I was getting max velocities of 2400, 2435, and 2300 respectively. With RL-17, the combination acted like it wanted a slower powder. But, the lower velocity obtained with H4831 appeared to suggest that slower powders wouldn't work.</p><p> </p><p>After buying Quickload, I took some case volume measurements and started looking for answers to my questions. Quickload suggested that RL-22 and IMR 7828 SSC would produce the best velocities with the 350g SMK loaded long in the 375 H&H. Quickload predicted 2550 fps from my rifle. Actual shooting with 85* air temps produced velocities of 2601 to 2648 fps with my max loads without pressure signs of any kind. If I can get these bullets to shoot, I may forget all about the 300g bullets.</p></blockquote><p></p>
[QUOTE="benchracer, post: 957680, member: 22069"] My CZ 550 is in its original configuration. The barrel band front sight, underbarrel recoil lug and magazine box are unaltered. With an OAL of 4.040", the 350g SMK loads are a single feed proposition. Given their long range potential, I am fine with that. I have been working mainly with 300g bullets, so I haven't gotten to accuracy testing with the 350's yet. So far, I have only done workups intended to establish pressure and velocity limits with the 350g SMK. Accuracy work is yet to come. I need to have some bedding work done on my rifle before I continue my testing (I noticed yesterday that the barrel is contacting the forearm). With 300g SGK's and RL-17 loaded to 3.785" (which WILL feed from the magazine of my CZ 550), the 10 shot average velocity came in at 2780. That load grouped into 1.1" @ 100 yards (not bad for a rifle with bedding issues) and should have a trajectory very similar to .308 175g SMK match ammo. This load shot without pressure signs at 75* air temps, but gave me sticky bolt lift at 85*, so it is on the ragged edge of pressure limits. I would not be afraid to use it during fall hunting season in the states, but I wouldn't take it to Africa. I had previously done pressure and velocity runups with the 350g SMK and H4350, RL-17, and H4831. I was getting max velocities of 2400, 2435, and 2300 respectively. With RL-17, the combination acted like it wanted a slower powder. But, the lower velocity obtained with H4831 appeared to suggest that slower powders wouldn't work. After buying Quickload, I took some case volume measurements and started looking for answers to my questions. Quickload suggested that RL-22 and IMR 7828 SSC would produce the best velocities with the 350g SMK loaded long in the 375 H&H. Quickload predicted 2550 fps from my rifle. Actual shooting with 85* air temps produced velocities of 2601 to 2648 fps with my max loads without pressure signs of any kind. If I can get these bullets to shoot, I may forget all about the 300g bullets. [/QUOTE]
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375 H&H for long range
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