Neck turning pilots

[Caliper_Mi]

So, I'm making 260 Rem brass from .308. I've found that some sort of neck turning will be needed since just resizing and loading rounds gives me a neck diameter of .297-.299 and they fail the plonk test. Heck, they'll almost stick in the chamber... Resized 7mm-08 and .243 chambers just fine, so the neck thickness definitely is the issue but I only have a handfull of brass for those vs thousands of .308 brass.

I've bought a K&M neck turning tool (beautiful tool, BTW) but their pilot is naturally larger than the ID of the neck of my resized brass. It seems silly to me to use an expander mandrel to expand my freshly resized brass to turn it, then resize it down again. Is there any reason that an expander mandrel must be used that would hurt the brass if it wasn't? Would I by nuts to polish the neck turner pilot down to match my resized brass and save two steps in forming the brass?

 

[rcmodel]

No.
Thats what I would do.

I have made several case trimmer pilots and turned down others.

rc

 

[gamestalker]

Awesome, this provides some insight for my neck turning endeavor as well.

GS

 

[Walkalong]

Expander die body:

http://www.sinclairintl.com/reloadi...ir-generation-ii-expander-dies-prod38807.aspx

Mandrels:

http://www.sinclairintl.com/reloading-equipment/case-preparation/neck-turning/index.htm

I have an old Gen 1 die body and some mandrels.

 

[Clint M]

You want to use an expanding mandrel to set the inside diameter of the case to match the neck turning mandrel if you want accurate results, otherwise different brass thickness which does vary by manufacture etc you would have neck run out all over the place.

The expander mandrel also irons out any wrinkles in the neck if used with bushing type dies and pushes the imperfections to the outside of the neck where you are turning off.

Hope the above makes sense to you, a good neck turning tool will require you to expand the inside neck diameter to a nominal size, K&M will match the expander, and mandrel to what you need, so buy from the company you purchased neck turner from, if making your own it's trial and error make one and turn/polish down until desired results. I wouldn't mind having some small primer 260 brass, but I have a huge stash of 260 brass I purchased years, if you need a few cases to know where factory measurements are let me know, or I can post some measurements for you...problem with measurements is everyone measures with different hands, ad tools, but for factory and government type work we get buy ok.

 

[farmerboy78]

+1 with clint, it makes everything uniform inside and out...

 

[Caliper_Mi]

I agree that I'd want a consistent neck ID to begin the turning, but the expander of my FL resizing die should do that just as well as an expander mandrel. Variance in thickness of the neck of the parent brass would cause some variation in the resized brass, but wouldn't the same happen with an expander mandrel?

I guess it boils down to, is there any difference between having an expander that takes the neck to .263 for use with a .263 pilot, and a FL sizing die that takes the neck to .259 and using a .259 pilot? As long as the pilot matches the ID of the neck, does the exact size make a difference?

 

[Clint M]

The exact size does make a difference, and I wouldn't be surprised if K&M is not working in the .0000(+/-) area for both pilot, and mandrel. Yes your full length die expander does pretty much the same thing, but you have brass spring back, and die manufactures make the expanders to different sizes using different materials that will just add up to a bunch of costly custom pilots. The more custom it becomes the more costly, K&M can streamline by making a standard diameter pilot for use after using a standard diameter expanding mandrel for that pilot after testing for brass spring back, toughness, etc etc. It's much cheaper for K&M and you in the end, and with better results and most important happy customers.

You can order a custom pilot possible to fit your neck turner, keep in mind you may have to order several size pilots as your full length die is sizing the case neck diameter down a considerable amount, so the brass toughness, springback etc can all accumulate to drastic measurement differences in neck turning. By full length sizing in one operation doing the majority of sizing, then expanding in another operation(with K&M expander die/mandrel) you have much better control over end results. Turning brass is a pain, and it's the tools, cost, tools, time, tools, test/retest,tools that make it such a pain. However with the setup you have using the correct expander mandrel I have no doubt if used correctly you will have nice useable brass for your 260.

I have sized down 308 to 260 before and didn't need neck turning on a Remington factory chamber, however it's a good idea to check as it is increasing neck thickness. I used to have a small simple chart of decreasing neck diameter=increase in neck thickness, wasn't exact but darn close. What brass are you using, and what kind of gun etc ?

