Dasher Neck Turning?

[Longtrain]

My Dasher reamer has a no turn .2704 neck and has worked just fine in two previous barrels using FF’ed Lapua BR brass. Loaded rounds run at .268 and that gives .0024 total neck clearance.

I just got some Peterson and neck thickness is up a bit, loaded rounds are at .269, that provides .0014 total neck clearance. Loaded rounds chamber without any problem.

Shoot as is? OR turn them to .012” OR fire first to blow the cases out, then turn the necks? Insight is appreciated. Thx.

 

[RICK SMITH]

You might have an extraction issue after firing, due to real little neck clearance. I'd fire a couple and see. If they stick you know what to do from there. I always turn brass before and them go back over them after 3 or 4 firings. I like to have 3.5 to 4 thou neck clearance though.

 

[Dave M.]

Personally, I’d turn everything up front any target 2.5-4.0thou of total diametral clearance. 1.4 thou will work but I think it’s just asking for problems in the future. Also, every gun I’ve ever run 2.0 was less accurate than after I opened clearance up to 3.0+
Dave

 

[Dusty Stevens]

Id turn them before forming

 

[Ray123]

I'd turn them...I use a .272 neck on my reamer so I don't have to.

 

[Longtrain]

I agree with turning them. In hindsight I would have gotten a .272 reamer, but this barrel was sitting on my shelf and was done with others a couple of years ago. Turning them to .012 will keep everything in line with the Lapua, as far as dimensions go. I know that loads may be different due to case capacity. Gives me something to do as the snow flies.

 

[mikecr]

0.0014" clearance might as well be a mile.
The only difference resulting is less working of necks with each sizing cycle.

 

[Ccrider]

You can have .001variance in neck thickness in brass after fireforming.

 

[mikecr]

You can have .001variance in neck thickness in brass after fireforming.

How?

 

[dgeesaman]

My 6BRA is .271 neck and that’s as close as I’ll go with no-turn*. In fact I generally skim all of my brass in that chamber.

*Based on blue box Lapua 6BR brass and Peterson 6BR brass.

 

[Ccrider]

How?

How tight do you think the tolerance is from the factory? Brass moves and grows when fired.

 

[mikecr]

You can have .001variance in neck thickness in brass after fireforming.

This implies that fireforming can cause 1thou thickness variance (broadly, without qualifiers).
Up? Down? Where? How?
I'm sincerely curious about what you specifically mean here.

OP is not shooting a factory 270Win or anything over the counter. It's a 6 Dasher.
He's measuring his stuff, as good reloaders do.
40deg shoulders contribute less to donut growth, and dashers shorten necks, so it would take some bazaar effort to cause a donut problem here.

The only improvement potential with high neck clearances is for relief of chambered pressure points, from excess ammo runout. Don't forget though that it is high clearances and high sizing that led to that runout to begin with. A self feeding loop.
If you fire form your cases to dead straight in a chamber with reasonable clearances, and reasonably size cases, runout will never grow to a point of needing a clearance band-aid. You escape that loop.

As far as safety, any neck clearance is sufficient.
But it's on you to manage that, so failing to do so is purely on you.
IMO, it would take serious stupid to force chamber an interference fitting neck with a bolt action.
A Darwin award follows that.

 

[Ccrider]

This implies that fireforming can cause 1thou thickness variance (broadly, without qualifiers).
Up? Down? Where? How?
I'm sincerely curious about what you specifically mean here.

OP is not shooting a factory 270Win or anything over the counter. It's a 6 Dasher.
He's measuring his stuff, as good reloaders do.
40deg shoulders contribute less to donut growth, and dashers shorten necks, so it would take some bazaar effort to cause a donut problem here.

The only improvement potential with high neck clearances is for relief of chambered pressure points, from excess ammo runout. Don't forget though that it is high clearances and high sizing that led to that runout to begin with. A self feeding loop.
If you fire form your cases to dead straight in a chamber with reasonable clearances, and reasonably size cases, runout will never grow to a point of needing a clearance band-aid. You escape that loop.

As far as safety, any neck clearance is sufficient.
But it's on you to manage that, so failing to do so is purely on you.
IMO, it would take serious stupid to force chamber an interference fitting neck with a bolt action.
A Darwin award follows that.

You did not answer my question. What have you found the variance to be in neck thickness from unfired ammo?

What is the variance in bullet width? How much does neck thickness increase after each firing.

Add these variances in plus the fact that most of us can’t hold .0005 tolerances with our measurements and you see why .0014 is not enough clearance to be comfortable with.

 

[Mulligan]

You did not answer my question. What have you found the variance to be in neck thickness from unfired ammo?

What is the variance in bullet width? How much does neck thickness increase after each firing.

Add these variances in plus the fact that most of us can’t hold .0005 tolerances with our measurements and you see why .0014 is not enough clearance to be comfortable with.

