Chambering issues in 9mm

[DiRTY DOG]

A Lee Factory Crimp Die will likely fix your problem, like a bandaid to covering up a blister. But you'd be better off not having the problem in the first place.

Best keep looking for the root of the problem, which is your 147gr bullets and brass not playing together.

9mm case thickness is tapered. 147gr bullets seat deeper than 115gr or 125gr in order to pass the plink test. But seating them deeper means you're jamming the base of the bullet into the thicker part of the case.


Use a different 147gr bullet, or use different brass. Or increase your coal so they don't seat so deep, you may need to have your barrel reamed longer for 147gr bullets.

 

[kenhwind]

I just thought about something. A friend gave me some 10mm brass and some of the cases would not resize sufficiently, so I bought a LEE undersize sizing die.

Lee Undersize Carbide 9mm Luger Small Base Sizing Die

Lee U Carbide Undersized Sizing Dies are great for reloaders looking for ultimate feeding reliability in their handgun. These dies undersize brass...

www.midwayusa.com

I cannot help but think that the issue might be the bullet being seated too deep and bulging the case.

 

[Kracken McGraw]

All of you have missed the real issue. See the cannelure on the brass? That is there to stop a bullet from going any father into the case. The case gets thicker at that point. Notice how it bulges? The brass is made for 115gr bullets. Also lots of the European brass is WAY thicker than USA made brass and it makes it even worse.

You need to segregate your brass and stop loading whatever you find on the range.

And if you can find a set of steel dies this hour shape will not be as noticeable. Carbide dies do not size a tapered case well at all. There is no taper in any carbide die. Just straight. Steel dies will have the correct taper but you will have to lube the brass to use them. That is a deal breaker for some but not me

Hornady dies might be worth a shot for the OP too. I like mine for 9mm, and I lube them.

 

[243winxb]

There is no taper in any carbide die

RCBS has the carbide taper in their sizing die.

You need to segregate your brass and stop loading whatever you find on the range.

Yes, The brand does make a difference. Thick vs thin.
Not all brass has the taper. Avoid the "stepped" brass.

 

[dellet]

Even if the problem is internal diameter of the case, the bullet should cause an even bulge around the case. If it’s off center, the problem is simply the bullet is not being started straight.

It could be as simple as a nick in the rim groove or a bent rim not allowing the case to center in the shell holder. Note the circled area of cartridge you posted. That would easily explain the random problem.

As for a Lee crimp die, that might press the bulge out, but it won’t straighten the bullet seated off center.

 

[ToddKS]

A Lee Factory Crimp Die will likely fix your problem, like a bandaid to covering up a blister. But you'd be better off not having the problem in the first place.

Best keep looking for the root of the problem, which is your 147gr bullets and brass not playing together.

9mm case thickness is tapered. 147gr bullets seat deeper than 115gr or 125gr in order to pass the plink test. But seating them deeper means you're jamming the base of the bullet into the thicker part of the case.


Use a different 147gr bullet, or use different brass. Or increase your coal so they don't seat so deep, you may need to have your barrel reamed longer for 147gr bullets.

This is the correct assessment. This is a brass issue, not a sizing issue. If you want to run the 147's you will need to sort your brass by headstamp.

Of the headstamps you list, FC is likely the best, RP and WIN should work with the 147s as well. AMERC should be scrapped. I also recommend scrapping WCC. I find more blown case heads on WCC/WMA than all other headstamps combined 10:1. YMMV.

 

[243winxb]

Diameter of finished round that doesn’t chamber .388

Outside diameters should not be larger then the SAAMI drawing.