6PPC Neck for Norma and Lapua Brass

H

haweskg

Guest
Hello All,

I'm building a 6PPC LV for competition and wanted to get some advise on neck diameters.
Norma mic's out around .265" and Lapua is about .273".
So if I run a .265" neck then the Norma gets a slight cleanup and the Lapua gets around .005".
If I did the math correctly then both end up with about .010" neck walls.
Does this seem like a good approach allowing the option to use either case?

Thanks,

K. Hawes
 
To use either Lapua or Norma cases in a 6PPC bench gun, I would get a .265 neck reamer and turn the cases to around .263 or just a little over (depending on the bullet you are using). You could use a .263-.262 reamer fine as well, but of course would need to turn necks around 2 thou under the reamer neck size.
 
You need to measure brass thickness at the neck with a ball mic. Calipers can be used but are not as accurate. Either Lapua or Norma is good. You will need to turn necks with an outside neck turner so your loaded rounds are about .002 less than .265. This would be a brass thickness of .010 plus .243 bullet equals .263 loaded round. You will need a bushing neck die to size the neck properly. A .260 bushing will give you a .002 grip on the bullet.
 
What is your Outside Diameter goal, for load round measurements, with your preferred bullet seated at its pressure ring? Change bullets, and dimensions change.
 
Ok so I measured the outside diameter of the necks at the pressure ring and this is what I got. (Lapua .2725")(Norma .2655")
So with a .265" chamber and .002" neck clearance the Lapua needs .00475" turned off and the Norma needs .00125".
Resultant case necks would be .010" and use .260-259" bushing for .001-.002" neck tension.
The Norma would be a one pass neck turn/cleanup and the Lapua would be more traditional amount with neither having necks supper thin.

Does this seem like a good approach that would allow me to use both sources of brass?
Will the Norma clean up with such a shallow cut? Should I go down to .264"??

Thanks,

K. Hawes
 
I'm confused by some of your statements. Are you reaming or neck turning to achieve the .010 neck thickness?? Both brands will work fine. If the pressure ring gives you .2635 loaded rounds, you may want to cut necks to .0092 to .0095. Since brass thickness varies, a ball mic and an outside neck turner should give you consistent brass.
 
I will be outside neck turning.

Maybe what is confusing is that I don't have the rifle yet, it is currently being built.
I'm trying to decide what neck chamber dimension to use.

Thanks for the response,

K. Hawes
 
Last edited by a moderator:
haweskg said:
Ok so I measured the outside diameter of the necks at the pressure ring and this is what I got. (Lapua .2725")(Norma .2655")
So with a .265" chamber and .002" neck clearance the Lapua needs .00475" turned off and the Norma needs .00125".
Resultant case necks would be .010" and use .260-259" bushing for .001-.002" neck tension.
The Norma would be a one pass neck turn/cleanup and the Lapua would be more traditional amount with neither having necks supper thin.

Does this seem like a good approach that would allow me to use both sources of brass?
Will the Norma clean up with such a shallow cut? Should I go down to .264"??

Thanks,

K. Hawes
Click to expand...

I happen to be one of the old school who doesn't know and doesn't care how much I turn from my necks. The only thing that really counts is what my OD dimension is with a bullet seated in a loaded round in reference to my neck chamber and the amount of clearance I want to achieve.

If my neck chamber was .265" and I wanted .002" of total clearance, I would turn till the loaded round at the pressure ring measured .263". If I wanted .001" of tension, I'd use a .262" bushing. If I wanted .002" of tension, I'd use a 261" bushing, If I wanted .003" I'd use a .260" bushing.

When turning, I turn, seat a bullet in the neck of a dummy round, measure the OD of the neck at the pressure ring, If it meets my requirement I'm done. If it doesn't, I adjust my turner to take off more brass, then turn, and keep progressing until I achieve my goal. If at that point you want to determine how much you turned off go ahead and measure it. Once set, I dedicate my K&M turner for the OD dimension I achieved, and never touch it. To me they're inexpensive enough to have one dedicated to a specific OD for a specific caliber.

