The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Small Calibers .243 point of impact variations.Go | New | Find | Notify | Tools | Reply | |
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| One of Us |
i thought id test where some of my other bullets hit after i had my 75grain hornady hollowpoints sighted in. all were shot from the same gun with the same scope. all are seated the same and shot exactly the same. point of impact listed is the average of 3 groups. all are hornady bullets with varget powder in winchester cases with federal primers. 75 gr hollow points are dead on at 100 yards 95 grain sst's hit a half inch higher 87 grain bthp's hit 3 inches high and 1.25 to the right 100 grain spbt's hit 3 inches low 87 grain v max's hit 2 inches high and an inch to the right 68 grain vmax hit 1.5 inches to the left. all but 3 groups were sub moa. the point of impact for each type of bullet was within a 1/8th inch for each group if at first you dont succeed. blow it up. | ||
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| One of Us |
Interesting comparison. I've noticed the bearing surface has a bit to do with it - along with bullet weight of course. My 243 (and older Win Mod 70) likes one factory load over another by a wide margin. . | |||
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This is really enlightening. I have never done this, but need to with my .243 since I shoot several different projectiles in it. I'm a little surprised at the lack of, what I'd call predictability, about where the other bullets would hit. For example: I would have expected the 95 grain bullets to hit lower than the 75 grain bullets. Then, with only a 5 grain difference, the 100 grain bullets shot so much lower than the 95 grain bullets? I'm not sure I understand what is going on. Does a difference in ballistic coefficients make that much difference? I'm really curious to hear what others have experienced doing the same type of experiment. Red C. Everything I say is fully substantiated by my own opinion. | |||
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One of Us |
I've used my .243 for varmint work since I bought it a while ago and have been pleased with the performance of the 55grain NBT's on Varmints and a couple of mule deer. My hunting buddy seemed to always have a .243 for a walk around varmint rifle of some make or another. I watched him shooting running coyotes at 150 yards with it and became very impressed with it's performance as we hunted together. He shot 70 grain NBT's all the time and this was his only load. That's why he was so successful; one rifle - - one load!!!!!! I started messing around with some 70 grain NBT's and found a load with 760 powder that is what I'm looking for. I was looking for a round for some longer range work on coyotes in these open areas here in the West when we are contending with stronger winds. The velocity was 3750 fps through my chronograph and the accuracy was just about the same....1" +-at 100 yards. The thing I was concerned about was the point of impact between these two weights and how I would compensate for them. At the range it turned out that the point of impact was the same at 100 yards. I had expected some different result but was well pleased with the result. I now will do some more testing for the downrange results and see what differences pop up there. | |||
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All barrels vibrate and whip when being shot and differnt bullets even of the same weight can change the harmonics of this and put bullets to a differnt spot. That and small or large changes in velocity, pressure, and bearing surface of a bullet come into play too. BC of the bullet changes it to but i would think youd have to get out past a 100 yards to make that actually change anything much. In some guns the change is greater then others. I have an 06 i was working up loads for this summer using 4 differnt 150 plain based spitzers using the exact same powder primer and case and There was as much as 5 inches difference in point of impact. Then you take my 300 win mag. It is exceptional in that just about all my loads using 150s 165s and even 180s will shoot so close to poa that they overlap. [/QUOTE][/QUOTE] | |||
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| One of Us |
You really just have to shoot and see what is going to happen. I wouldn't have bet on it, but I came up with a 90grn Sierra hpbt load with H380 that impacts at most 1/2 higher than my standard 117grn Hornady load with RL19 for my 257Roberts. How that happened, I'm just leaving to luck. But it is nice to be able to grab a lighter varmint type bullet or a heavy for calliber bullet and go hunting without having to rezero. | |||
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| One of Us |
each load is generating differences in pressure and velocity... faster velocity & pressure with a right hand twist it will be high and too the right... lower velocity and pressure, down and to the left... all are adjustable with a scope if you know how to read and utilize the adjustments... it surprises me on how many people don't... | |||
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| One of Us |
Lloyd has it licked, all barrels resonate in elliptical motions that vary depending upon barrel & bullet length, weight, contour, speed, twist, acceleration, temperature, etc... Captain Finlander | |||
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I read last year on another board about a guy who was using 55gr NBTs and 105 Amax's without scope adjustment. The Amax's were for his long range shooting in wind conditions. He has a Savage VLP and that is what I have, so I got both bullets and tried the same loads he used. The 55's shot high (no surprise) and grouped 2" left. The 105's shot low (again, no surprise) and grouped about 2" right. The rifle had been sighted in prior to that test with 70gr MK's. | |||
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| One of Us |
I just finshed checking a 260 Rem zeroed 1.25" high at 100 yrds with 100 grain Partitions shoots 300 below that with 100 grain B-tips. | |||
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| One of Us |
i have a chart taped to the stock of the rifle with all of my 100 yd zero scope settings written on it. 75 grain is my gf's target load, 87gr bthp and v max are my target and coyote loads. whichever i may choose. the 95 grain and 100 grain are my deer/bear loads and the 68 grains i shot because i got them for free. i was just testing to see how badly it would change. in my 30-06 i can use 150 grain psp bullets from 2 different manufacturers and they will hit 3 inches apart at 100 yards. the 100gr spbt actually had the highest bc too. if at first you dont succeed. blow it up. | |||
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Barrel time vs recoil makes the big difference in POA. Even the same bullet shot at the same velocity, but with podwers of different burn rate can greatly effect bullet impact. The slower powder will huit higher than the faster powder. The longer barrel time of the slower powder means the bullet will leave the barrel after it has risen farther from recoil. Thus a higher impact point. The only way to know if you can do a thing is to do it. | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Small Calibers .243 point of impact variations.
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