Neck Turning

B

browndd1

Guest
I am trying to turn Lapua virgin brass (308 Win) down to .014 and can't seem to get it to 0 run out. A few cases have showed a low side of .0135 to .014 high side. The inside of the case necks look scored even after lubing with cutting oil and imperial die wax. I am wondering if the wobble has something to do with it. I am using a K&M neck turner with the power head adaptor and a cordless rechargeable screw driver.
 
So many questions.
How fast is that driver turning?
Are the necks getting hot?
Are you trying to turn to the finish dimension in one turn?
What is the source of the wobble of which you speak?
 
Id bet theyre running out in the driver head and after the violent neck expansion. Fire em then turn em again
 
I just turned 500 Lapua 308 Large primer brass and am in the middle of turning 300 small primer Lapua 308.
My turner is set for .014 also. The Large primer brass did not clean up completely @ .014 . I'd say an 90%
clean up . the low spots were at .0135 +- . The small primer brass all cleaned up at .014 .
I've seem this many times in the past.i've been neck turning brass for 35 years. My chamber is a 95 Palma
with a .342 neck. I didn't want to go any smaller. this 1/2 thousands difference is something that I will never see
on paper, or in score. Live with it ,it's not benchrest.
Ken
 
Ken Livengood said:
I just turned 500 Lapua 308 Large primer brass and am in the middle of turning 300 small primer Lapua 308.
My turner is set for .014 also. The Large primer brass did not clean up completely @ .014 . I'd say an 90%
clean up . the low spots were at .0135 +- . The small primer brass all cleaned up at .014 .
I've seem this many times in the past.i've been neck turning brass for 35 years. My chamber is a 95 Palma
with a .342 neck. I didn't want to go any smaller. this 1/2 thousands difference is something that I will never see
on paper, or in score. Live with it ,it's not benchrest.
Ken
Click to expand...

Just out of curiosity, what kind of tolerance are BR shooters looking for? I consider +-.0005" awfully good.
 
My limit is no more than is +-.0001 within a given set of cases. More often than not, I do better. Technique matters. With the right equipment, and good technique it would be impossible for me to turn cases as bad as +-.0005. I don't know how I would do it, assuming that the setting was cleaning up the cases all the way around, and from end to end.
 
Not too long ago I was using a K&M turning mandrel with the doughnut cutter on the end. It made the inside of the neck look like it was threaded. Are you using one of those?
 
Uthink Uknow said:
So many questions.
How fast is that driver turning?
Are the necks getting hot?
Are you trying to turn to the finish dimension in one turn?
What is the source of the wobble of which you speak?
Click to expand...
I don't think the little Black and Decker cordless screwdriver is turning too fast, I don't think the necks are getting hot and yes I am trying to turn to the finished dimension in one turn.
 
on my tight neck and fitted neck cartridges , I can turn them better than I can measure them.
I had one of those donut cutter mandrel things. I ground the donut cutter off so it don't hit.
Now it's a good carbide mandrel. This is the turner for 308. I also made a bigger handle for it
to act like a heat sink. the case lathe I use , I have set for 180 rpm. it's vari speed. Home made.
ken
 
Ken Livengood said:
on my tight neck and fitted neck cartridges , I can turn them better than I can measure them.
I had one of those donut cutter mandrel things. I ground the donut cutter off so it don't hit.
Now it's a good carbide mandrel. This is the turner for 308. I also made a bigger handle for it
to act like a heat sink. the case lathe I use , I have set for 180 rpm. it's vari speed. Home made.
ken
Click to expand...

Are these score marks inside going to affect accuracy. I am building a 308 Win with the goal of getting sub moa accuracy but don't have the gun yet. I have started making the ammo and have to talk to Dave Kiff on Monday to come up with a reamer for the barrel. I am thinking a .338 or .339 neck chamber, is this too tight?
 
I have a dehorned K&M carbide mandrel that had all of the sharp edges and corners rounded over with a coarse diamond lap, way back when I first figured out that for me, the reamer end had more minuses than pluses. Another thing, I let the turner wobble as much as it wants to, as well as what ever I am using to drive the case. I go to the shoulder with such a fast feed that I leave a lousy finish, and come back to the mouth very slowly, and then grasp the neck with a wad of 0000 and spin the case for about five seconds to improve the finish. The reason for the way that I feed the tool is so that the cutter will be pressing the neck to the mandrel all of the time that it is on the neck. This, combined with letting things self align (letting things wobble) means that the necks will be the same thickness as the gap between the cutter and mandrel. Trying to hold things straight, and having the cutter on the neck when it is not doing any cutting are counterproductive. Recently I have been playing with the top end PMA neck turner, with carbide everything. If you are shopping, they all turn necks, but this one is really nice. That is not to say that others are not as well.
 
I agree with you Boyd, on letting the turner float in your hand. Also the FIT of the mandrel is VERY important.
I use only Carbide mandrels. then I make the expander mandrel to the fit I want. The expander mandrel might
be different for new out of box brass to once fired and sized brass. of the same cartridge.
I have gathered a few turners over the years. Hart, K&M , old Sinclair and the NEW Sinclair, which I feel is the best
so far. I,ve HAD the pumpkin, and a few I can't remember the brand of. If I were to buy a new turner it would most likely
be the Century 21.
Another thing to keep in mind for consistent necks is the temperature of the turner and mandrel. I go at a pace that keeps the turner the same temp. and also pre heat the tool before starting. cold mandrel to warm mandrel makes a
difference. When measuring let the cases cool to room temp. Use a mic holder as if you hold the mic. it will warm up
and your readings will be different. Practice reading your mic. When measuring to a tenth of a thousands most cannot
do it reliably. When setting up, seat a bullet you will be using in a turned case and that will tell you the
true od so you can find your REAL clearance. Everybody likes tight. I ustocould. But clearance is your friend.
Too tight and you will get unexplained fliers . and a lot of them.
So far this winter I neck turned 1400 pcs of brass. most being 308, then 6.5-284 and a few for the Dasher. I still need to turn a few more Dasher and then 400 for the 7mm Shehane. Which isn't even built yet. I hope when I'm finished I will not need to turn brass for a long time.
This is just my way of turning necks . There are other ways, maybe better. But this is how I do it.

ken
 
I leave my turner in a bowl of icewater between pieces and before i start. Every case ive ever turned was done this way and ive never seen any variations since the cutter is the same temp for each case
 
Boyd Allen said:
My limit is no more than is +-.0001 within a given set of cases. More often than not, I do better. Technique matters. With the right equipment, and good technique it would be impossible for me to turn cases as bad as +-.0005. I don't know how I would do it, assuming that the setting was cleaning up the cases all the way around, and from end to end.
Click to expand...

Boyd, Would you please walk me through the tools and technique you use to arrive at the + or - 1/10,000 thousands of an inch disparity from perfection. The best I've ever done was 3 to 4/10,000 thousands. I'm willing to learn.
 
Sending PM...easier on phone. Well, I thought I was. You are not set up to get PMs, but I am. While we are getting this sorted out. What are you using to measure your necks with?
 
Last edited:
Boyd I try to keep my necks within 1/2 thou. And all my rounds come out no more that 2 thou. run out. all my junk doesn't read that fine. If I'm within 1/2 thou. I figured I've done my job, other than that its the brass. If I gall the inside of the necks I just take 0000 steel wool on a brush and polish the inside, I don't think you can get away from putting marks on the inside of the necks when you are turning.

joe Salt
 
You must log in or register to reply here.
Back
Top