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Posted: 5/25/2012 10:29:06 PM EDT
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I realize that the seating die goes off of the ogive so OAL isnt that important. This post is about Nosler 77gr OTM's
But my 77gr load calls for around a 2.255" OAL. So I seated 4 and got them between 2.253"-2.256" which I thought was pretty good. I then seated 47 total. I noticed some seemed pretty short. So I measured all of them. About 30 are around 2.245", a couple are around 2.240", a few around 2.250" and about 15 are around 2.255". The shortest is 2.238" and the longest is 2.257". Now to me that seems excessive. So I went and measured a few projectiles. out of 10; 6 were around .880", one was .885" and 3 were .892" Now what is annoying me is I'm trying to get the absolute best accurracy I can. The casings are trimmed to 1.750" and I have done every extra step possible, only to find out these Nosler 77gr seems very odd. I will point out though I weighed one of the .880" and .892" projectiles and they were exactly the same. I find it really annoying right now because now i have no clue what OAL I want, or I will get! As I said in the beginning my test loads were 2.255" 2.257" one left 2.238" on right 
.892" on left, .880" on right 
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| The Nosler 77's I've loaded do show quite a bit of variance when you measure oal. It's due to the difference in the hollowpoint tip. Some have more or less copper jacket material at the tip. Some even have more jacket to one side of the tip than the other. Your ogives are probably very close, just the irregular tips are causing the variance. Even Sierra 77's do the same thing but not quite as much as Noslers in my experience. I seat the longest to the oal maximum I want and some do fall shorter. Most say that this tip variance causes no change in accuracy but some actually trim the hollowpoint tips to be exactly the same and say this improves accuracy at very long ranges. They make a tool to uniform hollowpoint tips called a meplat trimmer: Here's one article on it:http://www.6mmbr.com/MCRMeplat.html |
| Ogive is really all that matters in terms of practical accuracy, you seat off the ogive so you're fine. This is a common issue with most HPBTs, its variances in the meplat it bugs the hell out of me so I limit my use of them, if it really bothers you they do make meplat trimmers and shapers. I find Hornady's BTHPs to be more consistent than SMKs and Amaxs to be near perfect. But as I said in the real world for those of us not shooting BR it doesn't really matter aside from setting your seating die a little short of mag length. |
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