6.5x47

[Hoier]

Hey guys sorry to ask such a silly question but what is a "no turn" neck for a 6.5x47? I am new to the '47 and am a 6br guy.

 

[jnyfeler]

It's a term used to describe the neck diameter of a chambering reamer relative to the neck diameter of a loaded round using a particular brand of brass. It speaks to the neck diameter that's cut by the reamer and says that the reamer's neck diameter is sufficient to allow you to safely shoot your particular brass in that chamber without the need to turn the necks on the brass.

Insufficient clearance between the neck diameter of the chamber and the neck diameter of the loaded round would not leave enough room for the neck of the cartridge case to expand when fired and freely release the bullet. This insufficient clearance can raise pressures up to and even beyond safe levels. Assuming your chamber is already cut, this insufficient neck clearance condition is remedied by switching to a brand of brass with thinner neck walls or by removing brass from the necks of your current cartridge cases, i.e. turning the necks.

So the term "no neck turn" would also be accompanied by "on Lapua brass" or "on Winchester brass", etc. as it is relative to a particular brand of brass and that brass' corresponding neck thickness.

Jeff

 

[Hoier]

Thanks for the answer Jeff but I meant what is the dimension of a 6.5x47 that would be a no turn.

 

[jnyfeler]

lol, that's not a silly question. And I've got a number in my head, but I'm not sure if it's right, so I'll defer to someone else rather than post the dreaded "I think".

Jeff

 

[Hoier]

Thanks Jeff!

 

[B Mize]

With my brass and bullet they average .290. My reamer is a .293 for no turn brass.

 

[Mega]

I would consider a "No Turn Neck" to be around 0.293" but I think more common would most likely be 0.294" but it still depends on how much clearance you like around a loaded case where some like 0.002" as a bare minimum but most a bit more.

The three chambers I have are 0.286" tight neck, 0.292" no turn and 0.294" no turn. The 0.292" neck allows me to run a no turn loaded round with a neck size of 0.290" (130gr Berger VLD Target or Hunting Bullet) and gives me the 0.002" clearance I prefer to use as with my tight neck chamber. If one likes more clearance then the 0.292" neck allows for a light skim neck turn to create your desired clearance and perhaps improve neck concentricity.

I don't like the 0.294" chamber neck for a target rifle as it gives me too much clearance and no room to improve concentricity without increasing the clearance even further.

For a hunting rifle then the extra neck size may be an advantage for piece of mind.

My target rifles give me well sub 0.2 MOA accuracy. The 0.294" neck chamber is the least accurate of my three.

Just my view on the subject, others may differ in their own opinion.

 

[SDWhirlwind]

My reamer is .294nk for the use of factory Lapua brass at that time. All my current 47L new brass is the older gold box. Supposedly the new blue box is same same in the neck thickness.

 

[Chuckw]

The .292 neck only gives you .001 clearance per side. I believe that is the correct way to measure "clearance" in this case. That is too tight, in my opinion, for applications other than a target rifle. My reamer is a .294 neck and it produces plenty accurate rifles. I think .002 clearance per side is comsidered by most to be a fitted no turn neck and is much tighter than most standard factory chambers. For a .290 loaded round go at least .293 and .294 wont hurt you IMHO.

Chuck

 

[alf]

PT&G considers a .2945" a standard no turn...that's what mine is.

 

[Hoier]

Thanks guys! My new to me rifle is a Stiller Predator in a Masterclass F class stock I might run it as a heavy gun/ F class. It came with 3 barrels a 30br, a 6br and a 6.5x47. The 6.5x47 doesn't look like it has 50 rounds through it. The other 2 barrels look are tight necks.

 

[areaone]

My reamer as per Kiff: .2935 neck, 123 FB, shoots the 123 gr---out of sight. Loaded round is 290--2905.

 

[22BRGUY]

I think to determine this, it is important to measure the neck wall thickness of your brass with a ball micrometer; then multiply that number by 2 (2 sides of the case neck wall thickness all the way around the bullet when loaded; then add atleast .003 to that number and compare it to your chamber neck wall dimension. If those 2 numbers are not at least .003 apart, then the necks need to be turned down to be safe.

Example:
Bullet diameter: .264
Case neck wall thickness: .010 (example)

.264+ .020 (2x .010) = .284 + .003 = .287 maximum loaded round neck diameter to be safe in this example with .010 neck wall thickness.

Hope this helps and hope my math is right

Best Wishes

 

[wildchild]

And then cut a chamber that follows the print... ;D