Neck Turning Issues

[Jud96]

I recently began neck turning for a 0.270NK 6PPC and have been struggling. I have necked turned in the past for my .243 varmint rifle and that went smooth, turning off about .002 from that brass. I’m using a K&M neck turning kit, with their mandrels, turning tool, expander die, case holder, etc. I have 2 K&M turning tools, I have one set to .013 and the other .0118-.0119 for my finish pass. The problem I’m having is, when the brass first makes contact with the cutter, it grabs and jerks the case loose from the case holder, or the brass just sits right at the start of the cutter and I have to push hard then the brass gets sucked in by the cutter. I tried turning like 10 cases and half of them worked fine and the other 5 the necks grew longer and stretched. It’s like the brass is being squeezed and not cut on some pieces. Also, after the first case got screwed up, on the next case the cutter barely skimmed. So I readjusted the tool and it’s still giving me issues. I had this happen once before on some 6.5 Creedmoor brass. I don’t know what I’m doing wrong, because this shouldn’t be this difficult. One of the neck turners is brand new, the other is used, but worked fine the last time I neck turned .243 brass. I don’t want to keep ruining Lapua 220 brass considering how hard it is to get. Any input is helpful and appreciated, thank you!

 

[mikecr]

How thick are the new necks (that give you trouble)?

 

[Jud96]

.0145-.015 on all the virgin brass I’m turning

 

[piie]

Try to take off less with your first pass?

 

[Jud96]

First pass is only .0015-.002. I know many guys who turn .003-.004 off in one pass for 0.268 neck chambers.

 

[FeMan]

Have you tried changing the rpm you are turning?

 

[paperpuncher]

I wonder if the cutters edge is above the centerline on the mandrel. Perhaps disassemble and look for a burr or dirt ect

 

[Jud96]

Have you tried changing the rpm you are turning?

No, I was running it kind of slow. I’ll try speeding it up

 

[williepete]

Use a lot of lube on the neck cutter and the mandrell

 

[LHSmith]

Since brass is free-cutting- lubing the neck OD should not be necessary. Lubing the mandrel is. Carbide mandrels are well worth the money. What kind of case holder? Sounds like you can't get it to hold tight enough.

 

[rwj]

Have you inspected the tool cutting edge for wear/damage? They are a consumable item in the process.

 

[JEFFPPC]

I turn by hand but when I have that problem its from trying to cut too deep.

 

[drop_point]

Lube the mandrel, lube the necks inside and out, and start very low torque on the drill as you begin your cut. I don’t start the drill on the brass, but give it a really mild “running start”. I try to take off 0.001” at a time.

 

[LCazador]

If it too tight on the mandrel it may cause it to hang up on the cutter. You may have to go to a slightly larger mandrel. You may also want to check the degree of angle on your cutter vx. your brass. I don't like taking more than .001" at a time

 

[ScottVA]

Lube well and do a heavy chamfer on the outside of the neck to facilitate the feed onto the neck if you have not done this, already.

 

[std7mag]

.0145-.015 on all the virgin brass I’m turning

Virgin brass = soft.

If the cutter is dull, not centerlined, speed too slow, cut too deep will all give you the symptoms you described.

 

[Alex Wheeler]

Cutters too sharp. You want tool push off and snug mandrel fit with neck turning. The directions that come with the tools are not the best. Dull it up slightly. Fit it so you cant push it on without it under power. Trial and error. You can get it to where you cant find a tenth.

 

[ronemus]

Be sure to get a carbide cutter - tool steel dulls, which also changes the depth of cut. Carbide for cutter and mandrels is the way to go.

 

[Jud96]

Quick update. I switched to using FP-10 oil on the turning mandrel and inside and outside the case necks. I also chamfered the outside of the necks. I stopped using both turners and stuck with the new one setup to take one pass. I did 6 cases in a row this morning with no issues and all were right on size. Thank you all for the help!

 

[AlNyhus]

Glad you found a work around. Chamfering the case necks can really help with the initial 'grab' of the cutter. FP-10 is a good lube.