Neck turning in one pass

S

skeetlee

Active member
I had a conversation with a fella today, and we were discussing neck turning. The idea was brought up that neck turning a .262 neck and cutting the brass all off in one pass of the cutter, or one cycle of the cutter, might introduce unwanted run out into the brass. His theory was that cutting to much brass at one time might actually twist the case causing run out. This has me thinking. I dont have a run out tool, as i didnt find the one i had very useful, so i sold it and bought bullets. Much more useful at the time. I have shot loaded rounds with bullet run out as much as .005, and they still shot little bitty groups. Anyway does anyone else think that cutting a .262 neck with one cycle of a neck turning tool, " cycle meaning down the neck and back up" can cause run out? I do expect that necking up from 220 Russian to 6mm will cause some run out, that probably to be expected. I havent turned a lot of cases, but i have been using a 21st century tool of my buddies, and that cutter seems to cut really well doing it all with one pass. That tool has a carbide cutter, but i dont know that means much as brass is a soft metal anyway. The cutter seems to do a great job.
We also discussed, that even after firing a ppc case with the run out caused from neck turning, that the case will not straighten itself. I always thought it probably would be straight after being hammered at 60,000 psi?? Any thoughts? I just find this type of discussion interesting. lee
 
Lee,
It seems to me that in order for a useful discussion about to take place, you need to reacquire a concentricity gauge. People use all sorts of methods, most of us would rather have straight brass, even is there is some doubt as to it always giving better results. IMO if you are getting a loaded round of .0015 or better, about .150 in front of the case neck, you have little to gain. I think that if you do not have too much bullet in the neck, the necks are relatively thin, and bullets are seated into the rifling, that closing the bolt on a loaded round tends to straighten the round. IMO, given clearances on a loaded round, in a typical benchrest chamber, there is no way for it to stay as crooked as what you mentioned testing, once it is fully chambered. I have purposely made crooked ammo, chambered it, and remeasured it, and it went from .0036 or so runout, to about .0015 or less. That was with the neck clearance that I used to run. With the more generous clearance that I have recently adopted, I think that the degree of straightening that is available from chambering a round may be decreased.
Boyd
 
I have done one pass. WE might be comparing apple and oranges.
I used a Sinclair cutter and their expander arbors. Expander was chucked up in a lathe.
Cutter was placed in a vise of Bridgeport Mill. Cool Tool was also used.
Cooling the brass might be the key. :cool:
 
Boyd
I might try and make one, but i dont think i will spend the money on another any time soon. As savoy as most of us here are, i was hoping someone else has already checked the effects of cutting brass in one pass or multiple passes. There are more than a couple fellas here who if they would tell me, yes cutting to much brass at one time can cause excessive case run out, then i would believe it, and start cutting my brass in two passes. If we dont think there is any ill effect in cutting all the brass in one pass, then i will just continue as i have been.
as you know i like to test certain ideas myself, but in this case i am just looking for opinions or known experiences. The boards have been a bit slow here lately and i thought this might be good conversation? To be perfectly honest, my targets look decent so i am not really all that concerned. Curious? For sure! Lee
 
Boyd,

In my experience, more barrels than you might think prefer the bullet to be seated with a jump. Up to .020 with typical PPC ogives, and up to .040 (or maybe more, but that can cause other problems) with the more radical ogives of long-range bullets.

Now you say, "ah, but I lose the straightening effect I get by jamming the bullet." Perhaps you do. So one should accept what may be a less than ideal situation because you can't be bothered to fix something worse? Not me. This is not a compromise one has to make.

Edit:

I was pleased to see Gene Beggs, in the tunnel, had a similar observation:

Most of my shooting during the past several years has been in the wind free environment of the tunnel. One thing that continues to repeat with every gun, barrel and bullet combination I have worked with is that horizontal dispersion results from the bullets being seated too far into the lands and vertical dispersion is the result of the powder charge being either too hot or too light.

Daryl Loker told me years ago that you tune out the horizontal with neck tension and bullet seating depth, then tune the vertical out with the load. (Or in recent years since the advent of tuners, with the tuner.)

