Neck Expander before Turning

[cooperve]

Could anyone give the pro/con of Sinclair vs. K&M expander systems? I am thinking of a purchase, but I have no experience with either. They are priced about the same. I'm looking at .17, .22, .24 and .30 expander sizes.
Thanks.

[SmokinJoe]

I think the current Sinclair or 21st Century version compares well with the K&M. You may find it more important to investigate which mandrels work best with your turner mandrels.

[philip]

I have the 21st century neck tool and am happy with it...

There is another new (to me) neck turner out there called PMA tool...

They look nice too,but i have no first hand experience with them.

Phil.

[Varmit Dan]

Re your specific request to compare expander systems.
I prefer the K&M Expandiron tool over the Sinclair expander tool because the K&M mandrel is not shrouded and I can always see the case mouth.
I don't always use the Expandiron's adjustable case bottom stop, but it can be useful.

Another aspect already commented upon would be mandrel diameters. I have used both K&M and Sinclair turning systems, mostly purchased 10-12 years ago so my comparisons may not be current. Expanding mandrels are size matched to the companion turning mandrel to provide some neck tension on the turning mandrel, but I THINK my K&M sets are 0.001' smaller than my Sinclair sets which provides a bit more neck tension. Neck turners are oriented toward benchrest practice which is deliberately LOW neck tension re use of Wilson type seating dies by hand or in arbor presses. A bit more neck tension than that does not hurt when fire form rounds are being used for prairie rat work. As suggested in a previous post, you may be able to optimize neck tension after turning to some degree by your brand choice, or possibly you could request custom mandrel diameters.


You did not ask for turning tool comparison, but I prefer the K&M cutter adjusting system, smaller size, and shorter cutter surface which make cutter angle less important for some cases. I found the K&M cutter to be better suited to a broader range of neck/shoulder angles. Since first writing this I went to the Sinclair website. They have improved their tool's adjustability over what I own but the cutter looks similar as far as I can tell from the picture.

Before reading a previous post I was not aware of the 21st Century or PMA products and went to their websites. I like the 21st Century cutter angle options re dreaded donut brass removal. I did not spot anything special about their expander offerings.

My preferred lube for neck turning is ProBlend engine assembly lube which Sinclair once offered. I have not looked up what they offer these days. I have also used a lube that pitchmen pitch at car events, where they yak yak yak and stall a bearing with some standard lube, but the ProBlend is better.

[cooperve]

Varmint Dan
I was leaning toward the K&M just for the reason you suggested - easy to see what your doing. They also have a new extension that will bring the work above the press and still see the bullet enter the expander.
I have for many years only neck turned to round the necks. I only turned until about 90% of the neck was clean. Shouldn't get into trouble this way. I've been a varmint shooter, but getting interested in "casual" bench rest. I have been using the Forster neck turner add on. I know the expander is the correct first step and it will make it easier to neck turn.
I may upgrade from the Forster after I determine how accurate or in-accurate the Forster is. A new turner would probably be the next step.
I will hold off to see if anyone else has additional suggestions. I'll probably hear suggestions about the Forster.

[Varmit Dan]

Your post has pulled me into updating my info on available neck turn tools. Thanks.

1. I was not aware of the updated K&M expander mandrel holder that allows you to see the neck passing over the mandrel while above the press. The newer K&M holders looks to me like my dated Sinclair holders with a cutaway slot. A viewing line ABOVE a press certainly seems like a better neck strain ergonomic. I expect to purchase a couple.

2. Re using someone other mfr's expander mandrel products with a Forster case trim attachment neck turner.
From looking at the Forster website instructions it seems to me that the Forster turning pilot is likely sized for necks sized in FL dies. If that is the case, I would expect that the Forster pilot might be mils smaller than K&M or Sinclair expander mandrels, meaning a relatively sloppy hold for cutting if you expand with K&M or Sinclair mandrels. If you have a good micrometer, preferrably one that can measure tenths, you will be able to sort this out. Or perhaps someone who has sorted this out already can jump in.
One of the design points of my now dated K&M or Sinclair mandrel sets was to provide a snug but not high friction fit over the turning mandrel. That approach seems worthwhile to me. I am not at home else I could measure what I have, but I believe that my expander mandrels were 0.001" smaller than the companion turn mandrels, i.e. a planned 0.001" neck tension, and the K&M set were each 0.001" smaller dia than the corresponding Sinclair parts.

3. Were you cutting 90% of necks in the past out of concern for cutting into the neck/shoulder area?
When I was first getting into this, and first heard of the "dreaded donut" brass ring that can form in the neck/shoulder junction, I failed to find discussion, even from my benchrest gunsmiths and shooters I knew to ask, that gave me final confidence for setting the amount of cut into the neck/shoulder junction. For one of the first cases I worked with, using a Sinclair neck turner, the first type I owned, to remove any neck/shoulder junction brass I was cutting a shine well down the shoulder. This alarmed me until I diagrammed the neck and cutter in large scale and could see for myself that what I was doing was just fine. Still, I moved to the K&M cutter over the Sinclair cutter for most cases.
After K&M came out with turn mandrels with end cutter, i.e. donut cutter, I have only purchased those type of mandrels.

4. re moving to a new cutter.
I am in favor of hand held cutters such as K&M over case trimmer attachments. For volume varminting case prep, my main application, the case prep rate is probably better. Machinist shooters have told me that hand held cutters can follow the case wobble inherent with hand held powered turning devices such as drills or screwdrivers.

5. hand turning versus powered drive turning
For cleanup turning a hand tool has been fine for me. I switch back and forth between K&M and Sinclair holders to try to avoid cramps. For one step tight neck turning where you are removing more brass I prefer some kind of power drive. I have used large, slow RPM electric drills, 3/8" class drills, and a variety of cordless drills and screwdrivers, whatever was charged up at the moment. The Sinclair holder is my favorite because of its larger diameter although the K&M side flats have their benefit. I try to turn as slow as the tool will smoothly drive the cutter to minimize heat buildup which, as K&M literature warns, can reduce precision and repeatability. A benchrest shooting friend dips his turner in ice water between cuts but I have never done this.

[SmokinJoe]

Just saw the new 21st Century turning setup, be sure to look at it.

[vmthtr in Green Bay]

Originally Posted by cooperve

Varmint Dan
I was leaning toward the K&M just for the reason you suggested - easy to see what your doing. They also have a new extension that will bring the work above the press and still see the bullet enter the expander.
I have for many years only neck turned to round the necks. I only turned until about 90% of the neck was clean. Shouldn't get into trouble this way. I've been a varmint shooter, but getting interested in "casual" bench rest. I have been using the Forster neck turner add on. I know the expander is the correct first step and it will make it easier to neck turn.
I may upgrade from the Forster after I determine how accurate or in-accurate the Forster is. A new turner would probably be the next step.
I will hold off to see if anyone else has additional suggestions. I'll probably hear suggestions about the Forster.

Don't waste your money on the Forester. It does not make a nice smooth turn on the neck. Get the K&M.

[ab_bentley]

K&M, 21C, HART, All top notch tools. Forster isn't in there. ADam