9MM bullet depth seating problem...


August 2, 2010, 10:07 PM
I sent for some MBC smallball and thought I'd try them out. After all, the price is right. I'm using a Lee Turrent press, although I'm using it in the stationary mode and the turret is not turning. I'm also using a Lee die set.
The problem is that I can't get a consistent bullet depth. I actually did get one to seat at 1.15" COAL. I've tried for hours over several sessions using several dummy rounds. :banghead: I even took the die apart and cleaned it. No matter how high I adjust the seater plug, the bullets get seated deeper! So I use a hammer type bullet puller and take it apart and try again. I also reset the entire die depth per Lee instruction sheet. I've never seen anything like it. I also have a Lyman Turret press and thought maybe I'd place the die in that.
I'm really stuck on this one. I could use some ideas.

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August 2, 2010, 11:39 PM
The bullet must be hitting something in the seating die and not the seater plug.
Unscrew the seating die a couple of turns and try seating a bullet in a dummy round.
Use a fired case for the dummy rounds instead of a sized case and pulling the bullet will be much easier.
Note the OAL, screw the seater plug in a turn, run that dummy again, and if the OAL is shorter, the seater plug is now controlling the OAL.
Lock the seater die there and adjust the seater plug to get the OAL you want.

My experience with MB smallball is a OAL of 1.080-1.100 works best. YMMV

August 3, 2010, 07:46 AM
Bullet Seating Adjustment

The trick is to set the bullet seating depth first, then the crimp. This is done as follows; With an empty, sized case in the shell holder, hold the ram at the top of its stroke. Turn the bullet seating die body down over the case until you feel it come to a stop. This will be when the case mouth contacts the crimp shoulder inside the die. Mark this position by turning the lock ring down against the turret or press frame. Now adjust your bullet seating depth. Once you have the bullet seated to the desired depth, back the bullet seater adjuster out about 1 turn. Now turn the bullet seating die body in to apply the desired crimp. Once this is established, hold the ram at the top of its stroke and spin the bullet seater adjuster down until it stops.

It is a good idea to carry this out with an empty case, so that after you have seated the bullet, you have a perfectly safe "dummy" cartridge (or gauge) to repetitively set seating depth and crimp on future occasions.

Once you have this "dummy" gauge, all you have to do is place it in the shell holder, raise the ram to the top of its stroke, turn the bullet seating body down until it stops, and then turn the bullet seating depth adjuster in until it stops. Since the crimp and the seating depth were already set, the die will return to very close to the same settings.
Seating depth variations

There are a number of possible causes for overall length variation. One is the way it is measured. If you measure overall length from the tip of the bullet to the base of the case, remember to subtract the variation due to bullet length tolerance. The bullets will vary in length due to manufacturing tolerances (bullets with exposed lead noses are the worst in this regard) and this will add to the overall cartridge length variation. Remember that the bullet seater plug does not (or shouldn't) contact the tip of the bullet when seating, but contacts farther down the ogive. For a more accurate seating depth measurement, take the seater plug out of the bullet seating die, place it on top of the cartridge and measure from the base of the case to the top of the seater plug.

Another possible cause for bullet seating depth variation is seating and crimping at the same time when trying to apply a firm crimp to untrimmed cases. Variation in case length also causes variation in the amount of crimp applied. Long cases get a heavier crimp than short ones. When seating and crimping at the same time, the crimp is formed as the bullet is seated into the case. The crimp will form sooner on a long case, and therefore the bullet will not be seated as deeply. The solution is to seat and crimp in a separate step (the Lee Factory Crimp die is good for this) and/or trim cases to a uniform length.

The amount of force required to cycle a progressive press varies with the number of cases in the shell plate. When the shell plate is full, it is harder to lower the lever than when there are one or two cases present. This can lead to variation in cartridge overall length because there are different loads placed on the working parts of the press. When the shell plate is full, seating depth will be slightly long, because the load is higher and all of the clearances are taken up. With the shell plate nearly empty, the load is not great enough to squeeze out these clearances, and the seating depth is short.

August 3, 2010, 02:42 PM
OOPs, I gave up seating AND CRIMPING at the same time long ago, because of this type of problem, and just assumed the OP was seating, THEN crimping....my bad.

Seating, then crimping...the reason most progressives have 5 stations!!

August 3, 2010, 08:51 PM
Thanks, I'll give that a try. I have a taper crimp die for crimping, so I can set the other die rather high if I have to.

August 4, 2010, 08:29 AM
Taper crimping auto calibers in the same step as seating is simple because there is so little crimp going on. No need to seat and crimp 9MM in separate steps unless one just wants to.

Red Cent
August 4, 2010, 01:13 PM
Is there a bullet stuck in the die?

August 4, 2010, 06:47 PM
I don't mean to be pedestrian, but are you fully stroking the lever every time? Is the lock ring snug against the press so that the die can't wiggle up & down?

I sympathize, but can't say I've had a problem keeping an approximate OAL every time. By approximate, I might vary a couple hundredths but not much more. I have to squeeze my 9mm Smallballs down to 1.07" or shorter OAL to run in my CZ. I am set for OAL of 1.068 per my caliper. I might vary a little over a run of 100 rounds, but never by much.


August 4, 2010, 11:50 PM
Mr Bone -
Several thoughts...

• One issue might be you are expecting the die to seat the bullet within .001" which simply can't be obtained or held. You should be happy with a range of OALs falling within + or - .007" of the listed length. That will give you a range of about .015" in total variation. As you learn your machine this will decrease.

• I also agree you might be crimping before the seating is finished. Unscrew the body of the seating die about 1/4 to 1/2 turn. Once you get your OAL going (inner anvil adjustment), then slowly work the body (the outer adjustment) of the die up or down to correct the crimp. I like to see about .378" on just the last 1/32 of the case mouth.

• Is the bullet seating anvil up inside the die round or flat? Pushing on RN bullets with a flat anvil will give you issues sometimes.

August 9, 2010, 09:19 PM
The crimping part of the die was too low. So I raised the die up several turns and then adjusted bullet depth. It works fine now. Thanks.

August 10, 2010, 01:06 AM
Thanks for posting back and glad we could help.

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