LRHWAL
Well-Known Member
A question for my future planning so please bear with me and provide any input possible.
My question is what is viewed as preferred clearance over loaded round diameter for a "no-turn neck" chamber?
Here's what I "understand", but please can those of you with the knowledge comment on this?
Clearance seems by most accounts to need to be 3-4 thou (although those who monitor closely, or neck turn for tight necks will go much tighter obviously). Is that a good number to use for "no neck turn" clearance?
Example:
Currently my 300 WM is a case in point. With WW brass my loaded round OD is around 0.333-0.334 (case walls are 0.0125-0.0129"). On that basis would a no-turn chamber be cut at say 0.337-0.338 (assuming I cut a chamber specifically for that WW brass)?
I can't find the SAAMI specs on the net, but Forster on their "Outside Neck Turning Accessory Instructions" page lists them as 0.3397 ("+0 or -0.008" ", whatever that means as it's a pretty wide spread, so that seems to make no sense to me). That's strange to me too as my fired case OD measure 0.340 and there must be some springback in there, making the chamber larger than that (I haven't taken a chamber cast yet and of course it may be outside spec).
What would SAAMI chamber OD in the neck area be for say the .300 WM and .243 Win?
Finally, if I wanted to go to thicker brass for the 300 WM, what brands are likley to be closer to say 0.014" or so? any ideas?
Thanks.
WL
My question is what is viewed as preferred clearance over loaded round diameter for a "no-turn neck" chamber?
Here's what I "understand", but please can those of you with the knowledge comment on this?
Clearance seems by most accounts to need to be 3-4 thou (although those who monitor closely, or neck turn for tight necks will go much tighter obviously). Is that a good number to use for "no neck turn" clearance?
Example:
Currently my 300 WM is a case in point. With WW brass my loaded round OD is around 0.333-0.334 (case walls are 0.0125-0.0129"). On that basis would a no-turn chamber be cut at say 0.337-0.338 (assuming I cut a chamber specifically for that WW brass)?
I can't find the SAAMI specs on the net, but Forster on their "Outside Neck Turning Accessory Instructions" page lists them as 0.3397 ("+0 or -0.008" ", whatever that means as it's a pretty wide spread, so that seems to make no sense to me). That's strange to me too as my fired case OD measure 0.340 and there must be some springback in there, making the chamber larger than that (I haven't taken a chamber cast yet and of course it may be outside spec).
What would SAAMI chamber OD in the neck area be for say the .300 WM and .243 Win?
Finally, if I wanted to go to thicker brass for the 300 WM, what brands are likley to be closer to say 0.014" or so? any ideas?
Thanks.
WL
Last edited: