Tight neck benefit''s

[fm1947]

What are the benefits and why, lets say a .288 neck on a 6.5x47L or 30BR .330 neck

 

[RGRobinett]

What are the benefits and why, lets say a .288 neck on a 6.5x47L or 30BR .330 neck

Hypothetically, to create uniform neck-wall thickness, thus assuring conentricity between the loaded round (bullet) and the axis of the bore. RG

 

[fm1947]

I figured as much but just went with what others are using knowing it has all been tested, but lets say since I know you being a top authority of the 30BR, a person chambered it same as your reamer BUT went with a common 30 cal neck like the .308 at .342 what would the result be if then he also turned necks to get neck concetricity.

 

[wapiti25]

when the clearance between the case neck and the chamber is large you stretch the brass more and may cause more of a chance to have run-out on the bullet. you will have neck splits if you do not anneal often.

 

[fm1947]

makes sense to me thanks.

 

[alf]

Hypothetically, to create uniform neck-wall thickness, thus assuring concentricity between the loaded round (bullet) and the axis of the bore.

And the resulting even bullet release.....

 

[AlNyhus]

Another downside to excessive neck clearance is chamber sealing. Chamber sealing is dependent on the case necks expanding and preventing the gas from getting lower than the neck/shoulder junction. Once you get too big with neck clearance, it takes longer for the necks to seal as they have to expand a greater distance to reach the wall of the chamber neck area. As the necks are expanding, the pressure is decreasing as the bullet goes up the bore and the chamber, in effect, gets 'bigger' (because the 'chamber' now includes amount of bore behind the moving bullet).

How much neck clearance is too much depends on a lot of things..neck length and powder burn rate being two big factors. There is a point of diminishing returns (and increased problems) as you go both directions with neck clearance.

Good shootin'. -Al

 

[4xforfun]

I guess I would answer you question with another question....Why do ALL short range competition benchrest guys use neck turned brass in tight neck chambers?

I know one thing, they DON"T do it cuz it's fun to do!! ;D

 

[fm1947]

thanks to all , Al, that I didn't know I wanted to verify if my thoughts were right on the reaon behind it all , been shooting VFS for 3 years and turning necks is not something I look forward to, thanks every one.

 

[PALarson]

I always like to have 2 to 3 thou clearance, I needed a reamer that I didn't have and borrowed one from a friend. It turned out to have a jump of about 1

 

[PALarson]

To finish the jump was 12 thou and shot great. As has already been mentioned the real down for large throat is brass life.
Paul Larson

 

[fm1947]

thanks