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August 27, 2014, 06:10 PM | #1 |
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Hand loads for Competition
For my K-31, specifically. I have 150 grain JSP s using 46 grains of powder in a resized .284 winchester case. I got about 1 3/4" group off a wobbly picnic table at 70 yards with iron sights and got a 2" group with GP11, but im not sure if I want to use these, as they bruise up my shoulder pretty good. I plan to work a bit more on the loads though, but I was wondering. With my 150 grain JSP flat base bullets, would I get better performance with boat tail 150 grn FMJ's at 200 yards? Or would I need a heavier bullet like a 168 grain? Or would the flat base be just as well? Just wondering. Thanks again.
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August 27, 2014, 06:28 PM | #2 |
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Generally, boat-tail bullets are really only better beyond 300 yards. Specifically, no way to know what will work without trying it in your gun.
200 yards is not very far, in the sense of requiring much from the bullet. Whatever works at 100 (or 70) will work just as well at 200.
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August 27, 2014, 06:34 PM | #3 |
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Great, makes it a lot easier on my wallet that way. Haha. So I imagine there wouldn't be any performance difference between FMJ and JSP?
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August 27, 2014, 06:38 PM | #4 |
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FMJ (or match type hollow points) will generally slightly more accurate because the tips on SPs is easily damaged. As it turns out, the tip is less important to accuracy than you'd think but at the very least they don't look as pretty when they're dented.
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August 27, 2014, 07:03 PM | #5 |
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Okay. Well thank you for your help! I was just rather curious about the different types of bullets.
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August 27, 2014, 07:35 PM | #6 |
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Note that in the late 1950's, hollow point boattail 30 caliber match bullets were found to be more accurate than FMJBT boattail ones. Their heel at the start of the boattail was more uniformly shaped. Gas escaped around them more uniformly and bullets tipped less when leaving the muzzle.
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August 27, 2014, 11:01 PM | #7 |
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I think this might be a little on topic and off topic at the same time so feel free to shoot this line of questioning down . Why are most match bullets hollow points . That must make the tip lighter ??? If so that seems to just put more of the center of mass behind the center of pressure therefore needing more spin to stabilize . Why isn't the Match bullet as heavy as possible at the tip and hollow/lightest at the back . Creating more weight closer to the center of pressure making it easier to stabilize ???
That's right I'm trying to re-invent the wheel with just enough knowledge to be dangerous
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August 28, 2014, 08:08 AM | #8 |
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Match bullets are hollow points because the jacket making operations end up with the bullet's heel more uniform in dimensions as measured to the sub ten-thousandths range; they're more perfectly round. The coin, cup, draw and trim operations make a basic jacket. Then a precision lead core's pushed in then the cored jacket goes into a pointing die that closes the ogive over the lead core. With that lead core some distance short of the tip, it shapes more uniformly than if it was closer to or at the tip. Non-uniform core shapes mean unbalanced bullets. The more the front part of that core is squeezed down, the more it may do so unevenly. At a spin rate of 150,000 to 200,000 rpm's, it doesn't take much unbalance to make centrifugal forces enough to pull the bullet off the bore axis at it exits.
With very uniform bullet heels, gas escapes very uniformly around them as they exit the muzzle. Otherwise, uneven gas escape tips them a tiny bit and they don't shoot as accurate as they have to recover from that initial unbalance. They change direction doing that. Benchresters learned 22 caliber hollow point bullets were more accurate for that reason back in the early 1950's. Sierra Bullets tried that with their first 30 caliber hollow point match bullet, the 168-gr. International developed in the late 1950's. It's better accuracy over their 180 and 200 grain FMJBT match bullets convinced them to make them hollow pointed and add a 190-gr. one to go along with the crowd. Scores jumped up as a result. Western Cartridge Company's circa 1950's 180 and 200-gr. 30 caliber match bullets were also FMJBT ones through 1958. Some lots of them gave Sierra a run for the money accuracy wise, especially in oversize groove diameter Winchester factory match barrels as they were larger in diameter than Sierras. They made the ones used in WCC60 .308 Win. match ammo 197-gr. hollow points but the same .3087" diameter and they shot more accurate than the 200-gr. FMJBT ones. Pointed bullets have less drag than blunt nosed ones that are weight heavy at their front end. Their gyroscopic stablizing properties keeps them spinning such that their axis is parallel to the trajectory path. Passed footballs are equal weight and shape from their centers to both ends. When spun at the right speed, their spin axis also remains parallel to their trajectory; watch 'em do that in the next game you see on TV in close-ups of them in flight. They nose over so nicely at their maximum ordinate just like rifle bullets that are heavy and blunt at their back end, but light weight and sharp at their front end. Load some spitzer flat based bullets backwards and see how they shoot for accuracy. They'll be as front heavy as can be and have a very low drag back end. Last edited by Bart B.; August 28, 2014 at 11:06 AM. |
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