Neck Turning Question

[Cincinnatus]

German Salazar wrote a great article entitled "Neck Turning Basics" that appeared in the technical article section. I understand most of it, but there is something that confuses me. In the paragraph entitled "Brass Preparation", Mr. Salazar directs the reader to resize the brass with a full-length non-bushing die. I get the reason for that, it is to make the neck more uniform in preparation for turning the neck.

Where I get lost is in the next paragraph, entitled "Expander". I don't know if the expander that Mr. Salazar now directs the reader to use is something different from the expander ball of the full-length sizing die just used, or is something different. It appears to be something different, a K & M expander.

But my question is why? What is the purpose of using the K & M expander at this point, when the neck of the case has, presumably, been properly expanded by the expander ball of the full-length sizer die?

If anyone, especially Mr. Salazar, can shed light on this, I would appreciate it.

 

[SierraCJ5]

When turning necks you need to expand necks with a mandrel sized properly to maintain correct neck clearance on the turning mandrel. Typically you should use the same brand expander as turning mandrel since they're engineered together. Hope this helps.

 

[divingin]

What is the purpose of using the K & M expander at this point, when the neck of the case has, presumably, been properly expanded by the expander ball of the full-length sizer die?

The K&M expander is slightly larger than a normal expander ball/button. It's designed so you get a snug(ish) fit of the brass on the expander mandrel, but not so tight that it tends to bind and gall (as it would straight from resizing.)

 

[spife7980]

For neck turning you will size down as you stated and then open them back up to the correct diameter. An expanding mandrel is .001 under the cartridge diameter and the turning mandrel is .002 under. By expanding first you make it a nice tight fit on the turning mandrel so that you dont have any play in the neck while turning the material off.

And as a bonus you can then use the turning mandrel to set the neck tension for reloading. I do this last step myself without turning.

 

[muleman69]

For neck turning you will size down as you stated and then open them back up to the correct diameter. An expanding mandrel is .001 under the cartridge diameter and the turning mandrel is .002 under. By expanding first you make it a nice tight fit on the turning mandrel so that you dont have any play in the neck while turning the material off.

And as a bonus you can then use the turning mandrel to set the neck tension for reloading. I do this last step myself without turning.

Why would they not just make a turning mandrel .002 smaller than resize button/ball? Also like to no how you go about using turning mandrel to set neck tension?

 

[Willie]

Why would they not just make a turning mandrel .002 smaller than resize button/ball? Also like to no how you go about using turning mandrel to set neck tension?

The expander mandrel for turning is not to be confused with those used to set neck tension. For example, I size my necks down approximately .003" from a loaded round diameter, I then use a .002" under caliber mandrel to open the neck to have an approximate .002" interference fit (neck tension, if you wish). K&M makes a variety of mandrels for most calibers. It's late, hope this makes sense.

 

[spife7980]

Why would they not just make a turning mandrel .002 smaller than resize button/ball?

Why? I guess you could get one at that dimension but thats not the standard and I dont get why one would do so. The standard is expanding mandrel is .001 less than bullet diameter and turning is .002 less. I presume so that it matches what it would be when wrapped around the bullet.

Also like to no how you go about using turning mandrel to set neck tension?

You put it in your expanding die and push it into the sized down case necks to open them back up. You use it instead of the expander ball.

 

[muleman69]

The expander mandrel for turning is not to be confused with those used to set neck tension. For example, I size my necks down approximately .003" from a loaded round diameter, I then use a .002" under caliber mandrel to open the neck to have an approximate .002" interference fit (neck tension, if you wish). K&M makes a variety of mandrels for most calibers. It's late, hope this makes sense.

Couldn't I buy a bushing die that was .001 under loaded round and get the same results? Welcome home Wille,I was in the north around the same time 1st marines

 

[muleman69]

Why? I guess you could get one at that dimension but thats not the standard and I dont get why one would do so. The standard is expanding mandrel is .001 less than bullet diameter and turning is .002 less. I presume so that it matches what it would be when wrapped around the bullet.



You put it in your expanding die and push it into the sized down case necks to open them back up. You use it instead of the expander ball.

Thanks,very informative. I'm a bit slow but think I'm getting it

 

[spife7980]

Thanks,very informative. I'm a bit slow but think I'm getting it

Allow me to expand a bitmore then:

The full length die squeezes it down small, typically the expander ball would be dragged back through the down sized necks to open the necks back up to the proper internal diameter all in the same stroke for loading in the vast majority of resizing scenarios for most people.

