1982 Rem 700 30-06 with custom barrel(hunting rifle). Chamber's neck diameter is .342" verified by both fired case expansion and slugged.

New Lapua cases which measure anywhere from .0015" to .0018" thick in the neck. Tech at Forster says I need to thin my thicker necks 'cause their is too much neck brass being moved around when I try and FL size. Can't seem to get my runout down.

Personally, I'm thinking .0015". Not becuase that's the smallest number I gave but because the numbers work out that way.

15 times 2 = 30. 30 + 3 for clearance + 1 for springback + 308 bullet dia = 342.

Big Al

quote:

Originally posted by GSSP:
1982 Rem 700 30-06 with custom barrel(hunting rifle). Chamber's neck diameter is .342" verified by both fired case expansion and slugged.

New Lapua cases which measure anywhere from .0015" to .0018" thick in the neck. Tech at Forster says I need to thin my thicker necks 'cause their is too much neck brass being moved around when I try and FL size. Can't seem to get my runout down.

Personally, I'm thinking .0015". Not becuase that's the smallest number I gave but because the numbers work out that way.

15 times 2 = 30. 30 + 3 for clearance + 1 for springback + 308 bullet dia = 342.

Big Al

I don't think you are too far off, in spite of (probably) getting your decimal points slightly wrong...

I believe you have neck wall thickness of between .015" and .018" (.0015 - .0018" would be a bit on the thin side, and not allow you any turning at all).

If you figure on turning to .015", that would give you a loaded neck diameter of:
2x0.015 + 0.308 = .338"

And turning to .016" would give you:
2x0.016 + 0.308 = .340"

.002" clearance between loaded round and chamber neck diameter is the MINIMUM you need for safety. However, .002" is really not a lot of clearance for a big game rifle, which presumably must function under adverse conditions - including dust, sand, rain and mud. Under those conditions, a neck clearance of .003 - .004 sounds a tad more reliable. That is what you'd achieve if you turned to .015".

The minimum you can really turn a neck, is probably by removing .001 - .002" - that really amounts to only cleaning up the necks. If you turn as little as that, you will probably get 50-75% of the neck area turned and the remainder untouched. By going to .015" as your target neck wall thickness, you are doing just a tad more than a minimal turn, but if your neck wall thickness measurements are correct, you are still very close to a minimal turn, which is probably what you want.

All in all, if you insist on using Lapua brass in your semi-tight chamber, a turn to .015" would make sense. Otherwise, see if Norma (or RWS) brass might not be thinner, and perhaps avoid turning all together, but still use premium brass. Winchester brass sorted for neck wall variation might work just as well (assuming it is thinner than the Lapua).

- mike

P.S. With regards to your runout problem, are you using a regular (Forster?) FL sizing die with an expander?? If yes, consider either of two options:
1) NS with a Lee Collet die (and use a Redding Body die for FL sizing in a separate sizing step), or
2) let Forster modify your FL sizing die by honing it to a specified inside neck diameter (loaded neck dimeter -.003", say) to be able to use your FL die without the expander. The modification costs $10 plus return shipping.
Either option is usually a good way of getting rid of runout introduced in your sizing operation.

Big Al

Don't take this the wrong way but a .342 chamber in an '06 is pretty much standard and would not be considered a tight or custom neck by most shooters. Turning case necks for an '06 in a hunting grade barrel will probably not result in any increase in accuracy and could make a sloppy chamber even sloppier. If it were mine I would use high quality brass, such as Lapua, leave the necks alone, and strive to get lower runout on loaded rounds with better loading tools and techniques. JMHO

Ray

MHO,

Very well thought return posting. I concurr with your assessment. The Forster tech also mentioned the $10 option of modifying my FL die. Another option; I man whom I have emailed will, for $38, modify my Forster FL die to accept bushings, which I really like as I will probly keep loading 30-06 till I die and that means additional rifles with different sized chamber necks.

Cheechako,

Not taken the wrong way.

It's not the hunting grade chamber I'm worried about. It's trying to get my bullets seated straight. After checking my loading procedures from A to Z, I determined uneven neck thickness was the culprit....so far anyway.

And, my new Win brass only measured 12 to 14 thou thick.

