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Rifles, Reloading, Optics, Equipment
Reloading
Finding Jam - I thought I knew how
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<blockquote data-quote="Les in Wyoming" data-source="post: 2072404" data-attributes="member: 115820"><p>OK, this stuff is driving me crazy. I had a fairly good load with Hornady ELD-M. But I was running out of bullets, so I figured I needed to try others. In so doing, I have learned more and changed how I am finding jam for seating depth. When I did my Hornady 208 ELD-M load, I pushed a bullet into the lands with a small dowel and ran the cleaning rod up to it. I bought a simple cartridge length kit where you put a clamp on it where it meets the bolt face and then another where it meets the bullet at the lands. The measurement you get is supposed to be your COAL at jam. I developed a load from that figure, starting at .014 jump and went up in .003 increments. As it turned out, my best groups were at .020 to .026. So I have been loading at .021. (Erik Cortiz method). </p><p></p><p>Well, as I was developing a new seating depth for these different bullets, I went back to using the method we have discussed here. I set a bullet long in a case and closed the bolt. 210 gr Noslers got 4.004. Interestingly enough, 210 Bergers got the exact same figure. So I decided to see how 208 gr Hornady's do. It got 4.000. Hmmmm. they are all about the same. But when doing others, I got anywhere from 4.0020 to 3.965. Each got the same reading when pulling the bullet and doing it again. In testing 10 different ones, 4 got between 3.965 and 3.975. So I "called it" at the shortest one. (And this is supposed to be exact?) So that is my new "jam." I am measuring at the ogive. </p><p></p><p>So now, I am using the Berger method and am going to test loads with .010 jump, then .050 jump and then .090 jump. According to them, a node is about a .040 wide band. So this method is to quickly find it, and then you tune it from there. </p><p></p><p>As I shoot these, with bullets ranging as much as .055 where the ogive hits the lands, how in the world can these increments make a difference? I have some labeled at .010 jump, .050 jump and .090 jump. But honestly, they all could vary far more than that. </p><p></p><p>I have read that when finding jam, you should use the same bullet and same cartridge. I guess so. This keeps you from being confused at how different they all are. So what I am wondering is, why even bother if they all hit the lands at such different measurements. Each bullet has marks where they meet the lands and each is a radical different place, though all the bullets measure within .001 or so.</p></blockquote><p></p>
[QUOTE="Les in Wyoming, post: 2072404, member: 115820"] OK, this stuff is driving me crazy. I had a fairly good load with Hornady ELD-M. But I was running out of bullets, so I figured I needed to try others. In so doing, I have learned more and changed how I am finding jam for seating depth. When I did my Hornady 208 ELD-M load, I pushed a bullet into the lands with a small dowel and ran the cleaning rod up to it. I bought a simple cartridge length kit where you put a clamp on it where it meets the bolt face and then another where it meets the bullet at the lands. The measurement you get is supposed to be your COAL at jam. I developed a load from that figure, starting at .014 jump and went up in .003 increments. As it turned out, my best groups were at .020 to .026. So I have been loading at .021. (Erik Cortiz method). Well, as I was developing a new seating depth for these different bullets, I went back to using the method we have discussed here. I set a bullet long in a case and closed the bolt. 210 gr Noslers got 4.004. Interestingly enough, 210 Bergers got the exact same figure. So I decided to see how 208 gr Hornady's do. It got 4.000. Hmmmm. they are all about the same. But when doing others, I got anywhere from 4.0020 to 3.965. Each got the same reading when pulling the bullet and doing it again. In testing 10 different ones, 4 got between 3.965 and 3.975. So I "called it" at the shortest one. (And this is supposed to be exact?) So that is my new "jam." I am measuring at the ogive. So now, I am using the Berger method and am going to test loads with .010 jump, then .050 jump and then .090 jump. According to them, a node is about a .040 wide band. So this method is to quickly find it, and then you tune it from there. As I shoot these, with bullets ranging as much as .055 where the ogive hits the lands, how in the world can these increments make a difference? I have some labeled at .010 jump, .050 jump and .090 jump. But honestly, they all could vary far more than that. I have read that when finding jam, you should use the same bullet and same cartridge. I guess so. This keeps you from being confused at how different they all are. So what I am wondering is, why even bother if they all hit the lands at such different measurements. Each bullet has marks where they meet the lands and each is a radical different place, though all the bullets measure within .001 or so. [/QUOTE]
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Finding Jam - I thought I knew how
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