Is it me, the press, or the brass? What is going wrong?

[Gio]

I've been reloading for several years now, have had this problem only with 9mm, and have struggled to figure out the cause. About 3-4 rounds out of every 100 loaded won't pass the plunk test in a case gage. I'm loading on a Dillon 550b with Dillon carbide dies. The problem area seems to be about 2/3-3/4 of the way up the case where the bullet is seated inside of it that measures about .382-383 inches. The other 97% of rounds that pass the plunk test measure .377-.378" in that same spot. I use a mix of range brass, but the vast majority of my brass is once fired from quality Speer ammo. This problem seems to occur on all different types of brass and not one specific kind. I am using 145gr bayou bullets, seated to an OAL of 1.130". I also load .40 and .45 and rarely have a single round not case gage with either. Any thoughts on what I can try to remedy this?

[Peally]

Unless they vary in FPS or fail to chamber I'd just shoot em.

The bullets all the same diameter? All seating at the same OAL?

[Clusterfrack]

I used to have that issue as well. Now I use a Lee FCD in the final station on my press.

[Gio]

Unless they vary in FPS or fail to chamber I'd just shoot em.

The bullets all the same diameter? All seating at the same OAL?

Most will seat in a glock barrel but stick and won't spin freely. I segregate these rounds and shoot them separately during a live fire session, usually for slow fire accuracy like a dot torture drill to avoid inducing a malfunction.

[busdriver]

It sounds like the bullets may be seating crooked. Is the bulge all the way around the case or just out one side?

[Gio]

It sounds like the bullets may be seating crooked. Is the bulge all the way around the case or just out one side?

All the way around. I'll try to get some pictures posted tonight. I can't visually tell they are out of spec until they go in the case gage.

[busdriver]

Hmm. What are you crimping to?

[Clusterfrack]

Unless you're buying expensive bullets, you're going to have some variation. That's what was causing the bulging for me. The FCD swages that out, if necessary.

[willie]

The 9mm case is tapered. Your heavier bullet is longer. Carbide dies have a narrow ring cemented into the die. This ring sizes the case to the same diameter from top to bottom. The case is thicker at the lower end. When the longer bullet is seated, it's bulging the case out on the section that you refer to. This bulge is the reason for plunk test failure. The Lee FCD will solve your problem, but it may swage down the lead bullet in the process. If so, your lead bullet loads will likely cause leading because the projectiles have been reduced to .355 diameter--jacketed bullet dimension. Lead bullets must be larger in diameter. Most have found that .357 and .358 lead bullets work much better in the 9mm because they are more accurate and do not cause barrel leading. Despite the common misperception, 9mm barrels don't mike at .355; .357 and .358 diameters are more common diameters across brands. Some will mike at .360.

I suggest setting aside the fat ones and keep on shooting the others. You can shoot the fat ones or experiment by running them through a Lee FCD to see if leading becomes an issue. .357 and larger bullets loaded in 9mm cases will produce a coke bottle effect. That's fine as long as they function through your pistol.

[BN]

Try loading your bullet a little longer. You should be able to load to 1.140 or 1.150. That will bring the base of the bullet up farther in the case so it won't bulge. That might not work if you are shooting a CZ.