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

I have the K&M. I did get some grooving initially, but now I just "feed" the case in slower and voila! no grooves. I use a small cordless drill to turn the cases - the hand tool took way to long - so it spins fairly fast. The other advantage of the K&M - you can put a dial indicator in the end opposite the cutter and measure neck thickness as you go - this alone makes the K&M much better in my opinion. I'll post a pic later.

Woods:
"I don't know of any equipment that both inside reams and outside neck turns at the same time."

RCBS makes a cutting/reaming tool. It is not something I would use in a commercial setting, but it works for me. Setup is a little tedious, but then again, anytime one is striving for precise dimensions some set up is always involved. I use one and simply use feeler guages to set the reamer/cutter span. Given that most brass only receives a single treatment, it's not such a tedious task.

Edited in: Here's a link.

Link to RCBS reamer/cutter

I get measurable improvement in run out and suspect that neck tension and release of the bullet are more consistent too. My practice is to fire form, neck size, length trim, anneal, then neck turn/ream.

I do not have any custom chambers, but experienced almost a halving of group size with my long possessed 22-250 and 7 mm Rem Mag. Both of those were running Remington brass that had several firings, and the issue was visibly obvious by looking at necks after length triming (thick/thin sides). Both units had shot well, but I would get those frustrating 1 out 5 or 6 fliers before I started turning. That's not the case anymore, and they both stack them in there. Since then I've not done any before/after comparisons, as all cartridges/calibers are exposed to the same treatment as standard operating procedure.

If I indeed owned some tight necked units I would probably ream/turn to a new surface through out. I select a thickness based on published cartridge dimensions (thickness = (cartridge outside neck diameter minus caliber)X 0.5), and my cuts usually expose about 65 to 75% new surface on the outsides of necks. That being, I'm likely a thousandths or so short of perfection.

The process may not help in some instances, but quite likely, it certainly won't hurt anything either. 1Minute

1minute- if the neck diameter of a .308 is .343, then .343-.308= .035 x 1/2= .018 So is that how much you set the cutter in to remove that much brass? You use feeler gages to adjust that?

.343" is a fired neck or chamber diameter. You need to use the neck diameter of a loaded round, typically between .331" to .338" depending on brass.

Some LC stuff I recently measured had .014" neck walls.

whoops, thanks m

Yes, that's the math process although 0.018 sounds a little thick from memory. I don't own a 308, so can't comment on the specific values. With a tight throat unit one would go to the dimension needed to chamber a loaded round without pinching the neck. My feeler guage set has all possible combinations of material (like 2, 3, 4, 5, 6, 7, 8 thousandths etc), so they can be stacked together for any desired span.

Being away from my notes right now, values between 0,012 and 0.014 come to mind for the calibers I own.

Yep, .0130 or .0140. I originally used the fired case dimension as mathman pointed out. Does the little micrometer wheel give an accurate reading when zeroed, or are feeler gauges a necessity to double check?
Is the cut surface uniform, or are areas "skipped" where the brass is not thicker?

Sorry about all the questions folks. I like learning new areas of reloading.

Hey Sakoluvr

Turning a little into the shoulder is supposed to mitigate the development of do-nuts. Here is a link to more than you will ever need to know about do-nuts http://home.comcast.net/~jesse99/doughnuts.html

You have to evaluate your situation to determine whether you want to turn material off all the way around or just hit the high spots. With the measurement you gave of .343" for a 308 caliber chamber, I would do the math like this

.343"-.003"(minimum clearance around neck)=.340"-.308"=.032"/2=.016"

What that means is that you do not want brass any thicker than .016" on either side so that you have at least .003" clearance around the neck brass. So if you happened to buy some RWS brass that was extra thick and varied from .017" to .019" then you would have to turn. If you have some WW brass that varied from .014" to .015" then turning is not required and you can choose not to turn or clean them up to a consistant .014".

The opposite kind of scenario is like in my 6.5 rem mag with a Douglas barrel that the smith chambered with a .292" neck, the math would be

.292"-.003"=.289"-.264"=.025"/2=.0125"

The only kind of brass that I can buy is Remington and it varies from .015" to .017" and I have to turn that all down to .0125". Now that is some serious hand cranking and I usually do it in 2 steps because the cutter binds when you try to bite too much off at one time.

Most turning will land somewhere in the middle of those 2 situations but it depends upon your chamber and the batch of brass you have. My Hart barreled 280AI has a .313" neck and the Nosler brass I use is a very consistant .013" to .014" and that works out to be just about what you want to turn for a custom neck.

1minute, which one of those tools turns necks and reams necks at the same time? I don't think it is the 3 way cutter



or the pilot reamers.

Sorry, no pics this time, but BTW, isn't the 6.5 rem mag the original short magnum?

woods- sent you a PM.

Woods:

Lets try this Midway link. The photo does not show a reamer installed. Sorry about the first pass. 1Minute

Midway link for reamer cutter

Went back in my records - grooves disappeared when I started using the cordless drill to turn the case - like I said, just feed it slowly into the cutter. You cannot feel any grooves whatsoever!

I;ve come to the conclusion that this is like everything else - it's nice to have choices, and some will like these and some will like those . . .

Here are the pic's:

K&M Tool w/ dial indicator attached - makes it very easy to adjust, and you can measure neck thickness alone without a separate tool. Alsl notice the adjustment on the end of the pilot - excellent for controlling the depth of cut into the shoulder.


