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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
375 Caliber A-max...might be a possibility. Please read.
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<blockquote data-quote="benchracer" data-source="post: 897382" data-attributes="member: 22069"><p>I tried the 350g SMK in my H&H with a 25" barrel. I don't remember the exact COAL I loaded to. I measured to the rifling and backed off .040". Final COAL was north of 3.9". </p><p></p><p>With load data obtained from Sierra, I tried H 4831 and H4350. I also tried RL-17 using H4350 data. 76 grains of H4831 yielded a compressed load that topped out just a hair over 2300 fps. </p><p></p><p>72 grains of H4350 was very near 100% load density and topped out at just over 2400 fps. There was still some throttle left, but I don't think I could have gotten much above 2450 fps. </p><p></p><p>72 grains of RL-17 still left a lot of room in the case. From the starting load of 68 grains, velocities jumped up very quickly. 70 grains produced mid 2430's. 71 grains produced a DROP of about 50 fps, which I understand to be the telltale warning sign with RL-17 that safe pressures are being exceeded. So, in this instance, RL-17 behaved like a faster powder than H4350. I would consider 70 grains to be the max load with RL-17 and 350g SMK's in my rifle.</p><p></p><p>I only shot these test rounds over a chrono. I didn't put them on paper, so I don't know for sure if they were properly stabilized in my 12 twist barrel. However, the bullets produced deep, straight line penetration several FEET into a dirt bank about 50 yards away that I was using as a back stop. That tends to indicate to me that the bullets were indeed stable. IIRC, the 350 grain SMK is about 1.750" long. When I plug that information into a stability calculator, it spits out a stability factor of 1.713, which means this bullet is easily stabilized in a 12 twist.</p><p></p><p>If one had the barrel throated specifically for the 350 SMK, it might be possible to seat the bullet out far enough to pick up some velocity, but I don't believe it would be enough to be useful. This bullet only yields an .805 g1 bc down to 2200 fps, after which the bc falls off pretty quickly. Launched from the smaller cased .375's, this bullet is going to spend most of its time in a velocity range that yields a .720 g1 bc. Based on its drag characteristics and its thick jacket, this bullet really is built for SPEED. It is sexy, but just doesn't offer much when launched from the smaller cases.</p><p></p><p>The Cutting Edge bullets I am shooting have a higher bc and I can launch them 300 fps faster than the SMK's. I just can't afford to shoot them all the time. A lighter cup and core bullet with a .550 to .650 g1 bc would perform well enough from my rifle to allow for affordable practice at extended range. I could then use the CE's to polish my skills that last little bit and would load them when I carry my rifle afield for more serious purposes.</p><p> </p><p> UPDATE: After running the tested velocities from my rifle with the 350 SMK through JBM, I am intrigued. At sea level, with a muzzle velocity of 2450 fps, it stays above the transonic range past 1100 yards and stays supersonic past 1500 yards. If someone made a bullet like this that would actually expand, it could be useful as a hunting round. As is, I may actually use this bullet as a practice round. I will have to work with it some and see if I can get it to shoot accurately in my rifle.</p></blockquote><p></p>
[QUOTE="benchracer, post: 897382, member: 22069"] I tried the 350g SMK in my H&H with a 25" barrel. I don't remember the exact COAL I loaded to. I measured to the rifling and backed off .040". Final COAL was north of 3.9". With load data obtained from Sierra, I tried H 4831 and H4350. I also tried RL-17 using H4350 data. 76 grains of H4831 yielded a compressed load that topped out just a hair over 2300 fps. 72 grains of H4350 was very near 100% load density and topped out at just over 2400 fps. There was still some throttle left, but I don't think I could have gotten much above 2450 fps. 72 grains of RL-17 still left a lot of room in the case. From the starting load of 68 grains, velocities jumped up very quickly. 70 grains produced mid 2430's. 71 grains produced a DROP of about 50 fps, which I understand to be the telltale warning sign with RL-17 that safe pressures are being exceeded. So, in this instance, RL-17 behaved like a faster powder than H4350. I would consider 70 grains to be the max load with RL-17 and 350g SMK's in my rifle. I only shot these test rounds over a chrono. I didn't put them on paper, so I don't know for sure if they were properly stabilized in my 12 twist barrel. However, the bullets produced deep, straight line penetration several FEET into a dirt bank about 50 yards away that I was using as a back stop. That tends to indicate to me that the bullets were indeed stable. IIRC, the 350 grain SMK is about 1.750" long. When I plug that information into a stability calculator, it spits out a stability factor of 1.713, which means this bullet is easily stabilized in a 12 twist. If one had the barrel throated specifically for the 350 SMK, it might be possible to seat the bullet out far enough to pick up some velocity, but I don't believe it would be enough to be useful. This bullet only yields an .805 g1 bc down to 2200 fps, after which the bc falls off pretty quickly. Launched from the smaller cased .375's, this bullet is going to spend most of its time in a velocity range that yields a .720 g1 bc. Based on its drag characteristics and its thick jacket, this bullet really is built for SPEED. It is sexy, but just doesn't offer much when launched from the smaller cases. The Cutting Edge bullets I am shooting have a higher bc and I can launch them 300 fps faster than the SMK's. I just can't afford to shoot them all the time. A lighter cup and core bullet with a .550 to .650 g1 bc would perform well enough from my rifle to allow for affordable practice at extended range. I could then use the CE's to polish my skills that last little bit and would load them when I carry my rifle afield for more serious purposes. UPDATE: After running the tested velocities from my rifle with the 350 SMK through JBM, I am intrigued. At sea level, with a muzzle velocity of 2450 fps, it stays above the transonic range past 1100 yards and stays supersonic past 1500 yards. If someone made a bullet like this that would actually expand, it could be useful as a hunting round. As is, I may actually use this bullet as a practice round. I will have to work with it some and see if I can get it to shoot accurately in my rifle. [/QUOTE]
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375 Caliber A-max...might be a possibility. Please read.
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