.40 S&W Reloading Question

[5hundo]

Is there any significant problems in using .400 diameter bullets for .40 S&W vs. using .405 that is technically the specification?

Do those 5 thousandths make a huge difference?

Is it even safe?

[762cavalier]

Spec for .40 caliber bullets is .400 not .405 so there should be no problem.

[5hundo]

Spec for .40 caliber bullets is .400 not .405 so there should be no problem.

Hmmm...

The Lyman manual says the spec for .40 S&W is .405...

It says the 10mm spec is .400. It's the crappy 49th edition, though...

So, I'm good?

[762cavalier]

.40 is just a shortened 10mm both use the same bullets. Lyman manual must be a misprint

[5hundo]

Lyman manual must be a misprint

Wouldn't be surprised. There has been some bad feedback about the 49th edition...

Thanks for your help, man!!!

[sargenv]

I suspect that .405 is a typo and they possibly meant to say .4005. Just like .355 bullets tend to be .3555" when measured to the 4th digit.

[5hundo]

If the spec for .40 S&W was on the smaller side, and the .405 was th larger spec, I would be more concerned.

Going a little bit looser on the spec is A LOT less dangerous that going a bit tighter...

[fairfaxjim]

As said above, the bullets for the two are exactly the same. The only physical differences are in the cases, and of course load data.

[5hundo]

Thanks for the info, guys!!!

I've played around with some loads to see what I like. I bought a box of 155gr. Hornady HP and I loaded up some with Unique and some with 231.

We'll see how I did...

[supersonic]

The correct diameter will be .40" / 10mm. Simple as that.