BR Discussions > Centerfire Discussions

Neck size diameter

(1/4) > >>

John K:
Hello everyone,
My first post here so please bear with me.
I am having a rifle barreled in 308 with atight neck .
How much under my chamber neck diameter should I turn my brass
for the initial fire forming?

Many thanks

phil:
HI,
   Turn your necks to achieve a clearance of 1 1/2" to 2 thou. under your chamber neck dimension.
   This should be measured by seating the bullet of your choice in the turned neck and then measuring
   the outside diameter of the  neck where the bullet base sits.

Phil

John K:
Thanks Phil,
Ill start there
Much appreciated.

Mr. Jeffery:
Hi Guys,
My first post here also.

Im curious about this as well. Is there a set standard to neck clearance inside the chamber?  Does this vary from caliber to caliber? My savage 10 (in .308) leaves my cartridges very dirty on the necks after firing whereas my weatherby vangaurd ( also .308) does not. Both rifles are discharging the same cartridge. unturned unmodified federal brass. Of course one wont accept the other but that is beside the point.

I ASSUME that one tries for the least amount of clearance as possible? The less the neck expands at time of discharge the better?  Correct me if I am misguided. I am only playing with this in my own head.

DanO:
As was stated above neck clearance of .002” is a good target.
If you accurately measure the brass from each chamber you will see how much it differs from each other.
We normally measure the neck, shoulder and base dimensions of the fired and sized brass as the way to match up the sizing die to the chamber. One measurement that doesn’t get the attention it should is the shoulder (tapered part) bump back. It is common to see the dimensions over sized which effects the headspace clearance on sizes brass.
In a target type rifle this should again be in the .002” range of bump back. In a hunting rifle a bit more bump back is recommended to handle adverse environmental conditions.
The closer you can match the sized brass back the chamber dimensions the better it aligns the projectile to the bore.

Navigation

[0] Message Index

[#] Next page