What is it about cases and accuracy?

greg11

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Is it uniformity of weight and internal dimensions? Times fired? Both?

I'm thinking of finding some Lapua brass in the near future, just looking for the skinny.
 
No finishing required and uniform construction

Is it uniformity of weight and internal dimensions? Times fired? Both?

I'm thinking of finding some Lapua brass in the near future, just looking for the skinny.

I don't know where you live but if you can go to a shop where you can see match Lapua brass and compare with excellent but "normally" finished Winchester brass!
With Lapua, you have no finishing to do, internal volumes and dimension are uniform, construction quality is excellent.
With Winchester, you'll get to trim, debur and weight your cases before reloading.
Lapua is supposed to give way more reloads but I limit my cases to 8 reloads so it's not a issue for me.

Alex
 
I have used pretty much all the brands on the market, even milsurp.

What varies is the durability of the alloy and the prep work needed.

Brands like Lapua and Norma are held to very high manf standards (usually) so there is min. work needed to get them shooting their best.

US brands typically need some basic prep BUT I do the same prep regardless of the brass as I have found enough vagueries to never leave it to chance.

For me, the big one is case volume. Weighing a case does not indicate the case volume. If all the cases were machined the same in the extractor groove and all preped to the same external dimensions, then yes, it would work.

BUT the exterior dimensions aren't the same. Just measure it. I really don't think variance in the extractor groove is going to change your groups much.

I have tested brass that were quite wonky in weight but had the identical case volume. They shot great and I recorded some of my smallest groups.

The Alloy used will determine how durable a case will be under high pressure loadings. Here Lapua is some of the toughest alloy on the market. Win would be next. Norma has made some really tough batches too.

Most other brands can be excellent. Some of my smallest groups have been shot with Rem and Fed brass.

But most will loosen the primer pockets after a few toasty loads. The brass may be consistent and give great accuracy but if the brass can't take a beating, many shooters will consider it bad. Of course, that is not an accurate statement but valid from a budgetary standpoint.

So up to this point, there isn't a big deal of difference in what brass can do for your groups IF you do all the basic prep steps. IE. tuning a rifle as best you can with brand X isn't going to drop significantly with a switch to Lapua or Norma.

Some overlooked areas include annealing. This to me matters and should be considered regardless of the brand. All necks work harden with use. Not good for consistent neck tension. Annealing properly can resolve this and should be done every 3 to 4 firings for peak performance.

Case trimming and outside neck turning are ongoing steps like annealing to keep brass at its peak.

Standard chamberings like the 223, 308 will stretch with high pressure loading. After annealing, I will run the brass through the trimmer and outside neck turner. Cleans things up. Keeps everything as consistent as possible.

Brass is not the panacea of accuracy. It is critically important but a whole lot of stuff can be prepped to work. I do not consider brass prep a chore as it is important for me to do regardless of the make. AND I will have to do the same prep work as I use the brass anyways.

Paying for premium brass is a good thing for MANY shooters. It saves them time and gives them peace of mind. confidence is everything in precision shooting.

But after the second firing, it needs the same TLC as anything else.

The one thing you may get with premium brass is better longevity.

I spend more time getting the right powder and bullet combo then brass. These two things have a huge affect on what happens at the target.

Jerry
 
Don't buy Lapua brass with the notion that it will not need to be prepped before its first loading, unless you don't mind shaving ribbons of copper off your bullets when seating. I haven't seen a lot of Lapua brass, but the .223rem stuff I was working with had nasty burrs at the mouths, case lengths all over the map, and very inconsistent primer pockets.

I'm no big fan of Winchester products either but, Winchester brass seems to be working in my .223 for shooting accurately out to 1000yd.

If it were easy to sort cases by internal volume that's how I would sort them, but until somebody invents some kind of SONAR case volume measuring gadget I won't bother.
 
Talk with ten different highly successful long distance shooters and you will get 10 different answers.

