ELD-M Issues out to a mile

[Mr.Knowit all]

I spent some time in Idaho with my 7 Practical and shot from 1180M to 1600M. At 1600M I had a significant jump in required elevation (1.5 mils) to make hits that didn't track with any of my other engagements. I was only off by .2 mils at 1520M and dead on up to that point. I'm running a 28" 1:8 Krieger, pushing the 180 ELD-Ms at 3190. As strange as the jump in required dope was, the hits were consistent at both 1520M and 1600M. Calculator was a 5700 w/ the latest version of AB. All environmental data was backed up by about 10 other Kestrels, GPS, LRFs and compasses. Any thoughts?

I had some issues like that with my ELDMs 208 gr. I have a 1-8.5 twist and 27 in Bart. at 3094 fps. Crazy fast but no signs of over pressure and shoots under 1/2 min. so Im just rolling with it. But I wonder if the rpms are too high? Hornady said I was good to 3300fps but that is with a 10 twist so 3100 fps with a 8.5 MAY be too much? I don't know..... Maybe I will have to back to Bergers?

 

[284winner]

I had some issues like that with my ELDMs 208 gr. I have a 1-8.5 twist and 27 in Bart. at 3094 fps. Crazy fast but no signs of over pressure and shoots under 1/2 min. so Im just rolling with it. But I wonder if the rpms are too high? Hornady said I was good to 3300fps but that is with a 10 twist so 3100 fps with a 8.5 MAY be too much? I don't know..... Maybe I will have to back to Bergers?

I think they base their "safe too" speeds on their recommended barrel twists. I believe an 8.5 will be just fine for the 208s at the speeds you will be at (260,000 rpms).I think many of the problems with the Hornady bullets coming apart has to do with faster barrels than needed for bullet weight. Especially when there running the bullets alot faster than needed for the particular twist of the barrel. Todays cartridges are faster than ever with the newest powders available and bullet/barrel twist options offered. I had Berger 6 mm VLD bullets in 105s come apart using a 7 twist barrel at 3500 fps. RPMs were 360,000. Nobody seemed to blame Berger bullets. Just seemed everyone mentioned the fast twist and velocity was too much in that combination. They were right. An 8 twist worked perfectly. When speeds were dropped to 3300, there were no issues with the 7 twist barrel either. The guys on that particular forum knew what was happening. It was fairly easy to see as well.