6BR Tight Neck - Symptoms of being too tight?

[RonAKA]

I have measured my fired cases and get 0.2694" near the mouth of the case, and 0.2714 near the shoulder. With a 0.001" allowance for spring back, that suggests a chamber neck of 0.2724" tapering to 0.2704". Don't have any loaded rounds on hand, but I know some have measured 0.2697". That potentially leaves a clearance of as little as 0.0007". If so, is that too little? What would the symptoms be of too little clearance in the neck?

 

[Yellow11]

If a bench mark is of any help, my 7/300 WSM has a neck diameter, on a loaded round, 2 thou" less than the chamber's reamer, viz, loaded round 0.310", chamber neck diamnsions 0.312".

Fired case measures .310" and this is bushed down to .308" before reloading

 

[treeman]

A pretty good way to check is to put a bullet into a fired case. if you feel any resistance at all there is to little clearance. I would shoot for at least .002" my $.02, Darrell

 

[Jeff Peinhardt]

case may be tight going into chamber - DO NOT FIRE THESE ROUNDS!

Slightest bit of carbon ring or dirt on neck will cause tightness - look for scuff marks on necks

with 0.0004 to .0007" clearence you will get a black ring around (powder ring) the neck 1/16" to 1/8" from end of case - not the typical sine wave look.

Flyers!

 

[dennisinaz]

I have a 260 Rem with a .294 neck. It is supposed to be a no-turn neck but it's not. With either Lapua 243 or 308 brass, I have to neck turn or I get flyers. I can't get fliers to go away until I have .003-.004 clearance. With .004 being better. I am rechambering because of this- I had a new reamer ground with a .297 neck and hopefully, this will let me shoot without turning.

 

[RonAKA]

A pretty good way to check is to put a bullet into a fired case. if you feel any resistance at all there is to little clearance. I would shoot for at least .002" my $.02, Darrell

I tried some 1X fired cases and 5X fired with two different bullets. First with the Bart's which has a significant pressure ring, You can't put the bullet straight into either case. But, if you angle it some to get it started it will go in. After it is in and back a bit, then it slides freely. However when you pull it straight out there is a significant resistance when the ring gets near the mouth. It stops, but then comes out with a sudden "pop". Cases behave about the same, except the 5X is a bit tighter.

With a Sierra that has no pressure ring and measures about 0.2428", it is a tight sliding fit in the 1X case, and a bit easier in the 5X.