Lapua brass is so consistent weight, internal dimensions, neck dimension-wise that it can literally be used form the box, and I have many times. I won the BC Lt. Governors prize using un-turned never fired Lapua 6BR brass and unsorted bullets. ( a 3-600M match)

I divide long distance into three different arbitrary "zones": 3-500M, 6-800M and 900M.
Me myself and I have found that each of these zones has greater and greater requirements for consistency to work.

It is all about consistency.

If I were to place an emphasis on one variable, it would be neck thickness. (I edit to add that by this I mean in terms of consistency, not ".262" br necks, or minimal clearance chambers) Turning necks really pays off at long distance. All other variables are of much less concern with Lapua Brass. I do chamfer case mouths using a cheap counter-sink bit from home depot and it works like a charm. Personally, I think bullet selection and prep has more tangible results.

here is a picture I have taken with brand new Lapua 6BR brass. I have skim turned the brass to even it out, and you can distinctly see how even the best brass on the planet has microns-thick variations.

neckturn3.jpg


On the left, brand new Lapua 6br with factory annealing. The three subsequent cases were all from the same lot of brass and turned without adjusting the cutter at all. the middle two show high spots taken off whereas the third shows it was completely turned down, meaning it had more meat than the middle two. I personally feel this makes a difference at long distance and I tend to it immediately.

I have also found 6BR like minimal neck tension, so I expand all necks after sizing and I anneal after each firing. This results in extremely consistent results.
 
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If it were easy to sort cases by internal volume that's how I would sort them, but until somebody invents some kind of SONAR case volume measuring gadget I won't bother.

Yes, it is BUT you must use fireformed brass that has been trimmed to proper length. Leave the spent primer in.

Grab a fine ball powder WCC680, H110 or something milar. SALT will also work in a "pinch".

Fill one case to over fill with a funnel on top and tap the case letting it all settle. Really want to get as much into the case as possible. Scrap off excess so the powder is even with the case mouth.

Put the funnel on the next case, dump the powder and tap. The powder should settle to be even or very close to even with the case mouth. Repeat.

I allow a 1/16" variance in height either above or below as that works out to a drop of water for volume and really isn't going to affect anything.

You can now very quickly test lots of cases by comparative measure. If case level is much more or less, it will be obvious and these cases can be culled.

In the sorting I have done over the years, the big one was keeping the brass in the same lots. When that was done, I don't remember the last time I tossed a case regardless of the brand or chambering.

The cases varied in weight but the volumes were the same within the same lot. There could be volume difference from lot to lot however.

Try and it and you will see what I mean.

As Obtunded has shown so nicely ANY brand of brass can and will have small manf flaws. This is what we are resolving when we prep brass.

Neck turning to that level of accuracy IS helpful when using bushing neck dies and trying to keep runout in the 0 to 2 thou range. AND outside neck turning will be part of the ongoing maintenance of any case as brass flows.

And it will.

And Yes, there are definitely chamberings of Lapua brass that need more TLC then others. Their recent blue box match stuff has certainly improved in manf.

I use and sell Lapua brass as I do many other brands. I love Lapua when I need to go to number 11 on the dial but the alloy does require attention to sizing for best performance.

That really tough alloy has different needs from domestic brands.

Annealing is really important for best maintenance of the case necks BUT it must be done properly and consistently or you create for more problems then you resolve.

Jerry
 
Obtunded, do you ream the inside of the necks after the first firing? If so, is this only applicable when you have a chamber set up with 0.003" clearance for the neck, or can it help in a factory chamber?
 
