How much neck clearance?

[Wheres-Waldo]

Im running a .292" neck in 6.5x47AI

A loaded round measures .290" with factory unturned cases.

Should I turn them down 1 or 2 thou?

 

[Country]

Re: How much neck clearance?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Wheres-Waldo</div><div class="ubbcode-body">Im running a .292" neck in 6.5x47AI

A loaded round measures .290" with factory unturned cases.

Should I turn them down 1 or 2 thou? </div></div>
Well the clearance of .001 alaround is OK for a bolt action . However the factory neck may not be very concentric. So a slight turn to clean up say 75% of the neck surface might give more even neck tension and better seating concentricity . This may or may not result in better accuracy it is hard to say.
Ofcourse we are presuming that the chamber is exactly .292.
If they fit I would try them as they are and then try a batch that has the necks cleaned up 75% and only partial size the necks so you leave a small unsized section of the neck just above the shoulder to aid the neck staying right in the center of the chamber after fire forming.
Then you don't ever size that part again.
It requires bushing neck dies and body sizing dies. To do this.
You can also use a Lee collet die with a washer under it to partial neck size.

 

[Victor N TN]

Re: How much neck clearance?

Have you cast and measured the chamber yourself? Sometimes things are labeled one thing when they may or may not be. Benchrest chambers are often .002" total clearance (.001" per side). But you better keep the chamber & throat clean.

 

[308sako]

Re: How much neck clearance?

Deleted in protest!

 

[rmfield]

Re: How much neck clearance?

For what it is worth, a no turn neck reamer is usually designed at about .002 per side (.004 total).

 

[Country]

Re: How much neck clearance?

I have been running a match chambered 308 W that way for many years and sure you do have to return now and then to keep the necks the right diameter and keep things nice and clean but I don't find it a lot of work for the amount of shots I fire but if you were shooting hundreds per week then it could become harder work .
Thats why you only turn about 75% of the neck area to start with
because it will not be long before you turn again just to clean them up and eventually they turn up 100% .
Its something that you have to try for yourself and go from there.
Tight necks can cause trouble in a hunting rifle if a bit of rubbish gets in the chamber or on the round while out in the forest.
I once had a jam up and it turned out to be one single kernal of unburnt powder that had adheared to the case neck during handling or reloading . I could have just jamed it in with extra bolt force I guess but I new it must be a bit of trash so I did not want to ding up the neck of the case. If it was a shot at a big trophie then I might have tried to jam it in.