Edit to add this+ I see your finished full length sized ID is .259. K&M pilot is .263 that is very little to expand, and you so much more control over this amount than what your full length die is sizing down. Try sizing a piece of brass down in you FL die with expander removed, please post results as others look to be interested as well. It should make much more sense to answer why K&M uses a standard size pilot with use after using a standard size expanding mandrel.

 

[ironworkerwill]

I shoot a match chamber in 7mm-08. If I size .308 brass to 7-08 it will need to be neck turned else a loaded round will stick in the chamber.

I have noticed if I size from a larger cal to a smaller cal neck expanding will be needed. When using a standard FL die the neck builds up and the expander cannot expand enough to fit on the .282 mandrel.

If I use 7-08 brass or smaller the necks will not NEED to be expanded but will be snug and will NOT fit on the mandrel while dry. If a small amount of case lube is used the case will slide up the mandrel. Now if i was HAND turning, I'd probably expand all of the necks to get the last .001" to reduce friction. Since my first turning session I have always used a POWER ADAPTER. Hand turning got very old, very fast.

 

[JimKirk]

So if ... you expand the neck using a stand alone expander(matching the neck to the turner pilot) ... or you expand using a sizer die (matching your turner pilot to the expander size) .... how is one better than the other?

 

[Clint M]

He has a .263 pilot, he needs to expand the necks to .263, one way of expanding is not going to be much different than another full length or mandrel, what is important here is the amount of expanding, and final diameter. You have so much more control when expanding .004" (in the OP case) than a FL die sizing a case down .100" dragging a .262" expander ball back thru the neck expanding the neck .100" +thickness of neck x2= ??+brass spring back+ differences in case neck thickness= lots of difference in final ID using a FL die

A full length die from different manufactures will have different size expander balls, as well as different brass manufactures, state of brass etc will make a difference on ID after expanding. You can either order several custom pilots, or for less hassle, and headache use a expander mandrel to expand the last few thousandths to desired ID (pilot) it's not as simple as just getting a .259 pilot, and a .259 full length sizing die expander ball.

Easiest way I can explain it is take several pieces of brass different manufactures, some new, some fired size FL size them and see what you get for ID.

By the way make sure you trim your brass all to a desired length before neck turning.

 

[Clint M]

Direct from K&M, you can go to the site for more information

Virgin/competition Brass isn't quite ready to Neck Turn when you buy it. And the commercial die manufacturers have no set standards for the Expander button in their dies.
Large variations from manufacturing to manufacturing and even within a given manufacturing makes it necessary to properly size the inside diameter before turning.
Don't be fooled by slick talk. The turning pilot cannot be used to correctly expand the case neck because of the elasticity of the brass; it will spring" back and be too tight for proper Neck Turning.
The 7/8-14 Threaded Adapter fits your Normal Reloading press and the interchangeable Mandrels are sized to be the perfect companion to the K & M MICROADJUSTABLE Neck Turner. The EXPAND MANDRELS will iron out (smooth) and slightly expand the case neck so the brass will spring back to the correct size needed to neck Turn your Pet Brass.

This tool can also be used to expand up to a larger caliber; great for the Wildcatters.
To remove the DREADED DOUGH-NUT, adjust the bottom screw to stop the NECK EXPANSION just short of the DOUGH-NUT. Then the neck is the correct size for the K & M FLUTED CARBIDE neck turner pilot to remove said Dough-Nut.

Mandrels are available in cal. .17, .19, .20, .22, 6mm, .25, 6.5mm, .270, 7mm, .30, and .338. Each Mandrel has an adjustment screw to bottom-out in the Brass before the case mouth can hit the mandrel's shoulder.

 

[JimKirk]

I am not saying to use the pilot as an expander ... what I am saying is if the diameters match correctly that it makes zero difference ! Does not brass thickness and spring back effect the diameter when using a expanding mandrel?

 

[Walkalong]

As long as the expander of your choice matches up with your brass and neck turning manual, your good. The expander has to be slightly larger than the neck turning mandrel. .001 over is a good place to start.

I used to ream the inside on a Wilson trimmer, then use a Sinclair expander to slightly increase it to be a tight slip fit on the neck turning mandrel. That was for .220 Russian formed to 6PPC.

Like neck bushings, you'll never end up with just one expander.

 

[JimKirk]

The expander has to be slightly larger than the neck turning mandrel. .001 over is a good place to start.

Or the turning mandrel has to be .001" smaller than the expander ... right? Same difference?