From the 6mm br site:

Tight Neck or No-Turn Neck -- What's Best?
The collective wisdom is evolving on this issue. Originally, 6BR shooters emulated what works for the 6PPC--tight .262" necks with a .009" or so neck wall thickness. Now the trend is in the other direction. Many shooters have had great success with .268-.269" necks that allow full neck uniforming with a cut up into the shoulder to block the formation of doughnuts. That said, we are now seeing very accurate rifles being built with .271-.272" and even .274" chambers that allow Lapua 6mm BR brass to be loaded and shot with no neck-turning. The results have been encouraging to say the least. Richard Schatz recently set a 1000-yard world record with a .271"-necked 6mm Dasher. And there is evidence that the longer VLD bullets work best with the greater neck tension allowed by unturned or minimally-turned brass. One well-known shooter says he has seen no loss of accuracy since changing to no-turn necks, and that's how he will chamber all his future barrels. However, most top smiths still recommend turning necks, but not down to .262". A .269" chamber appears to be a good compromise, allowing a quick, easy one-pass turn without sacrificing beneficial neck tension. For a varmint or tactical rifle, the choice is clear, however--go with a no-turn neck so you can spend more time shooting and less time reloading. Both the Lapua and the Norma brass are good enough that you will give up very little accuracy.

I've got a 6mm br project slowly evolving. I'm not planning in competing so I was going to go with no neck turning. What do you guys thing about the above paragraph?
 
I have always shot brass with a min of 10 thou thick necks but max at 12 thou. Provide enough neck tension, durable, easy to anneal.

Add in a couple of thou for clearance and you are good to go.

I never understood the super thin necks having found more trouble then good. Found thicker necks to offer even more problems with bullet release and tension.

So I neck turn to get the thickness where I want and fit the chamber.

I think if you do some more research you will find that pretty much all top shooters will outside neck turn their brass as shown in the pics above. A half or 1 thou on one part of the neck can cause an internal bulge which can affect seating.

Neck turning is a regular step in case maintenance. Don't do it for your first firings, that is up to you BUT you will be turning in the near future as the brass flows.

Jerry
 
In my experience, most of the things that lead to poor accuracy show up in the neck.

You want to check your neck runout and bullet runouts and find the root of the problem when these are high. It often has to do with the die. Floating the die on an o-ring can often help. Or, get a press where the die floats, like the Forster Co-Ax press.

As Mystic points out annealing is often overlooked. I anneal, and not because I think it has any effect on case life. I do it because I measure my runouts every time I load and after a few firings, I see those runouts go up. Annealing the necks gets me back to low runouts again. The advantages of annealing are very measurable.

Having a clean an smooth surface on the inside of the case neck is also important. It gives lower runouts, and more consistent seating depths than when they are rough and caked with powder residue. I burnish the insides of my necks with a bronze brush if I've cleaned the cases with US or tumbling in SS media. If I dry tumble, I wrap a bit of 0000 steel wool around the brush. I also swab out my cases with a bore swab as a last step in case prep. A bit of case lube always gets into the swab, which also give the inside of each neck a very fine coat of lube.

The biggest problems I see, ones which show up in my pressure traces, have to do with interference between the neck and the chamber (more an issue with tight custom chambers). A simple test for this is to take a bullet and slide it in and out of the mouth of a fired case. If there is friction and resistance, it will show up as pressure variations (with usually goes along with poor grouping). One culprit is donuts. A long as brass flows, these show up. I've found them in 308 cases many times. If they aren't too thick, leaving the last 1/16" of the neck unsized keeps them from causing any grief. The other culprit is burrs on the inside or outside of the case mouth (or both). Sometimes its the actual de-burring that causes them. I trim with a Giraud trimmer and it leaves small burrs at the bottom of the chamfer. I always go over my cases with a K&M chamfering tool on the inside and fine sand paper on the outside.

Someone needs to make a de-burring too that is similar to a neck turing tool. It should have an angle closer to parallel with the outside of the neck instead of 45 degrees. I've created this setup in my lathe using a mandrel held in the chuck and a straight bit. Very useful for getting rid of the monster burrs you sometimes get from tumbling in SS media. This has at times given me fits, but I still like the overall advantages of the SS media.
 
Lapua brass comes with the necks annealed... If the dimensions between the neck diameter of the chamber and the neck sizing diameter of the die are close, necks will not work harden with many repeated firings and sizings and should not require annealing.
 
