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

I don't want to turn or ream necks, just sort them and toss them.

Can I get by with a plain old ball micrometer? Do you just spin the brass on the micrometer and get the readings? What is your keep and toss measurement?

Sinclair sells a pretty nice bench top unit (~ 75.00 without pilots), but you have to buy pilots.

I can get a decent ball micrometer for under 50 bucks.

I've been around that block.

For sorting and tossing do yourself a favor and get the Sinclair or Redding tool that uses pilots and a dial indicator.

mathman

It is the neck wall thickness that varies, just turning the case and measuring the OD ,isn't going to tell you much

No, I am talking about neck walls as you stated.

Just found the Redding on sale and ordered it. Looks to be a great price, and a real sale, not $1.00 off..........

http://www.midsouthshooterssupply.com/item.asp?sku=0007626400

Found out about the sale here:
http://64.233.169.104/search?q=cache:OxDnMmIKaUEJ:www.6mmbr.com/casenecktools.html+how+to+measure+case+necks&hl=en&ct=clnk&cd=2&gl=us&client=firefox-a

Mathman- any of your usual good tips on case prep are appreciated per using this tool. I got the Sinclair concentricity gage, and had to bring it up a notch.

You'll find that a lot of the neck runout people blame on those evil expander balls really comes from neck walls that are not even around their circumference.

I've demonstrated this with a plain vanilla RCBS FL sizer I use a lot for loading 308 ammunition. If I size a piece of brass with no expander ball and check it the neck runout is basically surface noise from the brass moving under the tip of the dial indicator. If I put the expander ball in place, unscrewed a half turn from locked down, and size a piece of good brass the runout on the neck will usually show a thousanth or less and always less than two thousanths. Doing the same with a piece of brass with a bad neck will make the runout go wild.

Your seating die will have an easier time putting them in straight when the brass is even and sized straight too.

mathman

Any measurement using a pilot and checking the outside variance will NOT give you true readings of variances. The inside of neck walls can have depressions so that the neck wall doesn't contact the pilot therefore giving a false reading. Measuring the neck walls with a ball micrometer in several places will give a truer reading. Even then you must measure in multiple locations on each neck and there is still the possibility of missing some of the extremes. Tools with the pilots are a start but they aren't accurate.

bobski, what about using resized brass? Won't the fireformed case be relieved of depressions/dents?

I use the Redding tool on resized brass.

If one trims for length and simply looks at neck thickness the evidence is typically obvious to the naked eye. Tossing rejects is simply a waste of otherwise fine cartridges. Likely, you will find the variation you are looking for, and as a cure I suggest using a tool that simultaneously reams and turns the neck. Passing the neck wall between a reamer and cutter will generate a more consistent product than tools that simply work one surface or the other. The process halved groups sizes for a 7 mm Mag and 22-250, so now I simply turn necks on everything I own.

1mimute, I am hoping for a low cull count. Down the road, I may ream/turn, but I am just a hunter that likes reloading. The thing that has made me decide to check for concentricity and now measure necks is this. I freaking hate it when I am trying to find a new load, and get unexplained flyers. I am hoping to eliminate that.

This is from Mule Deer. Not saying what ever he writes is the gospel, but he has more resources than I do to check such things.

Over the years much advice about "uniforming" cases has been printed. I've tried it all, from reaming primer pockets to weighing cases to removing the little burr on the inside of the flash-hole. All these details may have some slight effect on benchrest ammo, fired in rifles capable of one-hole groups, but even some benchrest boys have given up on most of 'em.

Why? They don't make any difference. The only case dimension that seems to help shrink groups is uniform neck thickness. Ideally, necks shouldn't vary more than .001" in thickness. Before measuring, most bulk brass must be run over an expander ball to remove dents. Otherwise you'll be measuring dents, not brass.

All of this takes time, but you only have to do it once. I buy most of my brass from Midway USA (5875 Van Horn Tavern Road, Columbia, MO 65203) in 100-500 round lots, and sort necks on any batch from Remington or Winchester. The reject rate usually runs between 5-20%, and you can use the rejects for offhand practice or dummy rounds--or neck-turn them to the same uniformity as the "good" cases.

I used to turn necks, but no more. As a general rule brass with bad necks is lopsided all the way down through the body. It may be straight after it's fired, but won't be after full-length sizing.

I don't bother weighing brass anymore, either. Most of it's just too uniform these days. The first time I've weighed brass in a couple years was yesterday, just for this article. The only batch that varied more than 2% was some Winchester .300 Savage brass, at 4.8% still only plus or minus 2.4%, which matters not at all in the real world. I use the same brass for handloads in both of my Savage 99's, one peep-sighted, the other scoped. The peep-sighted rifle (a takedown) will average a little over 1" for 3 shots at 100 yards, the scoped rifle under .75".

Nope, all it does is "transfer" the depressions to the inside. When you pull an expander through, that transfers them again to the outside.