This ^^^^

Lot's of folks trim length, fewer measure and turn or re-turn. Make no mistake, brass flows.
CW

 

[mikecr]

I'll try to answer your questions Cc.
I typically see 1/2thou variance in new necks. Bullets under 0.00002, which is of no concern to me.
Neck thickness does not increase with fire forming. Technically, expanding necks decrease in thickness, and are only downsized back to baseline. Donuts I'll speak on below.

I do measure all necks, and with better accuracy than most reloaders. My selection of cases is based on those with same neck thickness, and no variance of their thickness. These measurements are at 0.0001 accuracy or better, with fixed datums.
With Lapua and Win reloading brass, this buys me ~2 out every 10 cases on average to move forward with. I turn necks for some chambers, but not all.
I don't always need necks to be so good, but thickness/variance there is indicative of case full length quality. I manage my cases below 1thou loaded TIR, and that is one of my limits for further case use.
That might seem a crazy cutoff, but for my sizing/fit plan 1thou TIR is outrageous. It would indicate something in a case's character is wicked, and could throw a shot.

For each chamber I've had control over, I set neck clearance no greater than 1thou.
Been running with 1/2thou neck clearance for my latest chamber, and tested to estimated 0.0001 clearance just for the learning. This is actually a fitted chamber, with 1/2thou clearance from new brass -everywhere.
I have over 80 reload cycles on the brass, at SAAMI max load pressure, with no sizing other than occasional ~1/2 to 1thou shoulder bumps. No body or neck sizing.
With this experimenting I've learned a lot in contrast to magazine articles and folklore.

That brass 'flows' into necks, is not something I see.
Brass is rolled, thick towards thin (up cases) with sizing.
Donut formations or changes, occur with neck upsizing to higher cals, and from heavy body/shoulder sizing. Otherwise, donut thickness is simply that inherent to case manufacture.
Well that's what I see. But I've never chosen long/super low shoulder angle cartridges (like 30-06).
So maybe it's an issue there, I don't know. Won't be for me, I know that.

I don't FL size, anything, ever, so it appears to me that even ~800 reload cycles would not change MY initially turned neck thickness.
There is just no action from me that would move brass up to necks.
And this is why I'm curious about simple fire forming of brass, increasing neck thickness.

I know that the things I do in reloading are different and not required.
But in 48yrs of reloading I never did it for the shooting. I do it for the learning.
I don't shoot varmints or targets because I need to either. I do that for the learning also.
So when someone claims X leads to Z, It's valuable to me when they can describe Y.

 

[Dave M.]

I agree with turning them. In hindsight I would have gotten a .272 reamer, but this barrel was sitting on my shelf and was done with others a couple of years ago. Turning them to .012 will keep everything in line with the Lapua, as far as dimensions go. I know that loads may be different due to case capacity. Gives me something to do as the snow flies.

My girlfriend and I shoot 6 Dashers chambered with the same reamer and I shoot Lapua brass and she shoots Peterson. I shoot 33.1g of RL-15 at 3071fps, and she is using 33.3g of RL-15 at 3042fps. So I think you may have to bump up 0.2-0.3g to get close to your same velocity as now. Unfortunately, in her rifle we were never able to attain my velocities before signs of pressure started. Also, the Peterson brass seems WAYYYY softer. It isn’t uncommon for us to clean her rifle and find tiny bits of brass in the lug lockup area of the action. Also, the Peterson brass will show loose primer pockets before any other concerns.
Good luck,
Dave

 

[Dave M.]

I'll try to answer your questions Cc.
I typically see 1/2thou variance in new necks. Bullets under 0.00002, which is of no concern to me.
Neck thickness does not increase with fire forming. Technically, expanding necks decrease in thickness, and are only downsized back to baseline. Donuts I'll speak on below.

I do measure all necks, and with better accuracy than most reloaders. My selection of cases is based on those with same neck thickness, and no variance of their thickness. These measurements are at 0.0001 accuracy or better, with fixed datums.
With Lapua and Win reloading brass, this buys me ~2 out every 10 cases on average to move forward with. I turn necks for some chambers, but not all.
I don't always need necks to be so good, but thickness/variance there is indicative of case full length quality. I manage my cases below 1thou loaded TIR, and that is one of my limits for further case use.
That might seem a crazy cutoff, but for my sizing/fit plan 1thou TIR is outrageous. It would indicate something in a case's character is wicked, and could throw a shot.

For each chamber I've had control over, I set neck clearance no greater than 1thou.
Been running with 1/2thou neck clearance for my latest chamber, and tested to estimated 0.0001 clearance just for the learning. This is actually a fitted chamber, with 1/2thou clearance from new brass -everywhere.
I have over 80 reload cycles on the brass, at SAAMI max load pressure, with no sizing other than occasional ~1/2 to 1thou shoulder bumps. No body or neck sizing.
With this experimenting I've learned a lot in contrast to magazine articles and folklore.

That brass 'flows' into necks, is not something I see.
Brass is rolled, thick towards thin (up cases) with sizing.
Donut formations or changes, occur with neck upsizing to higher cals, and from heavy body/shoulder sizing. Otherwise, donut thickness is simply that inherent to case manufacture.
Well that's what I see. But I've never chosen long/super low shoulder angle cartridges (like 30-06).
So maybe it's an issue there, I don't know. Won't be for me, I know that.