I understand the relationship between bushing dies and how an uneven outer neck can cause an uneven inner neck, and thus uneven tension on the bullet. Thus neck turning is a requisite for using a bushing die. What is the advantage of a bushing die over a collet sizer? I recently made a dummy reload with a fired winchester case that had no neck treatment other than the collet die, and found a bullet runout of under 2 thou (sinclair concentricity gauge).

If neck turning is a matter of maintenance, I think I'm going to buy a second Forster trimmer so that I can have one set up and adjusted for trimming, and one for neck turning.

kombayotch, I have wondered about the consistency of the inside neck surface. A bronze brush followed by light lubing sounds like a good idea, especially as treating the brass in water and not quickly drying can cause some copper oxidation. I had an old batch that I didn't dry properly after a water rinse, and later I saw green oxidation on the inside of the necks.

For convenient deburring, would a Forster 3-way case mouth cutter work?

http://w ww.forsterproducts.com/client_images/catalog19938/pages/files/3-in-1_Case_Mouth_Cutter_3CUT-001.pdf

The outside chamfer is 30 degrees. I have one but I haven't set it up yet. I think it's a great idea because it will make my chamfers much more reproducible on top of saving a lot of time.


With regards to annealing, I don't have the space for an automated setup. I think after a number of firings I'll try the method of propane torch and spinning in a drill+deep socket.
 
I've never tried the Forster 3-way, but I had and RCBS for a while and I found it scratched the inside of the case mouth. When I trim with my Wilson, I use the K&M on the inside and a regular de-burr tool on the outside, followed by a light pass with fine sandpaper.
 
Okay, this is all very interesting (and overwhelming! my head is about to explode)...

But...

Practically speaking, how many MOA will this process amount to? In trying to visualize concentricity and runout, I'm imagining very small tolerances.

I'm also thinking about an eccentric cartridge, placed inside the chamber and fired. I can't help but think that any anomaly in concentricity or runout would be somewhat mitigated by barrel length. I mean, the bullet is wider than the barrel, so, it's being squeezed and forced down that pipe. Would variations as small as .005 runout not be negated by the vary tight and restrictive path the bullet is forced to travel?

However, in imagining this stuff, I also picture a variation in runout having an effect on how the bullet "impacts" the lands of the barrel. This, in my mind, could "squish" the bullet asymmetrically (even minutely) which would effect it's flight. No?

So, in one sense, I picture runout and concentricity only being practically important at distances grater than, say, 500m? But on the other, if I'm right about bullet deformation, I could see it impacting the flight path dramatically...

I could be wrong on both counts, but I just seem to think this stuff only really comes into play (in a major way) at larger distances. at 200m, would you guys say these adjustments to the case amount to 0.1", 0.2", more?
 
All this seriously anal brass prep MAY shave off a tenth minute with a very accurate rifle.

Powder measuring is far more important.

BUT when you want all your shots to go into the same hole, everything matters. It is the stacking of tolerances that get you.

I use the Forster 3 way cutter and LOVE IT. An enormous time saver and does a superb job.

Well worth the money.
Jerry
 
All that anal, snikity, time consuming tinkering for a 1/10th. A fly itch my nose and kick off a shot 1/2 moa into the ether, or just breathe wrong and beat that dead horse more.

This is all fine for the mental satisfaction that you have the tools (which is very important in our game and not to be little it) but I now may have to load and shoot more, and tinker less!

Thanks Jerry....my wallet feels lighter already:)
 
Neck turning itself might give 25% smaller groups

Hi all, I'll find the link later but read a very interesting article in Hodgdon Reloading Manual about what really mattered in reloading and from what I remember, proper neck turning might yield at 25% decrease in group size.

I'm shopping for a case trimming/neck turning solution right now as the result of this article and having prepared 200 cases of Winchester brass using a 25 year old RCBS Case Trimmer - 2!

Alex
 
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