I assure you, if I put my standard load of powder in and seat the bullets on hard jam, I'll have two bullet holes of built in horizontal, and that's in a tunnel with no wind! Start pushing the bullets back into the case .005 at a time and the horizontal will disappear just when the bullets come off the lands or just kissing. You might as well keep this to yourself after you see it with your own eyes because no one will believe you if you try to tell them; it goes completely against conventional wisdom. :rolleyes:

Gene Beggs
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skeetlee said:
Boyd
I might try and make one, but i dont think i will spend the money on another any time soon. As savoy as most of us here are, i was hoping someone else has already checked the effects of cutting brass in one pass or multiple passes. There are more than a couple fellas here who if they would tell me, yes cutting to much brass at one time can cause excessive case run out, then i would believe it, and start cutting my brass in two passes. If we dont think there is any ill effect in cutting all the brass in one pass, then i will just continue as i have been.
as you know i like to test certain ideas myself, but in this case i am just looking for opinions or known experiences. The boards have been a bit slow here lately and i thought this might be good conversation? To be perfectly honest, my targets look decent so i am not really all that concerned. Curious? For sure! Lee
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Lee,

Curiosity is a good thing, it tends to spawn experiments, that in turn spawn things like the 6mm PPC, which began with "What if we tried this".

Dick
 
when you turn your case necks, measure with your ball mic in spots all the way around your case necks and see what you read..dont just measure four spots around the neck but eight spots around the neck and see what you read..I think if your reading .0005 that is too much..I think it's hard to hold .0001-.0003. I use the 21st century for rough cutting. i can not hold as tight a tolerance with the 21st century turner as i can with the k&m turner. at leat not in the hundered or so cases i turned with it. best i could get from it was .0005, i switched back to the good old k&m.
 
I think my other post in this thread is far more important, but

I had a conversation with a fella today, and we were discussing neck turning. The idea was brought up that neck turning a .262 neck and cutting the brass all off in one pass of the cutter, or one cycle of the cutter, might introduce unwanted run out into the brass. His theory was that cutting to much brass at one time might actually twist the case causing run out.
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Well, maybe you can find a way to cause distortion, but it is just as easy to not do it. Jackie Schmidt turned all his necks on a lathe, one cycle only, hand fed up to the shoulder, then machine fed backing off. As with doing so many things well, Jackie is noted for having quite true rounds.

Unless you have some bizarre rituals with your neck turning, I think you'll find the runout comes from other places.

Finally, TJ Jackson proved to his (and my) satisfaction that if the case neck is true to the bore, and the base perpendicular to the boltface, not much else in the case matters. Far as I'm concerned, so much for the case, the rest is in the dies.
 
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Charles,
I am not against jumping, I was just pointing out that if you are, you have one situation, as far as straightening by chambering a round, and if you are not, another. As far as turning necks with a lathe goes, the forces on the case are entirely different from turning them with a more "normal" tool. On the lathe the case is forced onto the mandrel, and it is that fit that drives the case. The case and the mandrel turn together. Whereas in the case of a neck turner. the neck is driven by its rim, and turns on the mandrel. I think that these sort of experiments are best done by the shooter with the question, because depending on the width of the cut, rpm, and rate of feed down the neck, there can be considerable difference in outcome. I have done it both ways, but prefer two cuts. A friend has told me that when he turned in one pass, the necks were more crooked than if he takes two cuts. If I am doing it in one, I slow the process and seem to get satisfactory results. The reason that I now do two is that they are at different stages, in the fire forming process, and are done at different diameters.
Boyd
 
If I am doing it in one, I slow the process and seem to get satisfactory results. The reason that I now do two is that they are at different stages, in the fire forming process, and are done at different diameters.
Boyd
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Sort of points out the problem with the original post. For that record nobody's keeping, I turn necks twice, too, but I don't change the cutter position.

I turn the necks by hand, not using power. I use carbide mandrels. Heat is not an issue. You can feel the inside of the neck this way, and might be amazed to discover just how many cases have a thin spot on the inside, most of the length of the neck. Not that I'm at all convinced this matters...

