Home Forums Reloading Big Game Rifles I want to measure case necks, need advice.

Let me throw in my .005 cents worth on neck measuring turning.
I modified my RCBS Casemaster to accept RCBS flash hole pilots for measuring neck wall thickness. I found the factory set-up too slow and too susceptible to error for me.

If I do decide to turn necks--which is rare for me with hunting rifles--I run each case over a Sinclair expander mandrel first. this transfers all the irregularities to the outside of the case to be turned off. I then turn the minimum amount of brass off the get the necks to .001" or less variation in neck wall thickness.

I use a Sinclair neck turner NT 3000 and turn down as far as the cutter will cut. I have never had a donut problem.

I also use an expander ball when sizing as much as I can. I think this is especially important with unturned necks as it keeps all the irregularities n the outside of the case neck where they won't affect bulelt seating and bullet pull.

Blaine, quit making things so simple.

I decided to turn necks, just to see how it all works, and learn and try something new. I opened up the necks first with a button, then used a Redding case neck gauge to sort the brass.

I sorted brass, and separated out everything >.0015". I took those (~15% of this lot), and made my cutter adjustment on them. I turned until I got at least a RCH <.001".

I am thinking that now I can turn the rest of the cases in that lot with the same cutter depth.

BTW, this is for hunting rifles.

My RP .308 brass gave me ~18% > .0015".
My RP 7-08 brass was <10%.

Mathman,

Before measuring runout, did you first measure neckwall thickness to determine "good" vs "bad" brass?


Casey

Donut update

I have a Hart barrel 280AI with a .313" neck, I turn necks to .0125" so the math is .284"+.0125"+.0125"=.309" which should leave .004" clearance.

Well, I definitely have a donut. This shows how far the bullet will go into a fired unsized case


So I sent off for a Forster reamer not knowing if I would need a hand crank trimmer or if I could use it in my Forster hand turner. It came in and, thank you Forster for being a fine company, the reamer and the hand turner mandrel are the same size


The case before I started measured .0125" neck thickness


and looked like this inside (you can't see the do-nut)


Then I locked the reamer in the turner and adjusted the blade


to ream the inside and turn the outside (just a touch up since these had been turned when new) at the same time


The reamer took a little off the inside and followed the neck without a wobble and the donut was gone-gone, bye-bye
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0717.jpg[/img]

The case was reduced in thickness .0005"
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0718.jpg[/img]

The inside of the case was a little rough
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0721.jpg[/img]

So I chucked it in my Zip Trim and steel wooled it
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0719.jpg[/img]

and it came out smooth and shiny (well at least smoother and shinier)
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0720.jpg[/img]

So I have come to the following conclusions:

1. If you have a factory chamber and substantial neck clearance then you probably won't have a problem with do-nuts even if you have them
2. If you have a tight necked chamber you can turn your necks for .003" or .004" clearance and get rid of the do-nut with the Forster reamer

BTW, in answer to your first question about what to measure the case necks with, I just recently got a Holland's micrometer holder and it is like having a third hand
[img]http://img.photobucket.com/albums/v663/bwestfall/CASE%20PREP/DSCN0727.jpg[/img]

Big difference, I'm as happy as a gopher in soft dirt! Plan to try 5 identical loads with the do-nut and without the do-nut to see if I want to get rid of them or not.

woods, once again thanks for your great illustrations, and taking the time to share them. What brand mic is that?

It is a Frankford Arsenal http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=257288 . I have had trouble with Frankford Arsenal stuff before but this micrometer seems to be doing fine.

and the holder is a Hollands http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=798812

Hey woods, you're a helluva salesman! I'm going to buy that stand; the Starret runs much more than that and it looks like it will do the job, thanks. Bet you could convince someone to go into a cave after a bear!

I too have managed to get rid of some small donuts with a floating reamer. If you go in slowly and not cut too agressively, and if the donut isn't too much larger on one side, you can. However, I'll repeat, the reamer in addition to cutting also slightly expands the brass so that when you are done there is a bit of springback. Where the donut is located you can't quite reach with the tube micrometer but if you split a case and measure from the side you will note a difference measured in the .0000".

bobski, you must be as much a discerning guy as I am a salesman!!

See this bear


this was in Colorado and we did track this wounded bear to it's hole under a rock as big as a house and I did talk the smaller buddy on the left into that hole after that bear! I told him I would gut it if he went in and got it. We heard it die or at least I was 90% sure it died. He did complain a little about the spiders and big claws staring him in the face when he was far enough in the hole for me to just be able to see the soles of his boots. Of course it was hard for me to hear him complaining much cause I was laughing so hard!

Hey, wait a minute, you don't know a guy named Hot Core do you?

Back to the subject, you don't think that having a outside turning blade on the outside and a reamer blade on the inside will negate the effects of springback?

I'll be damned! From my past training I learned to be a good judge of character and I thought I was. I had NO idea this might have been the case! Neat story and good pics. Are you the guy on the right? You ARE one helluva salesman. Remind me never to go hunting with you!

What kind of name is Hot Core? The closest to such a name I've come is the Hogg sisters in Houston, Texas. He was an old oilman and may have been involved in the beginning of Humble Oil, later to be Exxon. He named his daughers Ima and Ura. Ura died before I moved to Houston but Ima was then an old lady that was quite a philantropist; very well known in Houston in the 50's and 60's. I can't imagine Mr. Core naming his son "Hot". Are you joking or does he have something to do with Speer bullets?

Yeah, if you can work both sides concurrently that would take care of the problem. I never figured that part out except for that old tool I mentioned earlier. Reason I know of the springback is that after using the floating reamer I've tried expanding then turning the outside. The cutter never touched the upper part of the neck but when I got to the base, the site of the donut, the cutter started taking off brass, and on one side more than the other. That's when I split a case, measured, and sure enough there was a slight disparity, don't recall the exact .0000". That's when I went to the reamer die and that took care of the problem. I'm sure your way would also do it. But then it really doesn't matter much if the bearing surface of the bullet never reaches the donut when seating it. In my case I was working with a short action that required all but the lightest bullets or boattails to seat at or below the donut to fit the cartridge in the magazine.

Hot Core, The last word in reload methods and tooling...
Very knowegable but ................

Woods has already cost me $$$.$$

Remind me to tell of the time when I talked another buddy into catching this rattlesnake alive so we didn't booger up his head with birdshot



I had him put it in a 5 gallon bucket so I could shoot it once right in the top of the head with a pellet gun. I talked him into it by telling him I would pay for the skin mount and we would trade off putting it on our walls. The ungrateful bastard came by the other day and saw it after 12 years, remembered the deal and wanted it back!



Seems there would be no springback issue if the brass were being cut from both sides concurrently. Where would it spring to?



I guess he doesn't fight his pressure wars and bad mouth Stoney Point "thingy's" over here, does he?



Can I interest you in timeshare on a 6' rattlesnake skin mount? Maybe we could change that $$$.$$ to $,$$$.$$.

Looks like removing the do-nut has a positive influence on accuracy