But turning necks isnt for most people out there. For turning the necks you want it as absolutely dead nuts straight as possible. To do that you replace the expander ball with these mandrels in a separate step which will limit any concentricy problems when you force it down inside the sized down case neck. By first using the expander mandrel you widen the mouth to .001 under bullet diameter which allows for the tight slip fit over the turning mandrel which is only .001 smaller than the expander mandrel (thats .002 smaller than bullet diameter and why lubing the mandrel is important, the tight fit creates friction). Shoving this mandrel in the neck will make a uniform internal diameter and push the discrepancies in the brass neck thickness to the outside where they can be trimmed off by the cutter leaving the neck thicknesses as uniform as possible.

Now... even if you arent turning your necks you can still make use of the mandrels to open the necks back up to set bullets into to take advantage of the accuracy and concentrical benefits (minimizing run out). As most people want .002" of interference fit between the bullet and the brass the turning mandrel is the one they use for this step more often than not.

 

[muleman69]

Allow me to expand a bitmore then:

The full length die squeezes it down small, typically the expander ball would be dragged back through the down sized necks to open the necks back up to the proper internal diameter all in the same stroke for loading in the vast majority of resizing scenarios for most people.

But turning necks isnt for most people out there. For turning the necks you want it as absolutely dead nuts straight as possible. To do that you replace the expander ball with these mandrels in a separate step which will limit any concentricy problems when you force it down inside the sized down case neck. By first using the expander mandrel you widen the mouth to .001 under bullet diameter which allows for the tight slip fit over the turning mandrel which is only .001 smaller than the expander mandrel (thats .002 smaller than bullet diameter and why lubing the mandrel is important, the tight fit creates friction). Shoving this mandrel in the neck will make a uniform internal diameter and push the discrepancies in the brass neck thickness to the outside where they can be trimmed off by the cutter leaving the neck thicknesses as uniform as possible.

Now... even if you arent turning your necks you can still make use of the mandrels to open the necks back up to set bullets into to take advantage of the accuracy and concentrical benefits (minimizing run out). As most people want .002" of interference fit between the bullet and the brass the turning mandrel is the one they use for this step more often than not.

I'm getting it now, I don't have a .30 cal expander so I resized then seated a bullet then pulled the bullet and then turned the necks, worked well.Shot a .237 group today with it in the snow. Poor people have poor ways they say. .....LOL Thank you

 

[ShootDots]

I think the main aspect of neck turning has been missed here. Everyone's explanation here is valuable and is true. BUT here is the underlying reason for neck turning. When you get new / "virgin" brass, no matter the manufacturer, the neck has heavy sides and lighter sides of "wall thickness" all around the neck. By running an EXPANDER mandrel into the case mouth and down the length of the case neck, you are pushing those "imperfections" from the INSIDE of the case neck wall to the OUTSIDE of the case neck wall. Now that the imperfections are on the outside, you can turn those imperfections OFF and you will have concentric necks and consistent neck wall thicknesses all the way around the neck.
ADDITIONALLY, it has been MY experience that, especially for many competitive disciplines, turning the neck wall thickness down to 12 thousandths, along with annealing, will allow for "smooth as butter" bullet seating.
I hope this helps in your understanding..

NOTE: here is a little trick: When you run a case up into the expander mandrel you will notice it takes a bit of force the first time. NOW, lower the press arm to withdraw the case and turn the case 1/4 turn and run it back up into the mandrel. You will notice that it now goes up in there easier. Repeat this procedure 3-4 times and you will notice that the mandrel now goes in pretty easy. This takes all of about an extra 5 seconds to perform. Why this is important is that NOW you can actually FEEL that those imperfections have in fact been PUSHED to the outside of the case neck wall in order to be turned off by the neck turner.

 

[243winxb]

What is the purpose of using the K & M expander at this point

The expander is inside the neck while turning and is larger in diameter than the dies expander. No spring back of the brass while turning. Never used one.

My Lyman uses FL sized brass from a standard die. The pilot has slop, but the pinch point removes it while cutting. Brass is wedged between the cutter and pilot.

 

[Cincinnatus]

Gentlemen:

I want to thank you for your informative replies to my original question. I will consider them carefully.

