.40SW Brass Mileage

[natomasboy]

Hi all -

I have 2 general brass reloading questions:

1) What kind of mileage do you get on your .40sw brass?

I load very light: 180gr cast lead using 4.2gr Bullseye and/or 5.2gr WSF (only powders available).

I've been re-using my brass and on my 5th re-use. I don't see any signs of wear and pockets still keep primers snug. The batch of brass is a mix of Winchester, Federal, PMC, RP, and Speer (almost all Speer are nickel-plated).

I've looked for pitting, cracks, nada.. I do tumble and polish to see any obvious brass abnormalities.


2) What is your process of shooting through your brass?

I have about 5k of .40SW brass and I've polished, decapped, and sized them all. However I just re-use 150 rounds (how much I take to the range) of the same over and over.. As mentioned I'm on my 5th iteration and still no signs of wear.

Thanks!

[buffybuster]

If you're running a light load and your chamber is fully supporting the case, the brass will last a LONG time (~20+ reloads). I usually loose them before I wear them out, but if they do wear out, the case/neck will crack. Early Glock .40SW had notoriously loose chambers with poor support. As a result those cases didn't last long.

[natomasboy]

Buffy,

How do I know if my "chamber fully supports the case"?

[Bug Splat]

Barrel on the right is not fully supported. Barrel on the left for the most part is supported. What you are looking for is to see if the case wall is covered by the chamber. Cases that fired through unsupported chambers tend to grown or expaned a bit more. When you resize the case you are pushing the case back into shape. The more you expand and resize the metal the weaker it gets and the less life it has. Firing a weak case in an unsupported chamber could and has caused KABOOM's. The gas get pushed out through the case wall and not the barrel.



Unsupported kaboom


What a weak case looks like after firing

[natomasboy]

Thank you for the very clear explanation! Here's a shot of my barrel with one in the chamber. I'm thinking well supported since I can only see the rim of the case.

[Bedlam]

Technically any pistol of the browning design does not provide full case support but they are specifically refering to glocks here hich provide less support because their feed ramp cuts into the chamber more providing more reliability in rough conditions but less support to the case

[natomasboy]

If your gun has full case support, that doesn't necessarily make it impervious to the kaboom right? Where would the excess pressure go?

[Bedlam]

It can split the chamber in extreme cases it may also blow your magazine right out basically it can blow the back of the case off I belive not 100% on that but I have seen some pretty messed up guns from kabooms that are solid pistols with full chamber support.

[natomasboy]

Not that I want to push the envelope but are the pressure limits for my gun listed anywhere? (Sig p229)

[buffybuster]

Not that I want to push the envelope but are the pressure limits for my gun listed anywhere? (Sig p229)

If the case is fully supported, the weakest part of the case becomes the caseneck/casehead/primer pocket. It takes over 50Kpsi for those to deform.