I concurred with the Forster tech that 16-18 thou was a bit thick for new brass.

quote:

Originally posted by GSSP:
MHO,

Very well thought return posting. I concurr with your assessment. The Forster tech also mentioned the $10 option of modifying my FL die. Another option; I man whom I have emailed will, for $38, modify my Forster FL die to accept bushings, which I really like as I will probly keep loading 30-06 till I die and that means additional rifles with different sized chamber necks.

Al, using bushings is a very versatile way of allowing you to adjust your neck tension - by simply changing to a different size bushing.

Jim Carstensen also modifies Redding Body Dies, to be able to use them with bushings - and a lot of people into target shooting seem to be happy with his dies.

That said, in spite of the lack of versatility in a fixed (honed) die, I have often found fixed dies to give me less runout than bushing dies. I know this is a generalization, but I still hold it to be true. So unless I feel I absolutely need the versatility of bushing dies, I prefer fixed dies these days, personal preference, I guess...

This 6mmBR.com Page has articles on both the Jim Carstensen and the Forster die modifications.

In general, I have found that moving the brass a lot (such as necking down a whole bunch, and then wrestling an expander through it for final diameter) is a likely culprit in creating runout. The less your move your brass, the less likely you are to create runout - another generalization, but also one I believe holds true.

In general what Cheechako says is right: don't expect accuracy miracles from turning for a big game rifle. On the other hand, if your measurements of Lapua brass neck wall thickness and your chamber neck diameter are correct, then it certainly sounds like Lapua brass is a bit on the beefy side for your chamber. That is why I suggested trying other brass to see if you might be able to use that unturned. If your Win brass runs between .012 - .014, I'd try different sizing techniques before I got into turning (which is a lot of work for comparatively little return in a big game rifle). If you want to get anal about it, sort your Win brass for neck wall variation, and you will almost have achieved the same as you would with turning.


- mike

P.S. I saw you mentioned using the same FL die for several rifles. That is a touchy subject. Unless you are happy to adjust your FL die every time you change rifles (to assure minimal sizing), it would better to let each rifle have its own FL die, and keep it adjusted for the rifle in question. I'm assuming that if you care about runout, you'll also care about sizing your cases to fit your chamber - quite apart from the safety aspect of possibly sizing your cases too much for one of your rifles with possible case separation looming down the road...

As far as physically possible, depending on the attractiveness and state of undress of the woman in question.

Oh, wait a minute, you mean CASE NECKS! Unfortunately, I have so rarely found a chamber/case combination that was not already excessively loose that I have virtually no experience in turning necks, thus cannot comment.

Now, if you do wish to enquire about turning one's neck to observe attractive women in various states of dress, I have a bit more experience, though not nearly as much as one might desire.

quote:

How far would you turn your necks?

It all depends on how young, how pretty and how she is dressed...

MHO,

Jim Carstensen is who I was referring to.

After your ideas, I feel inclined to continue to agree with you and just take my current Forster FL die and have the $10 hone job to match my current chambers specs.

Then in the future when I have this particular rifle rebarreled to the same 30-06 or a 30-06 AI I will again have Forster hone to the chamber's specs. It's only about $25 for the die and $10 for the hone job.

For the record, I'm not too worried about my brass sitting in the bottom of the chamber, irregardless of how concentric...or not....my brass lines up with the bore. I seat my bullets either touching the lands or about .005" in.

Also, when I sized my .012" to .014" thick Winchester brass, with the decapping assembly removed, I was able to get .0005" or less runout. When I sized my Lapua brass identically, I would get .002" runout. Thus my search into finding out just how thick my Lapua brass was and determing that the thick necks were ruining the runout numbers.

Also, I realize I need to fire the Lapua brass before I run anymore runout tests.

Big Al

If the neck thickness your Lapua cases really does vary from 0.015†to 0.018â€, then I would say that for safety’s sake alone, you MUST turn them. (it does sound to me like a very large variance, especially for Lapua brass, which is generally noted for being of good uniformity)

With the thickest cases, you will have loaded cartridges with a neck diameter of 0.344†(0.308 + 2x0.018 = 0.344) in other words, 0.002†LARGER than your chamber neck. This is not good – to put it mildly!!! I doubt that I need to spell out all the possible consequences of having some cases of this neck dimension mixed in with others which – mostly – provide a few thou of neck clearance.

quote:

Originally posted by redrover:
Big Al

If the neck thickness your Lapua cases really does vary from 0.015†to 0.018â€, then I would say that for safety’s sake alone, you MUST turn them. (it does sound to me like a very large variance, especially for Lapua brass, which is generally noted for being of good uniformity)

I assumed he meant that the neck thickness on individual cases varied from .015 to .018, not that some measured .015 and others measured .018. Either way that does seem like an awful lot of variance for Lapua brass. If true I think I'd contact the dealer of that brass and ask for a refund rather than turning them. JMHO

Ray.

