Neck turning question - Question on Lapua brass

[Varmint Hunter]

Am I going down a rabbit hole here with no returns? I'm not using this ammo in competition but rather in production made rifles for hunting. I do like to have very accurate ammo and will do what I can to make it as accurate as possible. I wasn't considering neck turning because of tight chambers in competition rifles. I was only seeking concentric brass and an equal amount of grab on the bullet all the way around. Was also hoping to reduce run out. I was thinking that the concentric brass would be more true coming out of the sizing dies. Especially if you were using bushing dies.

I wouldn't even consider turning brass for a production rifle. The chamber neck could already be very generous in diameter. Turning your case necks down would only increase the clearance which might not be helpful.

If you decide to turn some necks, only turn down 1/2 of them. This way you can try the same loads in turned and un-turned cases. Report back here with your findings.

It has also been discovered that brass with uneven neck wall thicknesses usually have uneven shoulder or body wall thicknesses, or so I have read. If that's the case, there isn't anything that can be done about those variances.

The easy button is to just buy quality brass. (but testing with a few cases won't hurt)

Good luck either way.

 

[MarkInPA]

I wouldn't even consider turning brass for a production rifle. The chamber neck could already be very generous in diameter. Turning your case necks down would only increase the clearance which might not be helpful.

If you decide to turn some necks, only turn down 1/2 of them. This way you can try the same loads in turned and un-turned cases. Report back here with your findings.

It has also been discovered that brass with uneven neck wall thicknesses usually have uneven shoulder or body wall thicknesses, or so I have read. If that's the case, there isn't anything that can be done about those variances.

The easy button is to just buy quality brass. (but testing with a few cases won't hurt)

G

"I wouldn't even consider turning brass for a production rifle. The chamber neck could already be very generous in diameter. Turning your case necks down would only increase the clearance which might not be helpful." Good point.

"If you decide to turn some necks, only turn down 1/2 of them. This way you can try the same loads in turned and un-turned cases. Report back here with your findings." Experiment for myself and find out what happens. Good idea.

" It has also been discovered that brass with uneven neck wall thicknesses usually have uneven shoulder or body wall thicknesses, or so I have read. If that's the case, there isn't anything that can be done about those variances." I've read that too. That's why I have one of these devices and use it.

This all sounds like good advice from someone who knows a thing or two. Thanks.

 

[Hard rock]

The best thing I ever did for eliminating run out and to improve concentric necks , is change to bushing dies with no expander and believe me I have tried everything . This does work best with LAPUA brass where no neck turning is necessary, for hunting loads , I get nearly 0 runout . I use to turn necks and never seen a gain with run of the mil brass win, rem etc.The only time it has become necessary is when necking down from a larger cal to a smaller cal and that would be from 30 cal to 6.5 or 25 cal ,or more.

 

[Coyote Shadow Tracker]

IMO might as well do a 100% percent clean up since you're already doing the work. but a skim turn is fine also. If your cutter matches the shoulder angle then by all means cut into the shoulder a little. It helps mitigate brass flow and possibly donuts.

View attachment 619435

YOU DA MAN!!!!!!!!!!!!
Love those necks.
We should talk some time
Len & Jill

 

[MagnumManiac]

This is how I have always prepped my necks for LR & ELR shooting.
My neck measurements are worked out FIRST on the brass I choose to use. Reamer print is then made. I aim for .003" clearance, including .0005" springback.
All of my brass necks are turned identically in each batch.
I only size 80%-85% of my neck length, I turn exactly to the end of this measurement and I only turn enough to give me the desired clearance and complete clean up.
I have the above Redding case neck gauge measuring set-up, absolute must-have for this, I also have other ball end mics, pin gauges and sized broaches, but you may not need them.
I found that 'cleaning up' necks for SAAMI chambers was a waste of time, so was measuring run-out, measuring CBTO and other precision oriented steps.
The clearances involved are just too large to matter…

If you 'feel' you get better accuracy or precision, then continue, but if you get passed all the noise by shooting 3 10 shot groups, your precision will most likely be average, just saying.

I do not neck turn on large SAAMI chambers, but if I find it necessary, I will skim turn to clean up 80% of the neck.
SAAMI hunting rifle chambers, unless 'Match', are too wish washy for precision loading, including those that CLAIM are precision…

Cheers.

 

[marc357]

I don't believe there is any benefit to turning necks for a SAAMI spec chamber. I believe it is only beneficial if you have a custom "tight-necked" chamber (where it may actually be required for your ammo to fit).

 

[Justice1327]

I don't believe there is any benefit to turning necks for a SAAMI spec chamber. I believe it is only beneficial if you have a custom "tight-necked" chamber (where it may actually be required for your ammo to fit).

Dont necessarily disagree. But what about consistent neck /bullet interference fit? Having a thicker side of the neck interferes with that consistency right?

 

[ntsqd]

I see two reasons to turn necks; To make the brass fit a tight necked chamber, and to make the neck a uniform thickness. Not likely to see a tight neck chamber in a production rifle. If after turning there are still un-machined patches on the neck then it isn't a uniform thickness.

 

[MagnumManiac]

Dont necessarily disagree. But what about consistent neck /bullet interference fit? Having a thicker side of the neck interferes with that consistency right?

Necks expand very early in the combustion sequence, so, having uniform neck thickness is virtually moot.
Many believe the neck has 2 jobs; to hold the bullet prior to loading AND guide the bullet from ignition to throat and rifling engagement.
Have seen this written more times than I can count, it simply is wishful thinking…bullets are free to move as soon as the neck expands, which occurs even with a primer blast alone.
I have run tests with turned necks, unturned necks, shallow seating of .050", and not once did it make a difference. The only thing that does make a difference when tested over the Pressure Trace, was HOW MUCH it affected start pressure.
In all of my pressure testing the number one thing for excellent loads is high start pressure that is gentle, high start pressure that is erratic and harsh is detrimental, as is too much neck interference.
If you can get away with .001"-.0015" of neck interference by tuning, then this, generally speaking, produces the best consistent loads with low SD/ES numbers. Smooth is key to precision, certain bullets do this too, others are erratic in start pressure by design.

Cheers.