300Whisper trim to length 1.355 not 1.400!

[Gos]

About once a month, someone is trimming down brass for their 300 whisper to 1.4". It's a pretty common mistake since that is the length of the .221 fireball; but not the 300 whisper. The real trim to length for the 300 whisper is 1.355".
Don't feel too bad. Even the Hornady book got it wrong.
The new Sierra book got it right.

How about a sticky for the trim to length before someone gets hurt trying to chamber a case that is too long in a 300 whisper chamber?
Gos.

[Cornholio]

The funny thing is I had a brain fart and trimmed all my brass to 1.450", and loaded them up. They fed and functioned perfectly in my upper. Hell, I even loaded them another 3 times without trimming them again and they still worked perfectly. I must have a big ass chamber!

[Gos]

I've loaded for some guns that did accept the 1.4 with no problems, but I have seen others that did not. I'm just wanting to see this thing set to a standard length.
It would be interesting to see with a casting what your chamber length really is. What brand is your barrel?
Gos.

[Cornholio]

Originally Posted by Gos

It would be interesting to see with a casting what your chamber length really is. What brand is your barrel?
Gos.

I have no idea. The seller told me it was an Armalite SS barrel. I never heard that Armalite ever made any Whisper barrels, but that's what the guy told me.

[Quarterbore]

What we need is some technical Specs and FAQ....

Here is a related thread from the past:

http://www.quarterbore.net/forums/showthread.php?t=147

[crossfire]

ammoguide.com shows the following dimensions for the .300 Whisper:

Case length: 1.40"
Neck id.: .308"
Neck od.: .330"
Neck length: .228"
Shoulder angle: 11 degrees
Body dia. @ shoulder: .369"
Shoulder to base: 1.070"
Body dia. above rim: .375"
Rim dia.: .375"

Which measurements are inaccurate, other than case length?