Bulges on 9mm case?

ohihunter2014 said:

RMR 124 gr RN ... 1 out of 10 bullets there is a slight bulge on the round ... I did notice that if I hold the bullet until my fingers meet the die and there is no bulge.

Any ideas on this one?

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Bullet could be tilting before being seated. The fact that holding bullet straight until it is guided into the die confirms the suspicion more.

I would inspect the bullet seating stem to make sure it is clean without any build up.

FYI, Lee seating stem pushes not on tip but further down on the nose/ogive (Note the hole in the center of stem).




I was tilting 115 gr Winchester FMJ bullets that has sharp bullet base which produced pronounced bulge on one side of case from insufficient flaring of case mouth but careful seating of bullet with sufficient flaring resolved that issue with slightly even bulge around the case neck which is normal.

Tilted bullets showing one-sided bulge



Straight seated bullets showing even bulge all around the case neck

bds, thank you for the post. Good illustration with the pictures.

Dave

ohihunter2014 said:

My bulge is not visible and only felt by hand.

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I exaggerated the bullet tilt for the picture.

To me, even bulge around case neck is a good thing showing sufficient resizing of case neck and good neck tension from seated bullet base.

But you posted you can prevent the one-sided bulge by guiding the bullets into the die? If that's the case, sounds like tilted bullet to me.


If the bulge is only on one side (whether visible or felt), it could be from tilted bullet and/or uneven case wall thickness - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-2#post-10711411

"As to measuring case wall thickness at case mouth:

• And this was the biggest realization - Depending on headstamp, case wall thickness varied at different points around the case mouth and multiple measurements were needed.

• Yes, case wall thickness is not often consistent. Some headstamp vary with less than .001" but some others vary with over .002" and this explains why some loaded rounds have out-of-round case neck.

• I initially took 4 measurements around each case mouth at 12/3/6/9 O'clock and found case wall thickness on the same case could vary up to .001"-.002" which significantly affected case wall thickness measurements since typical case wall thickness measured .010"-.012" on average (.002" range)."

And case wall thickness measurements .200" below case mouth where case wall increases in thickness and bullet base applies greater neck tension (bulge) on case neck - https://www.thehighroad.org/index.p...nd-bullet-setback.830072/page-3#post-10713822

I think I know the bulge scenario you describe, as I've seen it happen too. I think I'm barely flaring enough. So I have to put extra effort into ensuring the bullet is on the case pretty straight.

Your comment about holding the bullet until it goes into the die is interesting. I would say 9mm (and .38 Spcl) are the only calibers I *don't* do that with. For those calibers I set it on the case and let it ride on the ram up into the seating die.

The following is really anal retentive. But I stumbled onto it accidentally and once I noticed how much more confidence it gave me setting bullets I now do it with every round.

I am sure and hold the bullet so the base is in the middle-to-upper portion of my thumb and forefinger. That way, as I'm placing the bullet, the bottom portion of my thumb and forefinger feel the case mouth. I've found I'm much more accurate and consistent placing the bullet using this technique. Getting the detailed feedback on where the case mouth is seems to really help ensure it's on and straight.

I had a lot like that since I tend to do minimal flare. Doesn't hurt anything - at least as far as I can tell it just looks off, but function is fine.

If the FCD is fixing a bulge similar to BDS pics - even less extreme - sounds like way too much FCD

Yep, the bulge all the way around is pretty much normal, called the coke bottle effect, If you don't get it at least a little bit chances are your 9 mm is not fully resized. Remember the 9 is a tapered case, not straight wall.

I would look at the press first if the die is not inline with the ram, fix that first. Check the shell holder make sure it is flat and not tilting the case.
With my RCBS dies I've noticed when the components of the die are tightened they are not inline with the die body, this maybe do to the excess tolerance of the coarse threads of the die. Millwrights and machinists are aware of this so I was surprised these dies do not have finer and tighter threads. So I tried teflon plumbers tape to take up the slop and this improved concentricity considerably. I use gauges to insure proper alignment of the die components when things are tighten up.
Starting the bullet straight is the most important step, sometimes spinning the case while starting the bullet can help.
I do not load mixed head stamps there is too much variation and it creates more headaches than it fixes.