If I'm really doing a bang-up job -- say, making a set of cases for the Nationals when both me & the guns are shooting good & I think I got a chance, I'll die-form them, turn the necks, fireform, ANNEAL, then turn the necks again, with the cutter at the same setting. Then fireform again.

Boring the necks true is another good notion, but takes a very good lathe & collet setup. I use one wildcat where I made a die using the resize reamer, so the case won't turn in the die. It is a one-piece die, and in the top we have a ground & hardened pilot bushing, the kind usually used for a drill. Instead of the drill, I used a chucking reamer. Unless you've a tool-room lathe, that's the best way I've found to get the inside of the neck on the bore centerline. If anyone can think of a better one, I'm all ears.

I'll allow that's too much work for a sane person, and that the improvement is trumped by missing a half-a-mile change in the wind, or for long range, not measuring/checking bullets carefully, esp. the base.

As far as turning necks goes, I'm sure there are any number of techniques that will give success, and probably just about as many that will give less than ideal results. It's like so much you want to discuss Skeet, it's the wrong level, far to general, to ask a useful question.
 
Lee,

I turn around 400-500 pieces of brass a year. That's 6ppc with .262 & .268 nks and the 22-.100 short. All of it is turned in one pass and I've done it that way since around 2005. If you have a sharp cutter and anything but an idiot technique, you'll never notice the difference. I do recommend the carbide cutter and carbide mandrel.

Never heard of inducing twist/runout to brass neck turning. Also, none of this brass is straight until it's fireformed twice. Heck, you know how crooked 22ppc short brass is after it is formed. Now I won't shoot it in competition until it's been fired three times to just be safe but most of the time it has .020-.030 of runout/wobble before the first firing.

Hovis
 
You can't make your rifle shoot better using any method of neck turning. We bought into reduced neck diameters requiring that we turn necks to have clearance - and clearance is all we need. "Perfect" clearance is OK too but totally unnecessary.

Again for effect....You can't make your rifle shoot better using any method of neck turning.
 
I'm a two-pass guy..............well, I used to be anyways, when I was shooting .262" necks. Now that I've gone to the .271" neck, it's one light pass and done.:cool:


I use(d) steel mandrels. Here's why:

You need to have a certain dimensional relationship between your expander and your mandrel. If it's too close, the case is too tight and will heat up very quickly. If it's too loose, your cut is not uniform. You buy an expander and it comes at .xxxx" size. Then you buy a mandrel (either carbide or steel) and it comes at .xxxx" size. If you're lucky, the $60 carbide mandrel will have the right dimension. But, most often, it wil not. If the steel mandrel doesn't have the right dimension, no problem, you can sand it down until it does. And you only paid $8 for it. So, you can get a custom fit for less with steel. The downside to steel is that it must be lubricated, must be cleaned religiously, must be cooled, and it tends to embed chips that will thread the inside of your necks. Because of these things, I found my results were always better to cut necks in two passes than with one.

Now, I know some folks are going to say that the best way is to buy the carbide mandrel and then buy several expanders and pick the one that has the best size for your mandrel. That is a good way to do it, no doubt, but you're still playing musical chairs and buying lots of un-needed things. I just found it easier to buy one expander and one mandrel and fit them. But if you have lot of $$$, don't worry about buying things you'll never need again.
 
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When I have turned in two steps, both at 6mm, I did the first cut to within .001 of my final thickness, with an old Sinclair turner, after using a K&M expander, that leaves the necks a little looser than I might want for a final cut. With the loose fit, and my normal lubrication, there is no heating or brassing of the steel mandrel. Because it is a rough cut, I am not concerned that it might not be perfect. The finish cut will clean up any problems. After the rough cut, necks do not fit the carbide K&M mandrel as tightly as unturned brass. This reduces heating. Dwell time on expander is also a variable, as well as delay between expanding and turning. If you leave the neck on the expander for a couple of seconds, the fit on the turning mandrel will be slightly less tight than if you quickly run the mandrel in and out of the neck. If you expand all of your brass, and do not get around to turning it all that day, you will find that its fit on the turning mandrel is tighter the next day.
 
