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Post by lapriester on Mar 16, 2017 18:50:36 GMT -8
My first batch of formed 6.5X6.8 cases made from SSA and Federal 6.8 had decent neck tension using a .289 bushing in my Redding die. I shot those cases without problems and resized and prepped those cases with the .289 bushing and put them away. That was about 8 months ago. The other day I decided to build some test loads with a couple of different powders. Charged the cases and started seating the same 85gr and 100gr Sierra Varmintors as before. When I seated the bullets in the Fed cases they slipped right in with almost no neck tension. I was able to push the bullet further in easily on the edge of my bench. No good. I tested the SSA cases and they were tighter but still much looser than the initial reload after the first forming. So I dumped all the powder, pulled the loose bullets, yanked the deprimer pin, changed the bushing to .288 and resized a couple. They still seemed too loose for my taste. Then I went down to the .287 bushing and the neck tension seemed much better.
So, what happened here? That much case spring back because they sat around for 8 months? The Feds were much worse. Because they are harder than the SSA cases? .002 sure seems like a lot of spring back. Or did I just not use the right bushing. I noted that the recommended is .287 but the guy who sold me the barrel said he used a .289 without issues. So did I the first sizing but not anymore I guess.
So, bottom line I just purchased a .286 bushing just in case this becomes an issue in the future. |
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Post by GLSHOOTER on Mar 17, 2017 6:28:13 GMT -8
Yes the brass will attempt to return to its previous size. Dead soft necks that have been annealed will be less prone to do so as the stresses have been "relaxed" somewhat. The phenomena is something that varies from lotto lot of brass. I know I forget this on occasion if I have made up the brass earlier.
I have a table for sizing down on initial case forming and now routinely take it down another 0.001 as the spring back starts coming into play. Some recommend going an extra 0.001 on sizing for the desired neck tension being a rule of thumb of 0.001 spring back. A bit extra tension never hurts but less sure doesn't.
Greg
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Post by lapriester on Mar 17, 2017 10:31:37 GMT -8
LOL, the first couple took me by surprise. I actually thought I'd mixed in some 6.8 cases by accident. But, realized if that was the case they probably would have come close, or actually fell in the cases. What a PITA to dump all the powder after careful measurement in 100 case and resize them. I eventually just went thru and sized all 300 I had in the box. Lessons learned. Now what to do with those larger bushings? I remember when I initially formed them they were nice and snug. I wonder what would have happened If I'd not shot those up two weeks later. If the bullets would have loosened I might have had a mess. If you remember a few posts back I mentioned how dirty the rifle got using AA2200. I wonder if loosening neck tension may have had a factor in that? I loaded them about 2 weeks before I actually used them for varmints. Hmm.
Oh well, I never complain about needing more range time so it's back to the testing ground again. H335 in my test loads this time. I'll post the results when I get out there. Dang rain is coming back here in CA all this weekend and most of next week so...back to hibernation mode again. Or, reloading mode.  |
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Post by GLSHOOTER on Mar 17, 2017 11:30:48 GMT -8
The soot could be a factor of the less tension beyond a doubt. Like I said I am now going 0.001 tighter to deal with some of that...lol
Greg
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Post by lapriester on Mar 17, 2017 23:00:47 GMT -8
Tighter is always better....in many applications, LOL.  |
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