You can be lucky sometimes but secondhand stuff is always risky , especially if you can't inspect it first . I have been caught a few times by evil bay .
I use Sinclair but K&M works fine also .
You may be interested in my partial neck sizng technique when neck turning for a factory chamber . Maybe not , but I will post it anyway for interest.
Neck Turning.
Neck turning is a process of machining the external neck walls of a cartridge case to an even thickness and an accurate diameter.
This is achieved by the use of a neck turner, of which there are numerous brands.
The reason this is desirable is to achieve better concentricity and minimum clearance in seating the case in the chamber as in tight neck chambers.
To gain better neck seating tension and concentricity of the projectile, due mainly to the fact that the seating tension is more equal around the diameter of the case neck.
Even neck tension on the projectile also helps the seating die do a straighter job.
The even thickness necks allow more precise neck tensions from case to case, and assist the neck sizing operation and bullet seating operation to do a straighter job.
When turning for a factory chamber it is not necessary or desirable at the first turning to achieve 100% cleanup of the case necks as long as most of the neck is turned say about 75 % of the circumference area .
When turning for the first time to get a case to fit a tight neck chamber it is best to reduce the necks to the correct diameter in several finer stages of cut. Two separate cuts will work ok.
This results in a better degree of case neck diameter uniformity across the batch of cases. Tight neck cases should have a neck clearance in the chamber of not less than .001 of an inch all around the circumference, that is .002 clearance across the diameter with the projectile seated , unless you are an experienced bench rest shooter and know enough to do otherwise.
The trick to getting good results is the inside fit of the case neck onto the mandrel of the neck turner.
It must fit perfectly with no sideways clearance or slap, but be able to turn easily and not jamb as the neck heats up.
This is easier said than done. Inside neck reaming or polishing before sizing to the mandrel will help in this regard and there must be no donut inside the neck.
A donut is a circular ridge inside the case neck at the junction of the neck and the shoulder.
Lubrication of the turner mandrel is absolutely necessary, to stop heat lockup. Use gun oil with a small amount of moly powder mixed in on the mandrel. Sometimes small amounts of brass will build up on the mandrel and cause the case to get sticky. If this happens polish the mandrel with fine steel wool by hand .
Don't use harsh abrasives as you do not want to reduce the diameter of the mandrel. I use a Sinclair neck expander die to expand the necks to the correct size , if they are too big to begin with , neck size them down with a standard neck die without the decapping rod then neck expand them up to the turner mandrel size.
The mandrel in this die has been polished down a bit at a time so it is just a fraction larger than the mandrel in the neck turner.
Remember case necks spring back smaller after coming off the expander mandrel.
When the cases come out of the expander die they should be a neat fit on the turner mandrel, trial and error will be required.
Neck Turning for a Standard Chamber
I have read many times the statement that neck turning is a waste of time for standard factory chambers.
Well it depends on how you do it .
First you must study the article on neck turning and learn how to turn an accurate case neck.
When you have mastered that you can apply the sizing system outlined below.
There is no denying that turning a case neck for a factory chamber will increase the clearance between the case neck and the wall of the chamber, but you can retrieve this clearance for a section of the neck to a tighter fit than before turning .
With partial neck sizing and body die sizing .
The idea is that you leave a portion of the neck , about one third of the length from the shoulder , unsized at all times.
To achieve this a bushing type neck sizing die or a Lee Collet neck sizing die is used to size the neck only . To shorten the length of sizing in a Lee collet die place a machined washer of correct thickness over the case and between the collet skirt and the shell holder .
This section of neck never gets sized that is why it must be kept short .
If it is too long it can make chambering difficult and there will not be enough sized section to hold the projectile concentric and secure especially in short neck designs like 243 W .
A body die is used to size the remainder of the case when necessary and it doesn't touch any of the neck .
This way you gain some of the benefits of neck turning , without the disadvantage of excessive neck clearance in the chamber.
This is a technique for a bolt action rifle that has already shown to be accurate and you want to improve it .
It is definitely a waste of time employing this idea in a rifle that doesn't shoot well enough to see any small improvement in the groups.
Other methods such as pillar bedding , hand load development , quality projectiles etc, would be more likely to improve the bad shooting rifle .
So work on everything else and when you run out of things to improve , it may be the icing on the cake .
There is no one system of anything that suits every rifle , the secret to performance is experimentation.
Some rifles brake all the rules such as shooting better with Full length sized cases than Fire formed cases.
Things like this can usually be traced back to some inaccuracy in the original manufacture e.g. crooked chambering job.
It's your job to figure out what works and what don't.
This article is designed to help you think about ideas you may not have come across before.
I have been using this system in some of my rifles for many years and find it improves accuracy .
Written by John Valentine 25 / 10 / 07. Copyright
