30BR neck turns very heavy

V

VT52

Guest
Hi,

I have an issue with turning 30BR brass for some reason, which I have not had with any other caliber I've turned.

I use 6BR lapua brass and expand over a redding 6mm-to-.30 taper button with imperial wax. The case goes into a mini lathe and I hold the neckturner (sinclair's) by hand.

Before I get half way, the brass "bites" and it becomes almost impossible to hold the turner in place, it's that heavy. I've tried pushing through a sinclair .30 expander after the redding button, but it does not help much. So far I've tried with two sets of expanders/turner mandrel to see if one isn't just off by a thou.

I'm turning .22, 6mm and 6.5 this way and they all go smoothly, although none of these are stretched up from 6mm to .30.

Anyone have suggestions what can be done to solve this? Make an expander that is 0.001" larger maybe?
 
About 1/2 way or 2/3 way down the neck you are coming to the part that is thicker because it was shoulder as a 6BR, this may be where you are getting tighter. Many neck turners will handle this in one pass but I find it easier to do it in two passes. My Pumpkin will do it in one pass but its easier in two passes so I make a rough cut with my K&M first.
 
The redding sizing button may not be sizing the brass up enough to slide nicely over the Sinclair cutter mandrel. Most neck turning tools come with matched sizing mandrels for their neck turning tool, use them. Brass shrinks after being sized... the K and M as well as other size the brass a bit larger, allowing it to shrink down to the size the neck turning tool needs it to be to fit the cutting mandrel for same brand.

Paul
 
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I have the redding button plus a sinclair expander + turning mandrel. When using the sinclair expander (after sizing up with the redding tapered button) the turner still goes over very heavily. The thickening towards the neck-shoudler line might indeed be causing it. I've just tried to make a smaller first cut, but even without the blade in place (mandrel only) the brass starts to yank my turner and it gets very hot.
 
I would guess that Dick has it right.

I know with my Sinclair neck turner the cutter is quite wide. It makes a nice smooth finish but is not good at taking a deep cut. I use another tool for a deep rough cut and the Sinclair for a smooth final skim cut to finish.

If you are trying to cut deep with the Sinclair this could be the issue.

Also worth lookinmg at is the thicker area of brass at the bottom of the 30 cal neck will spring back more and may well be a tighter fit on the mandrel than the rest of the neck. From your description I am not certain if you meant the neck is tight on the mandrel or the cut gets hard. If the fit is tight on the mandrel and it is hard to hold even when no cut is being taken all you can really do is try a larger expander mandrel.

Another factor that may have a bearing, I have seen this on necked down cases (17's), is that the reformed brass will have become harder than the parent case. The turner will take more effort to take a cut in hard brass than more malleable brass.

Bryce
 
VT52 said:
I have the redding button plus a sinclair expander + turning mandrel. When using the sinclair expander (after sizing up with the redding tapered button) the turner still goes over very heavily. The thickening towards the neck-shoudler line might indeed be causing it. I've just tried to make a smaller first cut, but even without the blade in place (mandrel only) the brass starts to yank my turner and it gets very hot.
Click to expand...

Well then you need a mandrel that enlarges necks slightly larger. my K&M mandrel takes 6mm all the way to 30 in one step but its diameter may well be totally inappropriate for your Sinclair turner.
 
Another question for you would be what lubricant are you using? Pumpkin (Don Neilson) uses a mix of STP and Mobil 1 90 wt as I recall. We have had it for so long I forget what we used to make it.

Paul
 
Vt

I do not have a 30BR, (I have a 30ppc), but I built one for one of my best friends, and we shoot it. He had the same problem when necking up the 6BR case to 30, that, and the things getting real short, running out.
I made him a fireform rig to blow the cases out to 30 the same way I do my 30PPC, and my 6PPC.
All he does is load the 6BR case with a cheap bullet and about 30 grns of 133, and fires. The things come out just great, ready to turn.
I know that a lot of shooters do not have the option of making cases by expanding them in the proper fireforming barrel, but if you ever do it, you will never go back.......jackie
 
Yep, I had the same problem

I had the same problem and I have 2 of the Sinclair model 1000 neck turners, a 6mm and a 30 caliber...Everytime I use the expander it will not open up the case enough to keep the turning madrel from binding...:mad::mad:
I just take the turning mandrel put it into my lathe and use some 400 then 600 grit sandpaper to reduce the size by about .001"...The problem will go away and life is good...;)
I think the people of Sinclair need to reduce the turning mandrel or increase the size of the expander by .001"...:cool:
 
Ditto

With my sinclair did the same thing just used my cordless drill and polished the mandrel with 600 then 1000 then brasso works alot better still hangs up once in awhile might repeat the 1000grit and brasso to get it perfect.
 
You need a slightly larger expander

I just finished turning some new .30 BR cases this evening. After the Redding tapered expander I had the same problem you write about. So I'm using an RCBS .308" expander to expand the necks just a touch more. This is not a decapping expander but a .308" plug that expands and can slightly flare the mouth for cast bullets. (I'm not flaring the mouth!) You can make or buy something similar. I have several for other calibers I made from drill rod and some store bought versions for a Sinclair body. You need one just slightly llarger than your tapered expander -- .0005 larger??

I'm also rotating the case in the shell holder and giving another stroke to the press. So over the expander once then a second time after rotating the about 100 degrees. The cases still fit snug but the stubborn little donut is all on the outside of the case so I cut it right off. I'm using a Sinclair tool turning in my drill press at 470 rpm. I hold the cases in an old Forrester colett style holder.

