I have taken delivery of a K+M neck turner and was wondering what is the best or even correct method of using the tool and what difference has it made to your shooting. The instruction are vague as to how much brass you can cut away etc .
Thanks in advance, Bob

bobb, there are no precise gudelines that I'm aware of. Different cases have various wall thicknesses to start with, the .22 Hornet is generally less than .010", larger cases up in the range of .015" or more. I've heard the new short fat Remmy and Winchester cases are thicker, but don't know specifics.

The primary benefit to neck turning IMO is consistancy in neck tension and/or having the ability to tailor neck dimension for guns having fitted chambers. In the first case it is not necessary to completely clean up a case neck and I rarely do so, leaving them with some old surface and some new shiny bright. After another firing I take another look and repeat if warranted. In the second case, it's simple math, you need a LOADED case neck approximately .002" smaller that the chamber neck diameter to ensure adequate release of the bullet upon firing. Custom guns with tight chambers usually have the neck diameter stamped on the barrel or otherwise communicated by the gunsmith. Firing cartridges without unturned necks in such guns can be dangerous.

In either case, excessive turning will lead to very low neck tension and that leads to poor accuracy, especially when slow burning powders are use. Proceed thoughtfully, you'll get it figured out soon enough. If you don't have one already, find a proper mic for measuring neck wall thickness, the standard dial caliper ain't it. RCBS make a tool called the Casemaster which measures neck wall thicknes as well as concentricity of case neck and bullet after it's loaded. Useful item to have around.

Bobb d,

Welcome to the forum.

Case necks should only be turned down if you have a tight necked chamber.

First you have to know your chamber neck dimensions, then you have to determine the necks of the cases you are going to use. From these two measurements, you can calculate how much brass you have to take off the necks.

Here is an example, for the 6mm PPC cartridge.

Chamber neck is 0.262"
Bullet diameter is 0.243
A dummy round, no primer or powder, with bullet seated in a new case, measures 0.265"

As you can see from the above, if you do not turn the case necks down, you won't be able to chamber a round.

So, next we have to determine how much brass we have to take. Personally, I like to have a clearance of about 0.005 between the loaded neck and the chamber.

This means we have to make sure the loaded round measures 0.261

We deduct 0.261 from 0.265 and get a difference of 0.004.

This means you have to set up your neck turner to take off 0.002.

I hope this explanation helps you in your set up.

shooting a 243win. I take fired cases and full length size(standard RCBS FL DIE) them before turning.I then turn to the shoulder taking off metal all around the case. If you dont full length resize first u cant get a correct cut to the sholder.After the next firing the brass is sized in a redding type s full length sizing bushing die. The bushing die is adjusted to size only part of the neck to hold the bullet. The unsided part of the neck expands to the chamber, centering the round in the standard factory chamber. If you have a tight neck bench rest chamber, do as others have said.Redding Bushing die

You did say what type of shooting you do, but
If your a paper puncher it may make a difference. If your a hunter, probably not.

The idea is good and sound, but it's one of many very small extra steps that you can pay attention to for accuracy, like; distance to the lands, if you've got the time.

I use the K&M on rem brand 300 wby brass. First of all I hope you have a mandrel that will "oversize"the case mouth so that it fits on the "cutter" mandrel. I use Imperial sizing wax on the mandrel as a lube and I use a drill mounted chuck to hold the brass while I spin it onto the mandrel and cut it. I try to get a fairly clean cut but sometimes leave just a little on the necks unturned.

Alot of people feel the way Saeed does that neck turning is for "fitting" the shell to the chamber but I think it has more benefits. When I buy the rem brass it shows up almost in "pure junk" form. The cases and especially the neck area are very dented and beat up. If I don't neck turn this brass I probably won't see loaded runnout on this brass much under .003". But, if I true up the case mouths and neck turn the brass I get what I feel is a very good effect. Namely all sized brass (after one firing) comes out at .001" and under. And because the necks are a little thinner I think they get "worked less" during the sizing process. The net effect is when I seat bullets they all seat the same with exactly they same feel and about 90% off this rem brass will come out loaded at .001" and under. Does it make a big difference in a long throated weatherby mark V????? I can't say for sure but the gun I load for has a 10x scope and it regularily puts 180 barnes xbts into a nice round 3" group at 300 yds. I'm a fair shooter but no expert by any means and fine haired 20x scope over a thick haired 10x hunting scope with "higher definition" targets might yield even better groups. Bottom line is it takes me about 1.5 hours to neck turn 100 brass and that much brass will last me years. I believe the process has merit and is worth it even in a normal hunting rifle.

Let me know if you have more questions. I'll be glad to try and relate my experience with the tool. Good luck Don

Saeed,

You explain things well. Why don't you tell him about "donuts" and how to remove them if he wants to.

I have developed a different approach to neck turning... I don't. I decide what brass I am going to use for a cartridge, make up many dummy rounds and take measurements. I then change the specifications on the chamber reamer to cut a neck that will have the minimal appropriate dimension. I match the chamber to the brass. Of course this requires buying brass that has reasonably consistent dimensions. I have had great success so far with Lapua brass. I am not a benchrest shooter but do like to have accurate ammo for varmint shooting.

I only turn necks on my 6x45 (outside turn them) as they will not chamber if I do not, and I have a 0 tolerence chamber with that rifle, in fact I can reload it without resizing most of the time...

I would never turn the necks on a big game rifle, not brass is that much out of spec, and if it was I'd toss it...