All this is a tempest in a teapot. Generally it doesn't matter that much in big game rifles anyway unless you're way off in extremes. The .001" variance is a good general rule. I've never been able to see any difference in those with a bit more variance and I use .0015" as my breaking point. I'm unsure what even .002" has shown in accuracy. Even with minimal variance, most hunting rifles won't show enough difference in group size to really tell much of anything, it's just a matter of where you want to draw the line. You still have variances from case to case in the elasticity of necks. As long as you are concentric and your wall variances aren't extreme enough to vary group size out of a hunting rifle, it doesn't matter much.

This is the type of tool you want for proper readings on neck wall thickness. LINK

Very good advice.

Hey Sakoluvr

I measure neck thickness 2 ways. The easiest way is with a Casemaster or similar gauge



Note the mark on the collet that comes down onto the neck. The trick for me is to lift the collet, rotate the case and bring the collet back down. If you try and roll the case to get a continuous reading it is hard to get a consistant measurement because of the difficulty holding the case level.

I also have a ball micrometer



which is more accurate but much harder to use because it is awkward in the hand. With the ball micrometer you will soon discover that the thickness also varies with distance from the shoulder.

Sorting by neck thickness would seem like an exercise in frustration to me because of the many differences in neck thickness depending upon where on the neck the measurement is taken. For instance with most Remington brass the neck thickness varies .002" or more on every case, if you find a case that seems consistant just keep measuring in different places and you will find a significant variance, so how do you sort it? Nosler brass is better and so is WW brass, IME, your results might vary.

I usually neck turn new brass after neck sizing with a Lee Collet. The Forster turner I use then fits very tight in the neck and depending upon the original thickness I will turn then entire neck




especially in a tight necked gun. Or I will do a partial turn (no good pic) where I turn 75% of the neck so all of the neck is within .0005" of the same thickness.

I am not at all sure how a variance in case body brass thickness would transfer to the neck brass again or how it would affect case concentricity. Possible the case expansion characteristics would vary, but how much and if you PFLR with shoulder contact then what would it matter?

But to answer your question, I can measure the relative neck thickness of brass much much quicker with the Casemaster. It also has the advantage of being useful in other ways also.

Woods, Welcome to the campfire. Great illustrations. Thanks, and I hope you post often here.

When reaming and neck turning in one pass, how is the "depth of the cut" adjusted?

With factory chambers, does neck turning/reaming make sense? Can concentricity be improved by neck turning or reaming or both.

Nope, not in my opinion. Brass is too cheap to mess with a lot that has extreme variance. Much brass is available from all our domestic manufacturers whose neck wall variance is acceptable as is.



Yes. If the brass is way off, skews the bullet when seated, or otherwise affects concentricity, obviously uniforming the walls will help. Reamers that are free floating such as those by Forster, can cause more problems than they solve. Unless used in a reamer die, the reamer will follow the path of least resistance when put thru a neck. The hole it reams can be stovepiped, at an angle to the concentric axis of the case, making the problem worse than when you started.

I don't ream and neck turn in one pass. The K & M turner does have a cutting mandrel with a cutter on the end that is made primarily for do-nuts, http://precisionreloading.com/KMProducts.htm



"K & M has specially designed a new carbide mandrel that has four flutes for removing the "dough-nut" that is located at the neck-shoulder junction of a case. Removing this extra material aids in a consistent high volume flow of powder gas. A small difference in the shape and diameter of the hole makes a huge difference in performance. This new carbide mandrel will also cut the extra material out of this area if you have changed the neck to a different caliber. This mandrel works while you neck turn, so you will not have to perform a separate operation."

It doesn't really "ream" out the neck like a regular reamer, http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=590193&t=11082005



that attaches to a trimmer. I don't know of any equipment that both inside reams and outside neck turns at the same time. Anyway, I don't ream so perhaps someone else can help you with that.

With outside neck turning the depth of cut is adjusted on my Forster turner by loosening the lock on the cutter blade and turning the dial to move it in or out



There is a little trial and error to get it just right and you do need a good way to measure neck thickness.

IMO, neck turning does make sense, even in factory chambers. It helps to make your bullet release a little more consistant. It will reduce runout just by physically removing the high spots on your brass neck but also by making the neck expansion more consistant. Of course, this is my opinion and largely unproveable and others opinions might vary.

I do know that outside neck turning with my Forster hand held is one of the less odious tasks, only has to be done once and doesn't take that long. I would recommend the Forster turner over the K & M, even though the K & M has the cutting mandrel because the Forster turner has a wide blade that makes for a smooth cut



which I do not think the K & M has since I have heard others complain about the circular grooving with the K & M. Also, the hand turners are the way to go. I originally used a Lyman turner on a hand crank type of trimmer and it did not do a good job.

bobski, thanks. I value you your opinion, and many opinions are more data for me.

woods, why turn all the way into the shoulder? It looks like you went a little past the neck/shoulder juncture.

If you remove brass from the entire neck (all the way around), does that mean you are cutting too deep b/c only part of the neck wall is thicker in an area or two? Or do you just bring it all down to a "uniform thickness?

I love pictures.