I've tried lots of lubes and the very very best I've found is ProGold/ProLink chain lube - http://www.progoldmfr.com/products/prolink.html
You can buy it in bicycle shops. I put just enough to cover a dime in a bottle cap and then dip each case mouth just before putting in into the turner. I get a great smooth finish, no galling. I tumble in dry media to remove the lube.
 
Don Neilson (Pumpkin) and Ken Markle K&M have that extra expanding figured in to their mandrels when you buy them. That's why the expander and the turner are different. But you still need good lube, and the right speed of cut, also if you heat up the turning mandrel and it grows things get tight. Carbide doesn't hurt either.

Paul
 
I use the K&M tool to cut, and their expander to open the brass to .30. I set the tool to just scratch the heavy side of the first part of the neck, and cut the thickened part away at that setting. I then set the tool to cut to the finished thickness, and cut them to size on the second pass. This method has worked perfectly for me so far.

-Dave-:)
 
Inside necks

When you neck the 6BR case to .30, the inside of the neck will be funnel shaped...bigger at the front and then decreasing in diameter as you get to the new neck/shoulder junction. I've made well over 1,000 30BR cases from the Lapua 6BR brass and sometimes this 'tight' area occurs over a pretty short length and sometimes it's more gradual. I assume the particular lot of brass contributes to this, although annealing the new cases before necking them up shows the same tendancy, even within the same lot number. A mandrel diameter that's small enough to fit the tightest portion of the neck i.d. will be too loose in the front part of the neck for best results.

That's why firing the 6BR case in the 30BR chamber makes for nice neck turning..the inside of the necks are a nice, uniform dimension before turning. I've done lots of 30BR cases this way in the past. Even though I use another method now, my own preference is to have the neck i.d.'s as perfect as I can before outside turning.

But even when done by the simple 'neck up' process and with a mandrel that doesn't fit the entire length of the neck well, these 30BR's still just shoot like crazy. Pretty amazing cartridge. :cool:

Neck o.d.'s are fawned over and cut to the .0001's... while the neck i.d.'s can vary by a full .001 or more and are ignored. :confused: And the neck i.d.'s are where the real 'business' takes place. ;) :)
 
I haven't seen this mentioned yet, but K & M makes a carbide turning mandrel with a reamer ground into the front end which will take the little internal doughnut out. You just have to be very careful getting it started into the neck because it's very sharp & can gouge the case mouth real easily. I would recommend that you use that turner with corresponding Expandiron to do an initial turn to true the necks & remove the inner & outer doughnuts, then do a final turn with another K & M turner. That being said, I use a Pumkin in one pass, but I have purchased several Expandiron mandrels & found an expander mandrel that works with my turner mandrel. It's probably a hair loose going in, but about right in the tight spot, and feeding the turner in fairly aggressively seems to burnish the neck down onto the mandrel for a good concentric fit. After turning, my necks are +/- .0001 or less in neck thickness variation. Also. I am still convinced that a re-anneal is in order for optimum results, though not necessary from a practical standpoint.
 
Thanks for all the replies!

The neck binds onto the mandrel, I tried it without the blade touching anything and it still binds. I will try the fireforming trick when I get the chance.
 
Vt52,


Based on your last clarification I have to agree with those who're telling you that the thicker shoulder brass is springing back, that the i.d. is funnel shaped or gets tighter as you go in deeper. The i.d. is funnel shaped because the brass in the front half of the neck is thinner than the brass in the back half. When it comes off the expander mandrel the hole is left tapered, the I.D. is tapered. In my opinion the correct way to address this is to bring the i.d. back into parallel somehow, probably by reaming.

IME The Ken Markle mandrel with the reamer ground into the front will NOT address this. I've got several of them and find them moderately useful for removing very small sizing-induced donut rings but the K&M reamer will not ream a long portion of neck, nor will it address a taper well. The K&M tool is only for removing small sharp donuts.

I suggest that you try an inside neck reamer like this one >>>> http://www.kinneman.com/bwlongsnipe1.html <<<< and then neck turn.


If you choose not to ream then the method outlined by Dave Short gets my vote. Two passes, one initial pass to get rid of the thick portion and then a clean cut all the way. Unfortunately this still leaves you with turning on a tapered neck. And you will need a larger neck expander mandrel.




al
 
alinwa:

After expanding my necks on my mandrel, they measure .3060 at the mouth and decrease to .3045-.3048 at the neck/shoulder junction. I then bring the neck i.d. to .3070 and neck turn them over a .3065 mandrel that I made from a Sinclair .338 mandrel. I've got 4 different size .30 cal. mandrels for my Sinclair turner in .0005 increments, all made from the .338 mandrels turned down on my little bench lathe.

With the neck i.d.'s @ .3070 and the turner mandrel @ .3065, the necks barely get warm no matter how fast you neck turn. When they come off the turner mandrel, the inside of the necks are nicely burnished (as Joe Entrekin points out) and still measure exactly .3070.

I then anneal 'em and run 'em through my full length bushing die with a bushing .003 under what a loaded round measures. At this point they're cocked, locked and ready to rock. :D I jump right to load development with the first firing.

Good shootin'. :) Al(notinwa)

"Going it alone is the best way, 'course. With a partner, there's always murder lurkin' about."
Walter Huston 1948 'The Treasure of the Sierra Madre'
 
@Al-notinWA: How do you bring the ID to .3070 uniformly?

@Al-inWA: Indeed another option, inside neck reaming. Hadn't thought of that one.

I'll try to measure the inside diameters tomorrow. This batch of brass comes from a new box, can't remember my earlier batch having this much of a problem.

Thank guys!


JimInNL
 
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