Here's a piece of 338WM brass that was recently turned - barely into the shoulder and no grooves.


This is the adjust for the cutter - note the threads inside. The cutter itself threads (via reverse thread) into the adjustment screw. One full turn is only about 0.0025" if I remember right - very good for fine adjustment of cutting depth.

Here's a link to an excellent case prep procedure (maybe a bit overboard for our hunting rifles, but still an excellent read):

Case prep procedure

Thanks 1minute

I see how it works now, like a hand cranked turner with a reamer for a mandrel. Reading the last 2 product reviews would make me hesitate to purchase one though although I like to reserve judgement until I try things myself. It makes sense to me that if you have neck sized to uniform the inside of the neck which pushes all the variations to the outside of the case, then outside neck turning would be sufficient.

Hey TXRam (do you shoot at American Shooting Centers?)

I am not badmouthing the K & M neck turner at all. It is capable of doing a couple of things that the Forster is not, like the cutting mandrel, the pilot depth adjuster and the dial gauge. It is an excellent instrument and I have experimented with one at a friend's house when he got his. Sometimes I wish I had sprung for the K & M but most of the time I love the wide blade and simplicity of the Forster. The cutting mandrel will scar up the inside of the neck unless you get the expanding mandrels also. Add in the cost of the individual cutting mandrels and it can cost much more to do about the same thing.

I've seen that article before and that is where the idea of turning a little into the shoulder came from. On the Forster turner instructions if says in bold not to turn into the shoulder. I alleviate the do-nut problem by sizing with a washer on top of the shell holder anyway



and leaving the shoulder/neck junction chamber size



but that is another whole separate discussion.

woods, I totally agree with your points - that's why I said that it's nice to have choices, and be able to pick the tool/rifle/caliber/cartridge/... that's best for each of us. I don't use the cutting mandrels - like you, I feel outside neck turning is all that is needed if you expand the neck to uniform the inside, which I do with the K&M expanders.

I have never shot at American Shooting Centers, but I would like to - have had a hankering to do some longer distance shooting than is available at my range (PSC - Pearland Shooting Club).

I use the Redding Competition dies, and I do not size the neck all the way to the shoulder - same principle as your technique with the washer.

Woods:
"It makes sense to me that if you have neck sized to uniform the inside of the neck which pushes all the variations to the outside of the case, then outside neck turning would be sufficient."

I think I know what you thought you meant, but I'm not sure you said what I think you thought. But then again, maybe you did.

We are likely discussing the effects of a flea on an elephant's ass here. Given that metal can both flex and spring to some degree, I don't think that neck sizing or expanding literally pushes all surface variation or imperfections to one surface or another. Reaming or cutting independently will allow some flex of that imperfect surface away from ones cutter. When the material is simultaneously passed between 2 cutting surfaces, however, that potential flexing escape route is eliminated.

My issue with the hand cutters is that I doubt that I can hold my cartridges perfectly square with my cutting implement. I know a mandral helps, but it is only grasped by a short section of neck and one may still induce some out of line flex.

The rotary reamer/cutter implements have their issues too, as there is typically some play in the implements we mount our tools on. If we all had 5 hp mega dollar lathes, we could eliminate that issue. I think the biggest criticism of the RCBS implement is setup difficulty. That could probably be eliminated with some design changes and development of a $400 reamer/cutter and more secure cartridge holder. I probably wouldn't buy one though until I took on the benchrest circut.

It's been fun. Shoot fast and straight. 1Minute

Hey, let's talk about do-nuts. Are they inevitable if you turn brass? 1minute, I want to just remove what needs to be romoved on a lop-sided neck. Do you find that the cutter "skips" the thinner sides and cuts the thicker sides? Looking to improve concentricity and create even neck tension.

Almost. Should you ever full size, or partially full size, the brass is squeezed forward. The thicker unturned part of the shoulder at the junction becomes the donut when this occurs. In benchrest where the cases are mated to the chamber from the gitgo and never full sized, they are avoidable.


Yes, with reasonable brass where you clean up about the recommended 75% the variance will be way down.

bobski, so that is the reason to keep that juncture thinned.

Wondering- you just need to turn necks 1x out of the gate, then go ahead and get into the shoulder a RCH, so when/if brass flows forward with resizing, that spot will be thin and and the do-nut will not form. Right?

Right. Problem is you have no clue how much to go into the shoulder, it's just a guess; too far and you WILL separate and leave neck in chamber and likely at the most inopportune time, like that second shot at game. Also, if there is quite a bit of variance in the necks you know for sure that variance will be at least the same and probably more in the shoulder and body and when you get a donut it will NOT be uniform; one side will always be thicker than the other and will skew bullets if they are seated below that.

For the record, I see far more disadvantage to turning necks than advantages. As a matter of fact my experience indicated that there was actually a loss of accuracy and except for the couple of tight necked BR rifles I've had, I avoid turning preferring to buy brass that has less than .0015" variance and using it; less problems and a lot less work, but then I HATE to turn necks anyway. I have the Sinclair turner, mandrels and expanders. Sometimes for real expensive brass, or wildcats, you have few alternatives. One alternative is a reamer die which is what I use to make 338 Jamison cases out of 404 Jeffery or 338 RUM. Particularly the Jeffery cases are over $2 each. You'll get a donut in those eventually and at that price it's worth the effort to salvage them and extend their life as far as possible.

Whew, lots of data points to ponder. I don't want to open up a can of worms. I really have the wrong personality to be reloading. Things are never good "enough".