I'm interested in the correct procedure to outside neck turn brass.
I.e. should the necks be turned before resizing or after firing?
What about new brass?
Printable View
I'm interested in the correct procedure to outside neck turn brass.
I.e. should the necks be turned before resizing or after firing?
What about new brass?
I've wondered about the "right way" to to trim the outside of necks & wondered if if might be beneficial for my 223WSSM . Little beast has ALWAYS had difficult bolt lift even with factory loads & no sign of excessive pressure....
make sure the mandrel is correct either way. the case neck should be centered so as to get an accurate even cut. turn to just before the neck shoulder junction. if you turn into the shoulder you may get a seperation
I like to turn after fire forming the case. mine are between .012 and .015 thousands.
If its a factory chamber I would only turn to about 75-80%. If you experience splits on the first couple firings you may have gone to far.
custom chambers are a different animal.
Apologies to the OP! I completely misunderstood the intent. I didn't realize that so many of you all are doing this. I am really enjoying learning about this process.
I have several tight necked rifles and wildcats that require neck turning.
The 243s are tight necked and the turning is required for proper fit.
These I size the cases full length when new then expand the necks over the mandrel to be used in the neck turner. This gives a snug fit on the mandrel when turning.With a sharpened and honed tool results are very good great finish and wall thickness to .0002. fit in the chamber is .001 or less
On the one wildcatt the neck and part of the shoulder ( .308 down to 264 ) thicken to where just neck turning would require 2 passes These get neck reamed in a die first then expanded and neck turned. Here with the added ream cleaning up the inside come out .0001 or less wall thickness run out.
Be sure if neck turning for a tight neck not to leave a doughnut at the shoulder neck junction.
Use a lube on the mandrel when expanding up and turning, saves on wear and eases the force when turning.
Neck turning for a factory or standard chamber consider setting the turner up to just clean up around 80% of the neck. Less work hardening, better fit.
Consider when neck turning going to a bushing sizing die and no expander button. This actually may be required when turning for a tight necked chamber as the standard die may not size down enough to grip the bullet. With the necks all the same the expander isnt needed just the proper dia bushing.
After turning cases need to be chamfered again also.
Normally the better cases only need ,001 or so to clean up decent. My 243s I cut more to get the fit most factory cases run around .270 loaded dia I turn to .2665. for the .267 neck.
When neck turning it is easier to work "on a side" ,012 wall thickness and set cutter to .0115 wall thickness this is /001 on dia. but this allows a shim between mandrel and cutter to set it very close.
While not need a light wipe of beeswax or light cutting oil on the neck will improve finish lubricating the cut.
Neck turning produces very fine sharp chips use appropriate safety gear. When the cutter is right there are a lot of 6 shaped razor sharp chips.
I use a K&M neck turner. You size the brass, then use an expander so the brass neck will fit closely on the pilot in the neck turning tool. Adjustment on the tool is graduated in .0002". I don't use a power tool to turn the brass to cut down on heat buildup and variations in case wall thickness. I tried the neck trimming style lathes and had had problems on tight neck chambers.
Country Gent has given very good advice. I have been shooting tight neck rifles for over 20 years, and turning necks are common place. Getting the proper fit with the mandrel is key. I use the K&M system, they have their own expanding mandrel that in turn fits their turning mandrel. I like using their carbide turning mandrels, super smooth.
Cleaning up the neck diameter is one thing, but if you are turning to fit a tight neck chamber, you have to hit the clearance just right. It may require two steps, depending on how much needs to be removed. Done get in a hurry, the deeper the cut, the more heat.the mandrel heats up. Take your time.
Another K&M user, what others have posted about using them is spot on.
The only thing different that I do is I trim the cases after full length sizing them. The mandrel and cutter clean everything up while they're cutting on the necks.
When I started into neck turning I couldnt afford the KM or sinclairs, but I had a full machine shop and lunch breaks available I made my own tooling. Several hand units one with a lathe type bed that did good but was slow. the last were more like a fly cutter. the mandrel was long enough to allow chucking it in the drill press. the fixed stop maintained good accuracy. I could now turn at 600 rpm. much faster and easier on the wrists. I made a simple die body to hold the mandrels when expanding, mandrels were ground from 1/2" drill blanks.the bodies from SS. Cutters were ground from 1/4" cemented carbide lathe tools then hand honed. An neck wall thickness gauge was made with a .0001 mititoyo indicator.
Am I interpreting this correctly? If my rifle has a factory chamber, the depth of the cutter would be set such that about 80% of the neck circumference is affected, leaving 20% untouched by the cutter?Quote:
Originally Posted by country gent
This is an area in which I have no experience and I’m trying to envision the process.
Thank you for the education!
Yes you only want to remove enough to true up a factory case with a factory chamber as neck expansion will be more as will sizing work hardening the brass more. 80% clean up in a factory chamber will normally only leave about .0005 neck wall run out but save a lot of expansion. remeber to clean up that last .005 is .001 on dia as .0005 will be taken on both sides.
Here is the difference a standard 243 is around .272-.273 loaded neck dia to fit the factory chamber. A tight neck chamber is around .268 so that a factory round wont fit and be fired in a no room for expansion to release the bullet condition. This really jumps pressures. The difference between the 2 is only .005 or .0025 on a side but its more expansion and works the brass more. As I said above on my 243s with tight necks they are .268 I turn so the loaded round dia is .267 - .2675 leaving .001 - .0005 for expansion at the tightest. On lapua brass the spring back will allow the bullet to just slide in a fired case
If your sizing down brass say 308 to 243 and the necks thicken then you have the material to turn a fitted neck in the factory chamber and maintain dia. Allowing off the shelf sizing dies to still work. In mine I had to go to bushing dies to get the tight neck tension back.
Neck turning is a specialized technique for the ut most in accuracy in specialized guns. Or a means off reducing loaded neck dia when reforming brass.
In a factory chamber with standard cases the gains are small unless you neck down a bigger case and turn to the fitted dia.
Modern brass is much better than even 15 years ago. Wall thickness is much better. Also those cases with .003 - .004 run out in the neck wall when sectioned will show .010-.015 at the head body and this cant be fixed. One of the benefits of the lathe turned brass becoming available now.
Thank you for the clarification!