I don't FL size, anything, ever, so it appears to me that even ~800 reload cycles would not change MY initially turned neck thickness.
There is just no action from me that would move brass up to necks.
And this is why I'm curious about simple fire forming of brass, increasing neck thickness.

I know that the things I do in reloading are different and not required.
But in 48yrs of reloading I never did it for the shooting. I do it for the learning.
I don't shoot varmints or targets because I need to either. I do that for the learning also.
So when someone claims X leads to Z, It's valuable to me when they can describe Y.

Those are some truly amazing specs for brass you mentioned above. I’d need to be a millionaire to hold half of those specs because I’d have to throw out 99% of my brass. LOL.
Dave

 

[Ccrider]

I'll try to answer your questions Cc.
I typically see 1/2thou variance in new necks. Bullets under 0.00002, which is of no concern to me.
Neck thickness does not increase with fire forming. Technically, expanding necks decrease in thickness, and are only downsized back to baseline. Donuts I'll speak on below.

I do measure all necks, and with better accuracy than most reloaders. My selection of cases is based on those with same neck thickness, and no variance of their thickness. These measurements are at 0.0001 accuracy or better, with fixed datums.
With Lapua and Win reloading brass, this buys me ~2 out every 10 cases on average to move forward with. I turn necks for some chambers, but not all.
I don't always need necks to be so good, but thickness/variance there is indicative of case full length quality. I manage my cases below 1thou loaded TIR, and that is one of my limits for further case use.
That might seem a crazy cutoff, but for my sizing/fit plan 1thou TIR is outrageous. It would indicate something in a case's character is wicked, and could throw a shot.

For each chamber I've had control over, I set neck clearance no greater than 1thou.
Been running with 1/2thou neck clearance for my latest chamber, and tested to estimated 0.0001 clearance just for the learning. This is actually a fitted chamber, with 1/2thou clearance from new brass -everywhere.
I have over 80 reload cycles on the brass, at SAAMI max load pressure, with no sizing other than occasional ~1/2 to 1thou shoulder bumps. No body or neck sizing.
With this experimenting I've learned a lot in contrast to magazine articles and folklore.

That brass 'flows' into necks, is not something I see.
Brass is rolled, thick towards thin (up cases) with sizing.
Donut formations or changes, occur with neck upsizing to higher cals, and from heavy body/shoulder sizing. Otherwise, donut thickness is simply that inherent to case manufacture.
Well that's what I see. But I've never chosen long/super low shoulder angle cartridges (like 30-06).
So maybe it's an issue there, I don't know. Won't be for me, I know that.

I don't FL size, anything, ever, so it appears to me that even ~800 reload cycles would not change MY initially turned neck thickness.
There is just no action from me that would move brass up to necks.
And this is why I'm curious about simple fire forming of brass, increasing neck thickness.

I know that the things I do in reloading are different and not required.
But in 48yrs of reloading I never did it for the shooting. I do it for the learning.
I don't shoot varmints or targets because I need to either. I do that for the learning also.
So when someone claims X leads to Z, It's valuable to me when they can describe Y.

You must be a machinist or have a similar background. I can not hold the tolerances that you hold or measure that close. Also, your process is a lots different than what I do. I am not using a tight chamber. I full length size each time using whatever neck bushing the paper tells me is best.

I agree that the less you move the brass, the less it seems to grow. Nonetheless, I am comfortable annealing after each firing and moving the shoulders back at least .002.

 

[Longtrain]

My girlfriend and I shoot 6 Dashers chambered with the same reamer and I shoot Lapua brass and she shoots Peterson. I shoot 33.1g of RL-15 at 3071fps, and she is using 33.3g of RL-15 at 3042fps. So I think you may have to bump up 0.2-0.3g to get close to your same velocity as now. Unfortunately, in her rifle we were never able to attain my velocities before signs of pressure started. Also, the Peterson brass seems WAYYYY softer. It isn’t uncommon for us to clean her rifle and find tiny bits of brass in the lug lockup area of the action. Also, the Peterson brass will show loose primer pockets before any other concerns.
Good luck,
Dave

I never got over 3K with my Dasher. I ran 32.5 grs of Norma 203B with Berger 108’s, which got me 2960 fps out of a 30” Brux. I had no pressure issues, but beyond that I saw some initial signs. Accuracy was so good that I left well enough alone.

I just installed a new barrel as my velocity has dropped along with an increase of copper as the throat lengthened. I ended up with 33.3 grs of N140 under a Bison 103, which got me back to my original mid 2900’s. Had about 2200 rounds on it, may have lasted longer, but with one on the shelf, I retired it for now.

It will be interesting what the Peterson does and how it performs. I turned them to .012, so that issue is done. Their weight is pretty uniform, we’ll see what’s what come Spring time. They headspace at 1.235” and my sized fired Lapua is 1.242, it will take a couple of firings to get them up to fighting weight. We’ll see, they are awful pretty though.