Gman57 Posted April 27, 2017 Share Posted April 27, 2017 (edited) I have 2 cases of MG 124 JHP and finding that the finished OAL fluctuates .004 to .005 That said I'm looking for 1.140 set up and it will range 1.137 to 1.145. And should say I have more over than unders. I don't have this issue with FMJ bullets, only thing I can figure is the hollow point tip has some jagged edges and will make the difference when seating. Anyone experience this? G Edited April 27, 2017 by Gman57 Link to comment Share on other sites More sharing options...
al503 Posted April 27, 2017 Share Posted April 27, 2017 Are you measuring rounds that are made when all of the stations of the press are filled? Other things to check/do: Pick out single headstamp brass to measure Make sure that your primers are at least flush/below flush Try to feel the same amount of click/stop/thud, whatever you want to call it when you hit the bo.ttom of the stroke If you're loading a compressed load, that could be the culprit as well. Link to comment Share on other sites More sharing options...
Gman57 Posted April 27, 2017 Author Share Posted April 27, 2017 Know exactly what your talking about at the finish of the stroke. Primers no issue, I would think brass should not be the issue if it was ,002 or .004 difference in case length we are measuring OAL and the bullet would just seat more or less in the case????? Link to comment Share on other sites More sharing options...
al503 Posted April 27, 2017 Share Posted April 27, 2017 You can have different case wall thickness with different head stamps. That difference might affect how far the bullet gets pushed into the case by the seating die. That (or that in conjunction with other factors) could make the difference. Link to comment Share on other sites More sharing options...
Gman57 Posted April 27, 2017 Author Share Posted April 27, 2017 Do you shoot MG 124 JHP 9mm? Link to comment Share on other sites More sharing options...
anachronism Posted April 27, 2017 Share Posted April 27, 2017 It seems to be pretty common these days for bullets to vary slightly in length and/or ogive profile. I just ran into this with some Hornady bullets too. Bullet length varied over .010 in some instances. Since I was loading a high-pressure cartridge (357 SIG) the difference really bothered me. I was paying heavy attention to crimp location and nose length (yup, SIG) and the discrepancies really leaped out at me. Rechecking my load data I decided the differences were negligible and finished up quickly. The fact of the matter is that there's no way to guarantee that any two jacketed bullets are ever identical. I don't think any bullet maker makes every bullet from the exact same forming dies and punches. It's simply not possible. You also see this situation a lot with rifle bullets. Link to comment Share on other sites More sharing options...
al503 Posted April 27, 2017 Share Posted April 27, 2017 43 minutes ago, Gman57 said: Do you shoot MG 124 JHP 9mm? Yes. MG and Zero's are my go to's for open. Link to comment Share on other sites More sharing options...
Hi-Power Jack Posted April 27, 2017 Share Posted April 27, 2017 7 hours ago, Gman57 said: MG 124 JHP OAL fluctuates .004 to .005. I don't have this issue with FMJ bullets, Have you flipped the bullet seating stem over from round nose to flat bullets? You usually use the round nose stem for FMJ's, and flat nose for JHP's. Link to comment Share on other sites More sharing options...
Gman57 Posted April 27, 2017 Author Share Posted April 27, 2017 1 hour ago, Hi-Power Jack said: Have you flipped the bullet seating stem over from round nose to flat bullets? You usually use the round nose stem for FMJ's, and flat nose for JHP's. Jack Thought of that and tried both ways seem to work better on the round nose side. Initially I was set up with the flat point side. Using a Dillon die thought about trying another manufacture. It's a mystery, with my 40 caliber 180 gr Montana Gold I am within .002 all the time. G Link to comment Share on other sites More sharing options...
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