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Posted: 5/27/2013 10:51:38 AM EDT
| I think this belongs here in the reloading section. I recently changed the scope mount on my AR, so I needed to re-zero. I decided to use some Federal 55 gr fmj Lake City stuff I had picked up cheap, and then once zero was achieved I'd shoot a few group of a load I've been working on (Winchester cases, 21.3 grains of H322 and a Sierra Gameking 65 grain bullet. I got a nice 100 yard zero and was surprised at the groups I was getting with the Lake City/ Fed stuff (1/2 groups!). I zero for 1.5 inches high at 100 yards. I was even more surprised to see the 65 grain game kings shooting a good 4 to 5 inches higher at 100 yards than the 55 grain bullets. No windage change was observed. So, I do know that with every load you cant expect the same zero, but I'm curious as to what would cause such as extreme change in zero. I'm not complaining or overly shocked, but would love to hear other's opinions/ insight in the matter. |
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Quoted:
I think this belongs here in the reloading section. I recently changed the scope mount on my AR, so I needed to re-zero. I decided to use some Federal 55 gr fmj Lake City stuff I had picked up cheap, and then once zero was achieved I'd shoot a few group of a load I've been working on (Winchester cases, 21.3 grains of H322 and a Sierra Gameking 65 grain bullet. I got a nice 100 yard zero and was surprised at the groups I was getting with the Lake City/ Fed stuff (1/2 groups!). I zero for 1.5 inches high at 100 yards. I was even more surprised to see the 65 grain game kings shooting a good 4 to 5 inches higher at 100 yards than the 55 grain bullets. No windage change was observed. So, I do know that with every load you cant expect the same zero, but I'm curious as to what would cause such as extreme change in zero. I'm not complaining or overly shocked, but would love to hear other's opinions/ insight in the matter. Plug all the differentials into a program like Point Blank from RCBS. Save the table to txt. If your trajectories don't match then there must be a different variable that isn't in the program. My guess would be the height of barrel at bullet exit is higher due to increased recoil would be the first thing to look at. |
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Some of my varmint rifles will only show an inch or so veriation due to the length and weight
of the heavy barrel. Depending on the use of the rifle,you could or should make a shooters log and a reloading log book and note the setting on your scope or iron sights for each load you decide to keep as your pet load for that bullet. Sometimes heavier loads will shoot lower,some will shoot higher ocationally will shoot too the right or left.Probably due to barrel harmonics and recoil. Later John |
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