To neck turn or not

[Fuj]

I prefer a no turn, and order reamers to that effect. Even though
I order a certain number, I do a chamber cast to know what I really
have.

 

[gunsandgunsmithing]

I prefer a no turn, and order reamers to that effect. Even though
I order a certain number, I do a chamber cast to know what I really
have.

For my testing, I've simply been using a tight neck chamber reamer, then opening the neck up with a chucking reamer of the size I want. Works fine but adds a step plus indicating it back it.

 

[6BRA]

Another aspect of all this is that the newer Lapua brass has been very good, like .0005 good. Frankly, that shouldn't be terribly hard to improve upon by a little bit but not everyone is getting results that good with neck turning. In fact, to save time, I've paid for brass turning that wasn't any better than that. Add in, someone new to the process, and they may get results not that good, even.

All this is pretty fresh on my mind because I have a friend who I've chambered bbls for that didn't shoot well last season. The guns shot great in practice mind you...in good conditions. Regardless, because he went to no turn chambers, guess what he blames his poor shooting last season on...Yep, you guessed it. So now he has bought all new neck turning equipment to "fix" the problem, along with new annealing equipment. Yep, first few pieces a full thou smaller or larger(I forgot which) than the intended mark. Lol! Well, there's a learning curve here. I'm not sure where that problem came from because I sat down with him and we set up one of his turners and turned a few pieces. They were pretty much spot on when they left here....There is no harm in doing it RIGHT, if you think it matters. But if you're learning the process, it might do more harm than good and we start debating then, how much matters. (Isn't that what we were already doing) Lol! Now, I guess a good test might be to shoot those to see how much difference it makes, fwiw. He struggled with multiple guns...some no turn and some not.

Bottom line, you do have to be able to shoot the difference and you can't learn that in perfect conditions, then go shoot in the wind expecting to win.

I'll say this again...you buy wins at the practice bench, not at the keyboard and not by buying new gadgets. Absolutely nothing wrong with making everything as near perfect as possible either but you still have to be able to shoot the difference and that only happens with GOOD practice. I'm fortunate to have a home range and I fully intend to burn up at least one barrel over the winter. Components have limited some people's GOOD practice, including mine but I'm fixing that too...as best I can.

Another way to look at this is...lets say brass out of the box does have .0005 TIR. Now, does making that brass .0004"(+/- .0002)give a 20% reduction in group size? Well, I wish it did because I can generally hold mine to +/- .0001

Where does runout,...tir...come into play with turning necks and neck wall thickness? I have never seen new Lapua hold a case wall neck thickness of .0005 across 5 cases let alone a box of 100. The case neck wall thickness will be at normal .001 variance per each pc of brass. Has nothing to do with runout?

 

[ebb]

The explanation I heard back in the day was that a uniform neck released a bullet straight and a neck with thin spots would let the bullet come out of the case pointed toward the thin side. I talked with a close range BR national champ at the St Lewis bench rest club, he said that if the bullet was into the lands how could any of that matter the bullet was straight and could only enter the bore straight .

 

[gunsandgunsmithing]

Where does runout,...tir...come into play with turning necks and neck wall thickness? I have never seen new Lapua hold a case wall neck thickness of .0005 across 5 cases let alone a box of 100. The case neck wall thickness will be at normal .001 variance per each pc of brass. Has nothing to do with runout?

I'm not talking bullet runout, for starters. I'm talking the neck over a bullet, as it will serve as a mandrel in this instance. If it's round within a half thou, that's what I'm talking about, exactly... Your lots may not be that good,..I'm impressed with what I've measured, too, but it's been over multiple recent lots, fwiw. Bottom line is, can you shoot the difference or not. If you feel you can, then turn necks..by all means. I'm not telling anyone not to do what makes them feel better. Now loosen up. It'll be ok whether you choose to turn or not. Up to you my friend.

 

[Dave M.]

Bart Sauter just whipped us the second year in a row shooting at the Tack Driver III shooting no turn chambers. 6 BRA last year and a 6 PPC this year. I have chambered a lot of no turn 6BR barrels and had no complaints about accuracy. I don't think it's necessary except for an all out BR rifle. You do need enough neck clearance though or you could have some inconstancy.

I shoot two tack driving 6 dashers and both have .2715” necks and I don’t turn the Lapua brass for either of them. Those rifles racked up two state championships this year for my girlfriend and I, and numerous others wins. Not to mention my dasher now has 4370 rounds on the barrel and the last three matches it shot:
599-32X
599-38X
598-35X
And also shot a fairly remarkable 599-48X at the beginning of the year.

 

[Ccrider]

Bottom line is, can you shoot the difference or not.

This sums it up on a nutshell. Test for yourself and find your own truth.

 

[gunsandgunsmithing]

This sums it up on a nutshell. Test for yourself and find your own truth.

Fwiw, I just measured 10 random loaded cartridges. I took two measurements from each, rotating 90 degrees.
Here's what they measured. They are Lapua 6.5 Grendel cases that have been necked down to 6. I shoot them in a .2745 chamber and have 6 firings on them.

 

[Ccrider]

Fwiw, I just measured 10 random loaded cartridges. I took two measurements from each, rotating 90 degrees.
Here's what they measured. They are Lapua 6.5 Grendel cases that have been necked down to 6. I shoot them in a .2745 chamber and have 6 firings on them.
View attachment 1383484

What do the numbers represent?

 

[gunsandgunsmithing]

What do the numbers represent?

The first and second number(l-r) is neck diameter at two points, rotated 90° from the other on 10 loaded rounds. The far right number is the difference and at the bottom is the extreme difference of the smallest to largest neck diameter over the 10 pieces measured and the extreme spread was .00055, or a tad over a half thou.

This is unturned brass that has been necked down and fired 6 times. The diameters were taken over the pressure ring of the bullet seated in each. Very good numbers, albeit a small sample size given. I've checked a bunch over the last few years and this has been pretty typical from newer lots of Lapua 6.5 Grendel brass.

 

[6BRA]

Regardless if a factory chamber or custom chamber with bullet deep into rifling, neck wall thickness has a relationship to neck tension. If you feel that a bushing die/bushing die bulge and no neck turn brass work. Have at it. If you feel that a even necks all the way to the shoulder junction benefits have at it. If you feel that thinner neck walls also decrease neck tension, have at it. Just feel good about what you do....and be sure you can shoot the difference as "they say". And even if you cant....it just looks cool. Kind of like a sports car next to a gremlin/pacer.