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9mm case bulge


TimG_SC

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I am new to reloading and I have anotther question for you guys. In alot of my loaded rounds I am getting a slight bulge in the middle of the case that appears to be where the bottom of the bullet sits. I am using 147g Montana Gold's loaded with 3.2gr of tite group. I set station 1 with the die right at the shellplate at full stroke, with case measured in the middle @ .375 and the bottom of the case near the grove is around .383. Station is charging consistantly while flaring to the low .390's. Station 4 is seating to 1.125 and station5 crimp is around .393. Is this slight bulge normal and if not what do you think is causing it? I shot a small batch (30 rounds) and the all fed and ejected fine in my XDM 5.25 and chronod. At an average of 883 fps.

Thanks in advance for your help...you guys have been awesome so far answering my questions.

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Look up "coke bottle" in the reloading forum.... If that is what you are talking about, its normal with a Dillon.

What he said. I'll add, you want a little coke bottle effect. It is telling you the bullet is stretching the case which means it is nice and tight and you won't have to worry about set back.

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Not sure if the OP is talking coke bottle.

The 147's are long, and at shorter OAL's may bulge the internal taper of the brass.

I don't load anything like this, so can't help much, but that's what I would be looking at.

Expect different lots of brass to bulge differently. Some may not chamber. Upside is you will not experience setback.

If the load is otherwise safe, and functions 100% no reason you can't keep doing it.

Edited by wide45
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Lots of 9mm appears bulged, sometimes in different places (mixed range brass). Nearly all my rounds that don't pass the case gauge (Dillon) will pass a chamber check (FNP9). The few that fail the chamber check I recheck after pulling the bullet. My brass, usually, is fine, the bullet is a little "fat" (Precision Moly 9/125 FP).

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TimG_SC, do you mean like this?

img0664t.th.jpg

It's pretty common for us boolit guys to get this look as we use larger diameter projectiles (1 or 2 thou over groove diameter).

It is indeed possible, though, to get this affect simply due to seating too deeply, particularly with working with heavy for calibre bullets. The 9mm case starts to taper internally after a certain point, and the designers never had 147gr projectiles in mind. Here's some elaboration I binged for you: http://www.xdtalk.com/forums/ammo-can/157652-inside-9mm-case.html

Edited by Dannix
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+1 Coke Bottle being completely normal.

I had a similar issue,I was experiencing a large amount of bulge. I found that my sizing/depriming die was not threaded all the way down and was allowing the brass to expand where it was unsupported by the die's walls. I reset my toolhead a few times before I figured out the problem. I also found that if I ran my powder die a little lower than suggested, and opened the mouth of the brass, it helped with getting the bullet properly seated, generating a better piece of ammo.

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