No Turn-VS-Turned Necks

[Hal]

When I measured the necks on 200 Lapua 6MM BR cases the most they varied was .001, from .0115-.0125. The average case varied .0005-.0006

I read some of the guys use a No Turn neck reamer. How much better if any, does a tuned neck shoot than a no turned neck?

Do any of the long range , 600-1000 yds.target shooters use a no turn chamber on the 6mm Dasher sized cases?

Hal

 

[jbarnwell]

Hal, I've had rifles configured both ways and honestly I couldn't tell any difference, but I don't shoot at 1000 yards either. For my shooting, the convenience of not turning the necks is right for me. Just my 2 cents.

 

[rpierce]

I dont turn my necks and my 6brx shot a 1600 120x last fall on the fclass target out of 1600 possible. The accuracy is insane. Its the most accurate 600 yard cartridge Ive ever shot. I dont think the gains from it would be worth my time. I shot 10 shots into .3" at 200 yds without turning necks. My ex girlfriend also shot a .110" six shot group at 100 yds with it. It was her first time shooting a gun like that. I had some rounds to get rid of and let her do it for me. After she shot the group I told her she would be shooting in the next 2 600 yd state championships the following weekends. She got top 10 in her first match and 3rd or 4th in the second match of her life. The part thats hard to admit is on the last relay her score was higher than mine ;D She didnt let me live that down for a while.

 

[johara1]

Neck turned cases,it centers the round in the chamber.uniform neck tension and more uniform bullet release. Smaller groups and less vertical at 1K............. jim

 

[Hoier]

Jim

What size neck do you run?

 

[markr]

If your reamer cuts your chamber with 2-3 thou clearance of the brass/bullet combo that you are going to use, and the appropriate neck sizer is used......I......don't believe that a million reounds downrange would prove any difference in real accuracy.

 

[Laurie]

I read some of the guys use a No Turn neck reamer. How much better if any, does a tuned neck shoot than a no turned neck?

You're maybe mixing two related issues up a bit here. Running a no-turn neck chamber doesn't mean the user doesn't do any neck-turning, rather that the chamber is designed for brass close to factory dimensions. Specifying a 'tight neck' chamber normally means fairly serious thinning of the neck is needed and out of the box factory brass either doesn't fit at all, or if it just does, has inadequate and potentially dangerous clearances. The process of converting .220 Russian cases into 6PPC for short-range bench rest guns usually involves pretty radical neck-turning, reducing neck thickness values from ~0.012" to ~0.0085" and using a 0.002-0.003" overall clearance, ie 0.001 to 0.0015" gap between neck and chamber wall at any particular point.

Some cartridges in some applications perform better when ultimate precision is required, but it's generally believed that 6BR and its improved offspring don't show commensurate gains for the work and other issues involved in running with such thin necks and tight clearances, hence the popularity of 'no-turn' chambers that give less clearance than SAAMI or CIP specified values but still allow brass with dimensions at the upper end of the allowed tolerance values to be used safely. It does rely on the brass being very consistent around one figure - hence the 'upset' when Lapua reduced its neck wall thickness by around 0.001" a couple of years ago and the references to differences between 'gold box' (old, thicker) and 'blue box' BR (recent, thinner) brass, the latter creating a little too much clearance for many no-turn neck chamber users' liking.

However, specifying a no-turn chamber doesn't mean the user will never turn necks for it - clean-up turning is commonly applied for the reasons that people have already given. Another way of doing it with very good closely toleranced brass is to measure necks carefully at say three points and batch them by (a) the overall range they fall in, eg 0.0115" to 0.0120" and 0.0121" to 0.0125" in your brass, alongside (b) applying individual case consistency criteria, eg three readings around the neck that are within a say 0.0003" range. Those cases that fail to make the grade can be either given a light neck-turn to make them comply with the batched brass or used for practice / short-range rounds. You often find that the slightly out of spec stuff produces ammunition that shoots just as well as the fully prepped stuff at shorter ranges. The alternative is to measure a good size sample of the brass as you've done and turn everything small amounts to give consistent around the neck values close to the smallest readings you got.

 

[johara1]

I use a .266 neck and turn brass and turn first to .0106-7 not to picky for fire forming. After the first firing i then turn to .0102, very consistent vertical when i anneal every time. .... jim

 

[Hal]

Thanks for the help.

Hal

 

[T 700]

I have had both, A tight neck and No turn. I also shoot 1K benchrest and as far as i am concerned i will never go back to a turned neck. the no turn shoots as good as the TN. I am getting groups in the high .1( on good days) to low .2s with the No turn at 100yds. The rifle i have now shoots better at 1K than the Tight neck. To me it is not worth the trouble.

T 700

 

[johara1]

T700, I turn the necks and my groups run in the zero's and low one's. At 1K groups are 3-4" range some lower and some bigger. Is it worth it? if you want to win, you better do everything you can........jim

 

[Erik Cortina]

The part thats hard to admit is on the last relay her score was higher than mine ;D She didnt let me live that down for a while.

I guess this is what she gets for making fun of you Ryan! ;D

My ex girlfriend...

 

[Erik Cortina]

The reason I turn necks is because if things don't go so well, I want to at least know I did all I could to prepare.

 

[Laurie]

The reason I turn necks is because if things don't go so well, I want to at least know I did all I could to prepare.

There is a lot of truth in that. I think it was Henry Ford who said that half a company's advertising spend doesn't work, but nobody knows which half. Case and bullet preparation may be a bit like that. You often feel that you HAVE TO DO EVERYTHING or else you'd worry yourself sick that you're throwing points away just to save a bit of time and effort on the margin.

 

[johara1]

Laurie, It's like some are some what lazy and try to justify the lack of an operation. If you go to a match and you have no chance of winning why go, you have to believe in your self and your equipment. Some also sand bag to stay in a lower class so they can win and i saw this many times in service rifle. Shoot with the best with your best, the Marine Corps taught me that a long time ago. This is the same in any discipline........... jim