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Tight-neck brass thickness - TARGET PICS UP

Just finished my first chambering job. My 6XC reamer cuts a 0.272 dia. neck. How much clearance do I need for proper bullet release? I've heard that 0.004" is minimum. What's the consensus?
Dave
 
Re: Tight-neck brass thickness

Depends on what your using the rifle for? .004 is fine for a hunting rifle. Lots of boltgun match shooters like .001 to .002
 
Re: Tight-neck brass thickness

0.004" is about minimum for a gas gun, and fine for a hunting / casual shooter, maybe for competition bolt gun too if everything else is done well.

I've found my 6's work best with just 0.011" - 0.012" neck wall thickness so I might be working with 0.005" or more yet I can still shoot X's at 600 & 1k if I do what I ought to every time.

You'll know once you start putting rounds down range whether your work is satisfactory. What's your intended use and with what bullet(s)? Keep us informed please about what you see on target.
 
Re: Tight-neck brass thickness

I turn my Lapua brass to .0105 for a .266 necked 6 Dasher. That gives me .001 all the way around.
 
Re: Tight-neck brass thickness

I intend to use the rifle for F-Class. It's built on a Tikka T3 receiver. Am awaiting a scope base for completion. Will report results ASAP.
 
Re: Tight-neck brass thickness

My 6XC reamer cuts a 0.272 dia. neck. How much clearance do I need
===
make a dummy case up with the brass your actually using than mike the neck with your intented bullet in ...

i don't think more then .0025 clearence is needed
 
Re: Tight-neck brass thickness

If its a no turn neck,then you really dont need to turn your necks but a mere dusting of the neck to true it.You dont have to make it completely clean but about 70-80 percent clean is good enough.With a .272 neck using new brass you should be able to just do the cleanup to get the high spots unless you are forming 6xc from some other cartridge,then it may thicken the necks slightly during the forming operation.I have a .272 neck gun and I have more room now with the new blue box brass that I dont even clean them up.
 
Re: Tight-neck brass thickness

Don't know about long bullet shooters, but in the short range benchrest game, there has been a trend, among some top shooters to increase total neck clearance to somewhere around .003 (.0015 per side), or a little less. I have tried this, and it seems to work, but if I were ordering a new reamer, I would spec, the neck a couple of thousandths larger to make up for the lost brass, and a little more. Brass that is around .008 is a little thin. My current chamber neck diameter is .062. My next action will have a spring plunger ejector and IMO a thicker neck will take the hit better. I have heard that .30 cal. 1,000 shooters can get better results with a clearance of .005 (I think that is the number.)
 
Re: Tight-neck brass thickness

The reamer I used had been reground to actually cut a 0.272" dia. neck chamber. My new Norma brass with a bullet inserted measures 0.272". Thus the need to shave the necks. I bought the reamer on this forum. I knew it was used but was not told it had been modified. Other-wise, everything else looks OK. Buyer beware!
 
Re: Tight-neck brass thickness

Well, the scope base arrived yesterday and I hit the range bright and early this AM. On break-in, the first 5 shots went inside an inch. The next two 5 shot groups averaged 0.516". I guessed at a load of 38.0 gr. of RL-17 and a 107 SMK jammed .015" into the lands. I used brass that was shaved to give me 0.004" neck clearance. The last two groups were somewhat round with no obvious fliers. This usually means I'm on the right track and groups will get better with tuning!
All-in-all, I'm happy with my first chambering job.
Dave
 
Re: Tight-neck brass thickness new target pics

Shot with 107SMK's and 0.4 gr. progression of IMR4350. Looks like it's gonna shoot!
 

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