Excellent post Charles (G. Beggs testimony) post #5 and my findings too... Plus a LIGHT seat or jump gives one the option of opening the bolt to cool the throat AND not induce heat in the next round while waiting for a condition / cease fire....
Pulling a bullet outta the case and dumping powder during a match SUCKS, been ther dun it...!
Now if the barrel ONLY shoots with a stiff jam...... Then there it is.... Now, every cut barrel 4 groove I have had over the last 10 years has "been friendly" to a little jump of some sort...

The above is 100/200 Benchrest.... Now long range stuff and in particular Secant ogives... Jam is mostly the way... Have you seen this Charles..?

Getting back to topic, I can't help but to agree with Wilbur... But I do two pass cut my .262 nks.. They turn out VERY consistent in thickness, now concentrics.... Mostly >Strait chamber and dies... Well, best I can find... .0015 +- .0005 run out typically with fully fireformed rounds and checking the runout with bullet in the neck...

Reading wind and Tune IS the way:p........... Mouth FULL there:eek:...!

cale
 
The above is 100/200 Benchrest.... Now long range stuff and in particular Secant ogives... Jam is mostly the way... Have you seen this Charles..?
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Uh, no, mostly from friends who shoot secant ogives. In .30 and 6mm, I'm pretty wedded to BIBs, which are always high-number tangents. Some barrels liked a jam, some a jump, but I've been lucky that all the barrels seemed to like them one way or another.

With the 6.5s, I pretty much used Sierra and Clinch Rivers. The latter were a secant (but not 15-caliber), and I did jam them. With the new .338 & 300-grain Berger hybrids, I'm finding a small jump best in my current barrel.

* * *

During the last half of the 1990s, I watched Berger, the primary supplier of 15-caliber secant ogive bullets (aka VLDs), go from recommending a jump to a jam. Charles Bailey, one of the best shooters that's been down the pike -- he had his own range, and tested everything as well as being an excellent machinist -- determined that .020 off worked best with his barrels. He checked this with every lot -- this was during the time Walt had sold the company, and variation was common -- but always got the best groups with around .020 off in his .300 Ackley.

(Edit: Sorry, that's Berger 30 caliber 210 VLDs. IIRC, CB's sort ratio, of the bullets of that time, were about equal part "A" grade, "B" grade, and "not" grade. There is another story about how he finally got SOTY using the "B" grade bullets, but...that's another story.)

Well, this is one story, not data, but I hope it makes the point that you should always check. It doesn't take than many extra rounds.

Edit:

Wilbur said:
You can't make your rifle shoot better using any method of neck turning. We bought into reduced neck diameters requiring that we turn necks to have clearance - and clearance is all we need. "Perfect" clearance is OK too but totally unnecessary.

Again for effect....You can't make your rifle shoot better using any method of neck turning.
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You know Wilbur, I disagree with that. We got into neck turning because back in the days of the .222, some guys were extracting a loaded round & saw marks on one side of the bullet, but not the other.

OK, that's pretty gross misalignment. However, I believe the guys who say they can see the difference between groups, the group will be smaller if the rounds have less runout, when shot in a tunnel. All the while allowing that if it's such a small factor it takes a tunnel to see it, it's gotta be pretty far down on the list.

Here's the problem: You aren't the first experienced old-timer to discover than a lot of what we do "doesn't matter on paper." Pretty soon you get to the point that nothing matters, it's all magic

To each his own, but I'm not going there.
 
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yea it's all magic..i was at the range with my old 6BR and it's old wore out magic barrel. had some varmint bullets loaded up for it. well had my new 6BR with some top grade match loads loaded for it..well it was shooting ok just trying to see flag changes.. i was letting the barrel cool..so set up the old 6BR and started shooting, one, next one same hole,next one same hole,and so on when i realized i was shooting the top grade match ammo that i loaded for the other rifle..hun..it just does not matter what ya shoot in it i guess.all i can say is the new one dont shoot like that..and that's at 1,800 rounds.. well for that reason i'm never taken the 6ppc and the BR to the range at the same time..I really was shocked that i was pulling the wrong ammo and shooting them..only about .001 difference in the neck's.. It seems i can switch between them and it really does not matter much. I shoot for the .003 clearance i think it allows for slightly hotter load. but i end up with .0025 and it works for me.
 
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