Problem with 9mm falling into case

[9teenEleven]

I'm running into a problem that I've never experienced before and have run out of solutions to diagnose or solve the problem.

When loading fmj precision delta 124gr 9mm bullets, about 1 in 10 rounds are not holding the bullet. A little pressure and the round falls into the case. On the rounds that are holding, no amount of pressure will get the bullet to move. However, some of the rounds just aren't holding. I've identified the problem as isolated to certain brands of brass, but I'm not convinced that the brass itself is the issue. I've never run into this problem when using zero bullets, but I just bought 2000 PD bullets because zero was out of stock.

I don't have any zero bullets left to check against, but the precision delta bullets are measuring .355 at the base, but .353 before the olgive where the round is being lightly crimped. Is this normal?

 

[PT1911]

have you run your sizer die through the brass? i would venture to guess the same outcome...

 

[Wil Terry]

ACTUALLY, this is a simple matter of tolerance stack with certain bullets in certain cases with the expander plug you are using. A good sign the expander plug is okay for a particular situation is in the loaded round you can see the the base of the bullet ever so slightly on the outside of the case, a slight bulge.
IMHO .353" bullets are too damned skinny and should be discarded. .355" is supposed to be standard but .356" works perfectly well as most foreign 9MM barrels are around .357" give or take the odd furlong [ NO, I AM NOT KIDDING YOU !! ] THE barrel on my BR'HP slugs at .3572", the PT92/99 is a tiny bit smaller, the Luger is right there as is the P38.
I have loaded and shot tens of thousands of 38/357M pistol bullets in 9MM PARABELLUM pistols.

 

[9teenEleven]

Will, is it normal for there to be a slight taper on the bullet?

 

[918v]

No, not normal. The shank should have a uniform diameter of .355" at the least.

 

[bubbacrabb]

I'd call PD, I use their bullets all the time with no issues. Im sure they'll help you out. Usually a sweet talking southern gal on the phone. I just recently bought 4k of the 115 grain fmj, and they were loading fine. Hope it works out for you bud.

 

[rfwobbly]

Measure the wall thickness on that brass. Since the brass is sized from the outside, the wall thickness has a times 2 effect on case neck tension.

 

[gamestalker]

I've run into this before, specifically with 9mm. A little bit of measuring identified the culprit. Years ago 9mm was notorious for neck tension issues, and thus most brass had a crimp canelure just below the base of the seated bullet to prevent bullets from inadvertantly going deper into the case. My Speer #10 reloading manual addresses this issue and portrays it as a common problem. Additionally important was a test Speer performed in wich they used a load that produced 28,000 cup and then deliberatly seated the bullet .030" deeper. The .030" deeper seated bullets went from a 28,000 cup to 62,000 cup. Case mouth thickness between brands and lots of brass showed considerable variations back then, much of which has been addressed and resolved. Expander balls to not exceed .354" was established to be the maximum in an effort to further prevent neck tension failure. Adding to the problem of resolving this issue is the fact that 9mm cases headspace on the mouth, this limits the amount of crimp that can be utilized. This leaves us reliant on bullet and case mouth thickness to achieve acceptable neck tension.
With this said it is of great importance to perform the bench test after loading which involves taking each finished round and pressing the bullet against the the table top. If the seating depth changes on any, you'll have possibly prevented a serious pressure spike. Though some what unconventioanl, an additional step I take involves using a slower burning powder, which provides a compressed powder charge. This helps to minimize the risk of seating depths getting deeper but does nothng to prevent the primary issue of loose neck tension. For some this method is unexceptable because it goes beyond the desired velocity and recoil they are comfortable shooting.

 

[Jim Watson]

I run into the occasional 9mm case that will swallow a jacketed bullet, ususally a W-W.
I either discard it or put it in a box to load with cast bullets.
The brass is just thin.

If you have a lot of such stuff you can measure the expander plug, it ought to be substantially smaller than the bullet.
An EGW "U" sizing die will bring brass down a little smaller to develop more tension.

 

[Sky King]

I have the same problem with R-P brass in .38 Special. I load Hornady 125gr JHP. Works with every other brand I load except R-P. The way I'm able to use R-P is to size with my .380 die. I had the same 9mm problem years ago using RCBS steel dies. Corrected the same way using .380 die to just resize the top 1/4", worked until I purchased Lee Carbide die after that no problems

 

[Got_Lead?]

Ditto on the barrel dimensions, my Beretta 92 slugs at .358, SIG 226-.3565, Hi-Power .357, and a Star B Super at .359 The only gun I have that has a tighter bore (in that calibre range) is a S&W Model 52 .38 Master which measures .355", and it's a .38 special, LOL.

Anyway, those boolits seem a little loose up top, although .355 is normal for 9mm boolits. They'll probably shoot OK, if you can get them to seat up in the cases, the 9mm is an outside taper case. You could make shure the sizing die is screwed all the way down, but that only goes so far with carbide dies, if you look at the carbide insert, it is tapered, but its length doesn't extend the entire case length, and you are probably already FL sizing anyway. Undersize sizing dies are an option, however, they may be hard to find in 9mm, and they work the brass pretty hard.

Gamestalker makes a good point about the expander ball at .355" max. I have found a lot of store bought machinery needs a bit of TLC to make it work to intended function.

Good luck.