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Minimum Neck Clearance

What is the minimum neck clearance for a no-turn chamber. A loaded round I'd like to use is 0.270", but the only in stock reamer I can find is 0.272". Is this sufficient clearance, or should I order another reamer?
 
Mine is a .273 and i still turn necks. You need to at least skim cut em to get em consistent if youre talking about a competition rifle
 
Dusty Stevens said:
Mine is a .273 and i still turn necks. You need to at least skim cut em to get em consistent if youre talking about a competition rifle

This will not be a competition rifle, but I want something that will be reliable and safe.
 
Ram said:
What is the minimum neck clearance for a no-turn chamber. A loaded round I'd like to use is 0.270", but the only in stock reamer I can find is 0.272". Is this sufficient clearance, or should I order another reamer?
IMO you're clearance is perfect. I think what Dusty was saying is that he turned for concentricity..not to create more clearance. I don't like to run any tighter than .002" clearance, but some do.
 
Ram said:

What is the minimum neck clearance for a no-turn chamber.


.276 I would think is the absolute minimum for a no-turn chamber.

I assume you're talking about a .243. Normally .003 neck clearance is considered the bare minimum for proper bullet release, anything less will give you problems. So .243+.015+.015 +.003= .276 and you're still running the risk of some of the thicker necks that are around .016-.017 .

You're right at the point where you can buy a new reamer for around $140 or a new neck turner for about $110 https://www.youtube.com/watch?v=ZFkV2thFL5U

Good luck,

Joe
 
For me, 2thou is plenty of clearance, and not excessive.
I would go with the .272, no problem.

For you:
If concerned about safety in it, any neck clearance at all is enough. Of course it's on you to verify this & keep your chamber/ammo clean.
If concerned about accuracy in it, well that's always a balance.
Where you make crooked ammo, tighter clearances lead to chambered tensions. So you could open the clearances to alleviate this and maybe shoot better. Depends on how well you can maintain consistent brass with larger clearances.
On the flip side, where you make straight ammo, you can get away with tighter clearances and brass that lasts a long time with little effort.
That's the balance, and it tips toward the cartridge design and your reloading abilities.
So what's the cartridge?
 
mikecr said:
For me, 2thou is plenty of clearance, and not excessive.
I would go with the .272, no problem.

For you:
If concerned about safety in it, any neck clearance at all is enough. Of course it's on you to verify this & keep your chamber/ammo clean.
If concerned about accuracy in it, well that's always a balance.
Where you make crooked ammo, tighter clearances lead to chambered tensions. So you could open the clearances to alleviate this and maybe shoot better. Depends on how well you can maintain consistent brass with larger clearances.
On the flip side, where you make straight ammo, you can get away with tighter clearances and brass that lasts a long time with little effort.
That's the balance, and it tips toward the cartridge design and your reloading abilities.
So what's the cartridge?

The cartridge is 6x47 Lapua
 
Ram said:
What is the minimum neck clearance for a no-turn chamber. A loaded round I'd like to use is 0.270", but the only in stock reamer I can find is 0.272". Is this sufficient clearance, or should I order another reamer?

I'm guessing you are talking about this reamer: http://www.grizzly.com/products/6-X-47mm-Lapua-Chambering-Finish-Reamer/T10178

About 6 months ago, this very reamer was mislabeled as a .274 and three friends used it in their "no-turn" tactical rifles. All three developed over-pressure signs with their unturned Lapua brass: ejector marks, sticky bolt lift, etc. Their loaded cartridges measured .271 and the chamber necks measured at .272 with a pin gauge... We reamed the necks to .276 and the problem was resolved.

Soooo, I'd recommend a .276 for the 6x47 L with unturned brass and would call .274 the bare minimum.
 
.276 I would think is the absolute minimum for a no-turn chamber.

I assume you're talking about a .243. Normally .003 neck clearance is considered the bare minimum for proper bullet release, anything less will give you problems. So .243+.015+.015 +.003= .276 and you're still running the risk of some of the thicker necks that are around .016-.017 .

You're right at the point where you can buy a new reamer for around $140 or a new neck turner for about $110 https://www.youtube.com/watch?v=ZFkV2thFL5U

Good luck,

Joe

The above also applies to a 6x47. Remember that even the best reamers are +/- 0.0005, so don't take the reamer engraving as gospel. YMMV.
 
I use fitted necks in a 6.5wssm. That is, 1thou total clearance(max)(fully within springback of my brass). No problems at all.
A chamber doesn't cause high pressures, or pressure 'problems'. We do.
 
mikecr said:
I use fitted necks in a 6.5wssm. That is, 1thou total clearance(max)(fully within springback of my brass). No problems at all.
A chamber doesn't cause high pressures, or pressure 'problems'. We do.
Thank you Mike! I knew you would.
Clearance is just that....clearance. As long as the bullet can release, you won't get pressure from clearance! Now, as mike said earlier, if you let the chamber build up with crud that might eliminate that clearance...that's another story.
 

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