I would throw that brass away and buy some that is within normal specs. If my new brass makes cockeyed loads I would get new dies. IF my chamber was really too tight I would send the rifle back to the manufacturer for repair. See where I am going here? It is a hunting rifle not a bench rifle.

If you have time for this kind of fiddling around, you are very lucky. To be truthfull, I am a bit jealous. Let s be real though, you should be able to shoot your 30-06 with Kmart ammo. Neck turning????

Got a problem. In doing the math, it all works out fine. But in practice.....not!

I took several cases and mic'd their wall thickness', mic'd some Nosler 180 BT diameters and then measured the seated rounds. The math is not coming out.

Example:

.015" thick neck x 2 =.030" + .308 bullet did not come to .338". Instead it came to .3357" (measured via a Starett 1" micrometer). That is .0023" difference. What gives? Does the brass stretch thinner when seated around a bullet?

I've checked all my measuring tools against items of known thickness'.

Al, how do you measure neck wall thickness?? A ball micrometer is the accepted method, but a lot of people believe the only real way of measuring it consistently is to measure loaded round neck diameter.

No, I don't think the neck walls "stretch" when seating a bullet.

The good news is that if your loaded necks turn out thinner than what you had imagined, then you should be fine with a no-turn use in your .342 chamber. That would leave only the issue of runout with the Lapua brass, and I believe you should be able to get a handle on that by using different sizing method(s).

Btw, just yesterday I happened to measure some loaded .30-06 ammo in preparation for a Forster die modification (see, you are not the only one ). With unturned Lapua brass, I had an average loaded neck diameter of .3353" (over 2 cases measured with a pair of Starret calipers). That is awfully close to the measurements you get - with my calipers, I can't measure reliably in the .0001 range. If this measurement holds up with Lapua brass, then Cheechako's statement of .342 chamber neck not being tight looks very correct.

Again, this points to you being able to use Lapua unturned, which would be a huge advantage. If you end up finding Lapua brass does not deliver on its promise of "premium" brass, go back to your Win or try Norma or RWS, say.

- mike

Don't know about you, or the others on here.

But, mine turns just less than 180%. Not quite as far one way as the other, but, close.

haha, smile damn it!!

George

Mike,

I have a Sinclair Mic-4 neck gage. I 1st make sure the RCBS pilot is set so when the case to be meaaured is in position, I'm measuring about 1/16th" from the mouth. I then make sure the dial caliber is zero'd, with EACH new case. I then insure the case has been 1) sized and 2) totally clean and free of all residue inside the neck. Once the case is in place, I'll use one of several methods to insure I'm not getting erroneous readings.

I'm always holding the gage in my left hand, making sure i've got good light that makes it easy for me to see the gage and does not throw any shadows on the dial, giving me a false reading.

1. I'll barely turn the vertically placed case and let go of the case to get the reading. Repeat, read, repeat, read; noting the readings all the way around the case as I turn it several times.

2. Or, I may just VERY slowly turn the case, again in a vertical position, watching the dial indicator for highs and lows.

Even though this dial indicator reads to .001", it's no chore to read to at least 1/4th that.

Is that the information you are looking for?

Here is a dilema. I had measured all the cases and placed them in groups.

6 cases = .0005" or less variation
38 cases = .006 to .001" variation
29 cases = .0011 to .0015" variation
16 cases = .0016 to .002 variation
11 cases = .0021 or more

I've already turned the highest 50 to .0015".

Now, I can continue on turning the remaining 50 or leave well enough alone and lick my wounds. My older Win cases are aleady at a max of .0014" so trimming all the Lapua to .0015" should not be too bad......?

The good news is those 50 "worst" cases have no more than .001 neck wall thickness variation, with most running .0005 to .00075.

quote:

Reply

A dial calaper is no way to get an accurate neck thickness reading.