40 S&W SAAMI cartridge specifications

[Major Mike]

My speer reloading manual #11 doesn't have any specs for the 40 S&W and I just recently accuired one . I managed to find some data on Wikipedia that indicates the following specs.Case type...Rimless,straight bullet dia... .40in. Neck dia. .423 in. base dia. .424 in. Rim dia. .424 in. Rim thickness .055 in. Case length .850 in. Overall length 1.135 in. I measured the inside of my pistols barrel at the mouth where the cartridge is supposed to seat and it miked out @ .4245/.4246 depending on how I puckered my bung hole during the process. Then I measured some brand new Winchester Ammo and I found it to be under sized by what would seem to me as quite a lot for brand new factory loaded ammo.... Rim dia .416 Neck dia .4185 Base dia .4185 Rim thickness .046 Rim dia .414 ??????? Seems to be a tad out of spec if what I read is correct. Is the new ammo out of wack or is it the data ??? Could this lead to case failures in an unsupported chamber??? Inaccurate groups due to a sloppy case/chamber ??? What do you think? Mike

 

[Wendell]

Those numbers look fine to me. Shoots okay, doesn't it? Didn't blow up, did it?

I think I want my ammunition to feed and function - no matter what.

 

[Major Mike]

The gun shoots , no doubt about that but does seem to throw flyers that I have a hard time explaining. I do know that when I remove the barrel from the gun and insert a cartridge into the chamber it doesn't fit anyway nearly as well as my other guns will. It can actually be heard rattlin around in the chamber if you shake the barrel. Can't do that with my 45 or the 9mm, they are definately much ,much tighter in that respect.