 

[Walkalong]

Yep. The one we expand the neck with has to be slightly larger than the one we use to turn the neck on. We want a tight zero play fit for the neck turning mandrel but it has to rotate reasonably freely. I described that as "a tight slip fit".

 

[Clint M]

As long as you can expand to the ID diameter that the manufacture (K&M here) specifies for their pilot it really does not matter brand etc, but you do not have enough control using a full length die. Check the rest of K&M info not just expanding using the pilot info.

Exceptions to this rule may be using custom chamber gun, custom FL dies, and or custom bushing dies, even still most will choose the expander mandrel route in order to have control of sizing a small amount (less than .010") to get a repeatable final ID to use for pilot versus a full length die sizing the neck .120" or possibly more, maybe less. I have to load some 223 rounds I will see how much the neck is sized down (remove expander assembly) and report back...

I'm having a really hard time explaining this information for some reason. I'm trying my best to give good, reliable, dependable information in order to help those who are interested in turning necks as it's a process that can be easy with the correct tools, or really hard with varying results that degrade accuracy, ruin brass, costly tools of no use or inferior use. Maybe some others with more experience, with later more up to date equipment can chime in as I have a Clausing 10" lathe I now use for any neck turning projects. With the pumpkin type neck turner I have used, a Forester type, and my lathe (best overall by far) I can not produce results an better than Lapua sells as factory, and very very little better than Remington, Winchester or any other decent brass sells as factory accuracy wise, nor overall concentric when taking into account if the neck is thicker on one side, so will the wall of the case be thicker down to the web. Maybe the OP can chime in as well as he has purchased tools available up to date etc, and tell us the route that he ended up using along with results.

 

[Caliper_Mi]

He has a .263 pilot, he needs to expand the necks to .263, one way of expanding is not going to be much different than another full length or mandrel, what is important here is the amount of expanding, and final diameter. You have so much more control when expanding .004" (in the OP case) than a FL die sizing a case down .100" dragging a .262" expander ball back thru the neck expanding the neck .100" +thickness of neck x2= ??+brass spring back+ differences in case neck thickness= lots of difference in final ID using a FL die

A full length die from different manufactures will have different size expander balls, as well as different brass manufactures, state of brass etc will make a difference on ID after expanding. You can either order several custom pilots, or for less hassle, and headache use a expander mandrel to expand the last few thousandths to desired ID (pilot) it's not as simple as just getting a .259 pilot, and a .259 full length sizing die expander ball.

Easiest way I can explain it is take several pieces of brass different manufactures, some new, some fired size FL size them and see what you get for ID.

By the way make sure you trim your brass all to a desired length before neck turning.

I agree that different dies and brass will result in different neck ID, so I understand why the tool manufacturers make the expander since most people won't want to mess with fitting the pilot to their FL die. Of course, the same variation between headstamps should affect the expander mandrel just as it does the FL die since springback will be present whenever changing the neck size.

FL sized brass from PPU, CBC and LC13 all measure .260-.261 ID after resizing in my RCBS die (only 260 dies I have) This is all once fired .308 that will be turned into 260 and once the excess neck material is removed I don't see the need to neck turn again. Don't have any new brass since I've only bought loaded or once fired brass.

OD of the sized brass varies by manufacturer from .295 to .297 and thus loaded rounds are at or over SAAMI max spec for the brass. It all fails the plonk test in the Shilen barrel I'll be using and chambers very tightly in the factory Savage barrel on the rifle currently. There are shiny spots left on the neck after chambering brass with a bullet in it.

I've got a question then. I'm not seeing the magic of the expander mandrel except that it is matched to the pilot from the same brand. Say you resized your brass and the ID of that sized brass matched the OD (or just very slightly larger) of the turner tool pilot. Would you still run the expander mandrel through the brass? Why or why not?

 

[ironworkerwill]

Say you resized your brass and the ID of that sized brass matched the OD (or just very slightly larger) of the turner tool pilot. Would you still run the expander mandrel through the brass? Why or why not?

If you had an ID greater than your turning mandrel try sizing without the expander installed in the die. Then used the expander for the corresponding turner mandrel.

I personally do not use the expander if the tolerance is close enough. I know the idea is to move the imperfections to the outside of the case, however, I get good results without having to go through an additional step.

A little snug on the turning mandrel is a good thing, loose is not good at all.