Reloading 9mm Luger problem

[Unclenick]

74A95,

Thanks for the fat finger catch. I fixed it, but can't figure out how I entered the error in there in the first place. Need to remember to reread slowly.

The reason for the minimum case mouth diameter being as large as it is is so that a cartridge lying on the bottom of the chamber still has at least a thousand of overlap at the top of the throat. The concern is that, theoretically, anyway, a hard feed might be able to upset the side of the. case mouth that catches the edge of the headspacing shoulder, thus allowing the opposite edge of the case mouth to be driven slightly into the throat. The thickness of the chamber's headspacing shoulder is 0.011.5", and if you add that to the 0.3580", you get 0.3715". Add a thousandth and a half, and you have at least a little contact all around the clock.

The guns that would have a problem if that criterion wasn't met perfectly are probably mostly in the category of full auto weapons firing from an open bolt. Nonetheless, that is how the dimensions are chosen, AFAIK.

 

[2CT199]

Something I'm surprised nobody else has said so far - I was tumble lubing Lee 125gr for 9mm and they worked fine. I started powder coating and about 1 in 4 will not chamber. It added just enough to make a difference - some of the time. I had apparently been right at the upper limit.

Fortunately I also have a 9mm revolver where it does not matter and in the future I will seat the bullet deeper so that is not an issue. As most of them work anyway it will not need to be much.

Case is fine. OAL is fine, but the plunk test revealed the bullet itself is hitting the rifling - where it did not before. This in both the stock Glock barrel and the KKM Precision barrel I got just so I could fire cast lead from a Glock. Same results.

 

[mehavey]

First action in powder-coating:
- Learn how to powdercoat bullets.

Second action in powder-coating:
- Re-determine your OAL

 

[Unclenick]

2CT199,

Welcome to the forum. Please pop over to this page and introduce yourself.

When the bullet touches the throat of the rifling, you are headspacing on the bullet instead of on the case's mouth. This can actually cut your group sizes down substantially. I've had up to 40% reduction in the 45 Auto. The limitation is that a loaded round dropped into the chamber must not stick out past the back end of the barrel or the barrel extension. With coated and lead bullets, you don't hear much of a "plunk" sound dropping one of these rounds in, but it does force alignment of the bullet with the bore, which eliminates shaving of lead (or coating) during firing, so the bullets stay better balanced and, for uncoated lead, it reduces lead fouling. It is also a more repeatable alignment, especially if you are shooting mixed cases with different thicknesses at the case mouth.