Regardless of which brand of brass I was using for my .265" neck chamber size and the desire for .002" of clearance and a loaded round OD of .263", that turner as set up, would achieve it. How much brass did it take off the brand with thicker neck? Who cares? In the end I got the OD dimension I was looking for. The one thing I would do religiously, while progressing, is to measure at least 1 in 10 or 1 in 5 of my dummy rounds at the pressure ring, to make sure nothing had changed mechanically with my turner.
 
haweskg said:
I will be outside neck turning. Maybe what is confusing is that I don't have the rifle yet, it is currently being built. I'm trying to decide what neck chamber dimension to use.
Click to expand...

For a 6PPC, I think you'll find that traditionally more shooters use a .262" neck chamber. Having said that, there are a variety of reamers to choose from. Call Dave Kiff at Pacific Tool and Gauge. He can tell you what he sells the most of these days.
 
haweskg said:
Will the Norma clean up with such a shallow cut? Should I go down to .264"??

Thanks,

K. Hawes
Click to expand...

That is a very good question to ask and since there hasn't been a lot of lots of the new Norma brass yet, the dimensional variation probably hasn't really been determined yet.
I've had quite a few folks ask me why I went with a .271" neck reamer instead of the more popular .269". My answer is simple. I wanted to take the minimum amount of brass off, but I also wanted to clean up the necks entirely no matter what lot of brass I happened to buy. After measuring a bunch of different lots of 220 russian Lapua brass, I found that the biggest variation from fat side to thin side was about .00125". So if I went down to .0125" neck thickness, I'd get consistent neck thickness with every lot and only have to take off the minimum amount of brass.


If it were me, I'd make one reamer for Lapua brass now and then wait a bit and make a reamer for Norma brass later. Then you won't be compromising anything for either kind. Just my thoughts.
 
I originally was going to go with the .269" neck and Lapua but then I found the Norma brass and admittedly the lack of fire forming was attractive.

I read somewhere that the brass stretch is less and more rounds can be fired before annealing with the thicker necks.
I have also read that skim cut necks might not be as accurate as ones with a more substantial cut.
So my thought process was to pick a neck diameter that would allow me to experiment with both approaches while retaining a decent neck thickness.


Thank you all for the good feedback, it's much appreciated.

K. Hawes
 
haweskg said:
I originally was going to go with the .269" neck and Lapua but then I found the Norma brass and admittedly the lack of fire forming was attractive.
Click to expand...

Yes, that is nice. So is the fact that you'll not have a doughnut in the bottom of your neck for at least a very long time. Not that that is a huge deal as we usually don't seat bullets that far down the neck anyway, but it's nice to know your brass necks are a straight cylinder instead of bell-bottomed.

haweskg said:
I read somewhere that the brass stretch is less and more rounds can be fired before annealing with the thicker necks.
I have also read that skim cut necks might not be as accurate as ones with a more substantial cut.
Click to expand...

I too have heard these same things. I've even been told by a veteran shooter that if you're not shooting a .262" neck ppc, you're not shooting a ppc. Well, that pretty much sounded like a dare to me so I quickly decided to make a fat neck ppc. And low and behold, the darn thing shoots just fine! Maybe even better! As for annealing, I don't know because I've never had to anneal a 6ppc brass ever. Fat or thin. That part is determined by the brass metallurgy and how much brass movement there is. If you've got your ducks in a row, you can easily get 80+ firings out of Lapua brass.
As for brass stretch, that part seems to be true although die to chamber fit has much more importance in that equation. But if you're minimally squeezing the brass body with both, I would have to say I've seen less need to trim as often with the fat neck. Must have something to do with the radius and top shoulder diameter being larger. Seems to stop the flow a bit better. I have also noticed this phenomenon in my fat neck and thin necked 6br's (.262" and .269").
 
I have been grinding many many .269 and .263 reamers. It seems like most of my traditional .262 customers are changing to .268 and .269 necks and the elliptical throat. Thanks Dave
 
Since no one is answering, I'll do my best. I'll probably get corrected, but at least we'll have a starting point.

I believe that "elliptical throat" is a throat cut to match the curve of a specific bullet at a specific depth. So, you'd send Dave a dummy loaded round and your throat would exactly match that dummy round.
 
That is correct. Please call for info. Thanks Dave 541-826-5808
 
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