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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Ladder test and scientific method question for the ballisticians.
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<blockquote data-quote="4ked Horn" data-source="post: 146641" data-attributes="member: 11"><p>Hey guys 4key's back. I've been in a bit of a hovering pattern recently with the long range stuff but I am hitting the reloading hard and heavy with some new wildcat bullets that recently found their way into my mailbox.</p><p></p><p>Heres the background: Richard sent me some 169.5 gr rbbt .30 cal open meplat j4 jacketed bullets. I put them on top of my standard loads of 41.4 gr of h335 in once fired brass and the groups were phenominal. 1 to 1.5 inch range at 300 yards.</p><p></p><p>Heres the procedure: I ordered 100 169.5 gr rbbt tapered jacket .30 cal bullets. They were the same uld shape but did not have the open meplat. I loaded them the the same distance from the lands and did a ladder test at 300 yards with a .3 grain increment using varget.</p><p></p><p>The ladder test showed a clear and consistent "peak and valley" pattern. at the bottom of the valleys there were 3 shots then the string would peak again within 1 shot. the velocities would also climb consistantly.</p><p></p><p>I chose to load six 3 shot test loads around the 2 loads in the highest velocity valley with each 3 shot group loaded in .1 grain increments. Basically trying to tune in on the highest velocity accuracy node.</p><p></p><p>Heres the results: The 300 yard groups were unsatisfactory. There were groups that strung out sideways. There were groups that strung verticaly. The smallest group was a symmetric triangle that was 3.5 wide by 1.5 inch high. Nothing consistant from one group to the other where I could say "these 3 groups are OK but this is where they start falling appart."</p><p></p><p>As a control to this I also loaded three 3 shot groups with the h335 powder that had worked so well with the test bullets. I loaded 41.3 41.4 and 41.5 gr to see if I had the same good results I had before. These loads were the worst of all. I couldn't believe what I saw.</p><p></p><p>The question: What do I do next? The variables changed were a change in powder (except in the control test), a change in jacket design and a change in new brass from once fired and neck sized.</p><p>I don't know if I should try the same 3 shot groups from once fired brass? Should I scrap my hopes of using varget? Should I throw away the data from the ladder test and use a conventional 4 or 5 shot group test with loadings in .2 gr increments starting 10% below max load?</p></blockquote><p></p>
[QUOTE="4ked Horn, post: 146641, member: 11"] Hey guys 4key's back. I've been in a bit of a hovering pattern recently with the long range stuff but I am hitting the reloading hard and heavy with some new wildcat bullets that recently found their way into my mailbox. Heres the background: Richard sent me some 169.5 gr rbbt .30 cal open meplat j4 jacketed bullets. I put them on top of my standard loads of 41.4 gr of h335 in once fired brass and the groups were phenominal. 1 to 1.5 inch range at 300 yards. Heres the procedure: I ordered 100 169.5 gr rbbt tapered jacket .30 cal bullets. They were the same uld shape but did not have the open meplat. I loaded them the the same distance from the lands and did a ladder test at 300 yards with a .3 grain increment using varget. The ladder test showed a clear and consistent "peak and valley" pattern. at the bottom of the valleys there were 3 shots then the string would peak again within 1 shot. the velocities would also climb consistantly. I chose to load six 3 shot test loads around the 2 loads in the highest velocity valley with each 3 shot group loaded in .1 grain increments. Basically trying to tune in on the highest velocity accuracy node. Heres the results: The 300 yard groups were unsatisfactory. There were groups that strung out sideways. There were groups that strung verticaly. The smallest group was a symmetric triangle that was 3.5 wide by 1.5 inch high. Nothing consistant from one group to the other where I could say "these 3 groups are OK but this is where they start falling appart." As a control to this I also loaded three 3 shot groups with the h335 powder that had worked so well with the test bullets. I loaded 41.3 41.4 and 41.5 gr to see if I had the same good results I had before. These loads were the worst of all. I couldn't believe what I saw. The question: What do I do next? The variables changed were a change in powder (except in the control test), a change in jacket design and a change in new brass from once fired and neck sized. I don't know if I should try the same 3 shot groups from once fired brass? Should I scrap my hopes of using varget? Should I throw away the data from the ladder test and use a conventional 4 or 5 shot group test with loadings in .2 gr increments starting 10% below max load? [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Ladder test and scientific method question for the ballisticians.
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