Acceptable neck turning variation

[Kevin1990]

Just curious from the perspective of the benchrest and precision crowd. When you neck turn what is an acceptable variation between loaded rounds? I know we're shooting for .0001 and under, but is .0002 acceptable? If you had some pieces between .0003-.0005 would you just cull them and call it good?

I'm just curious on this, I mean it certainly has to matter i'd think as far as bullet release? Then again, I see guys shooting and winning with no turn necks. Also, wondering if some of that variation is just user error.

Thanks fellas

 

[gunsandgunsmithing]

Ime, factory Lapua is within about .0005 or so out of the box and neck thickness consistency has never been proven to be what I'd call a significant factor to br type accuracy. Opinions vary a lot but the results vary less when tested head to head.

 

[neckturner]

I know we're shooting for .0001 and under, but is .0002 acceptable?

If you turn with a decent tool and without rushing it, you'll see .0001 no problem. Also assumes your bullets are uniform.

 

[Kevin1990]

Ime, factory Lapua is within about .0005 or so out of the box and neck thickness consistency has never been proven to be what I'd call a significant factor to br type accuracy. Opinions vary a lot but the results vary less when tested head to head.

Thanks Mike! Reading some old threads on here from 2008 to 2010 people make it sound like you'd be better off culling the entire lot if you have more than .000001 variation lol. I just like to ask because I know opinions can change through experience and testing.


I just checked some loaded 6br with factory lapua and I am seeing .0003 out of the 20 I measured. Just measuring anything I can to try and get a better feel and confidence with this mic.

If you turn with a decent tool and without rushing it, you'll see .0001 no problem. Also assumes your bullets are uniform.

Probably so, but I've got some variation in mine. I was turning while the mandrel was hot and rushing a bit. Just wondering if that variation means anything on paper, pun intended.

 

[shoot4fun]

Heat is a big factor. Rushing the cut and heating up the brass and mandrel are detrimental to good results.
consistent execution of the process is another. I know people that can turn a thousand and keep the neck walls within the .0001 but I'm more in the .0002 camp.

 

[222Jim]

Just don't try to remove too much in a single pass. How much is too much? I get best results when I limit a single pass to removing less than 0.0015" and try for 0.0005" for the final pass.

Brass is funny.........if you try to remove too much in a single pass, it actually "piles up" like snow in front of a snow shovel. That makes achieving consistent results difficult. And keep the neck and arbor lubricated. Then getting less than 0.0002", which is tighter than many people can consistently measure, is achievable.

 

[mgunderson]

Ime, factory Lapua is within about .0005 or so out of the box and neck thickness consistency has never been proven to be what I'd call a significant factor to br type accuracy. Opinions vary a lot but the results vary less when tested head to head.

Some lots this is true Mike. Spent a good amount of time turning necks for br and 308 and that level of tolerance out of the box is crazy talk. Br is one of the more consistent, but i wouldn't say every br lots sre the same.

As a side note. I am a fan of the new cardboard boxes. The neck are super right out of the box.