 

[muleman69]

I think the main aspect of neck turning has been missed here. Everyone's explanation here is valuable and is true. BUT here is the underlying reason for neck turning. When you get new / "virgin" brass, no matter the manufacturer, the neck has heavy sides and lighter sides of "wall thickness" all around the neck. By running an EXPANDER mandrel into the case mouth and down the length of the case neck, you are pushing those "imperfections" from the INSIDE of the case neck wall to the OUTSIDE of the case neck wall. Now that the imperfections are on the outside, you can turn those imperfections OFF and you will have concentric necks and consistent neck wall thicknesses all the way around the neck.
ADDITIONALLY, it has been MY experience that, especially for many competitive disciplines, turning the neck wall thickness down to 12 thousandths, along with annealing, will allow for "smooth as butter" bullet seating.
I hope this helps in your understanding..

NOTE: here is a little trick: When you run a case up into the expander mandrel you will notice it takes a bit of force the first time. NOW, lower the press arm to withdraw the case and turn the case 1/4 turn and run it back up into the mandrel. You will notice that it now goes up in there easier. Repeat this procedure 3-4 times and you will notice that the mandrel now goes in pretty easy. This takes all of about an extra 5 seconds to perform. Why this is important is that NOW you can actually FEEL that those imperfections have in fact been PUSHED to the outside of the case neck wall in order to be turned off by the neck turner.

SO IS 12 THOUSAND ABOUT A NORM? What would be a safe minimum?

 

[spife7980]

SO IS 12 THOUSAND ABOUT A NORM? What would be a safe minimum?

There is no way to answer that without knowing the caliber and neck diameter of the particular chamber. .012 might be perfect for one but way under or over for something else.

 

[Mozella]

Couldn't I buy a bushing die that was .001 under loaded round and get the same results? ....... snip............

Nope; Here's why.

The idea is to have the neck fit on the turning mandrel with just enough clearance so that it doesn't overheat but not so much that it wobbles around. If you use an external sizing die to try to set the ID of the case, your results will vary depending on the neck thickness. Plus you're assuming that your neck thickness isn't consistent from side to side and may or may not be consistent from case to case. That's why you're neck turning in the first place. You're trying to make all your cases the same and make the OD of the neck concentric with the ID.

You size the neck with a bushing die to be a little small to start with. Then, by using an expanding mandrel made by the same company who makes your turning mandrel, you expand the neck with the expanding mandrel to just right ID to fit over the turning mandrel, assuming some sort of "normal" spring back, whatever "normal" is.

Skipping the expanding mandrel step will lead to disappointment.

These mandrels cost only a few bucks each.

 

[ShootDots]

SO IS 12 THOUSAND ABOUT A NORM? What would be a safe minimum?

I order ALL my reamers with a neck diameter that FORCES me to turn my necks to 12 thousandths. EXAMPLE: My "straight" .284 reamer has a .313 neck and a .235 Freebore. Lapua 6.5 x .284 brass has between 14-15 thousandths neck wall thickness from the factory. If left alone, I simply could not chamber a loaded round. However, once I turn my necks to 12 thousandths, I end up with 4 thousandths neck wall / chamber wall clearance. Now that the neck walls are 12 thousandths AND I anneal, my bullet seating is absolutely butter smooth every time.
Now for "SAFE" minimums, that is a personal preference. Some of your BEST Benchrest shooters turn their necks down to 9 thousandths! This entails making sure you have the proper reamer for that "thinness", if you will. Additionally, neck tension(s) for the absolute best accuracy will be not only very critical for accuracy, it may actually entail a HEAVIER tension to properly hold that bullet straight and in place. Much of this "what's the best" argument is really based on the shooting discipline you are engaging in>>>not necessarily what is "BEST" for your use!

 

[Hanbleceya]

I think the main aspect of neck turning has been missed here. Everyone's explanation here is valuable and is true. BUT here is the underlying reason for neck turning. When you get new / "virgin" brass, no matter the manufacturer, the neck has heavy sides and lighter sides of "wall thickness" all around the neck. By running an EXPANDER mandrel into the case mouth and down the length of the case neck, you are pushing those "imperfections" from the INSIDE of the case neck wall to the OUTSIDE of the case neck wall. Now that the imperfections are on the outside, you can turn those imperfections OFF and you will have concentric necks and consistent neck wall thicknesses all the way around the neck.
ADDITIONALLY, it has been MY experience that, especially for many competitive disciplines, turning the neck wall thickness down to 12 thousandths, along with annealing, will allow for "smooth as butter" bullet seating.
I hope this helps in your understanding..

NOTE: here is a little trick: When you run a case up into the expander mandrel you will notice it takes a bit of force the first time. NOW, lower the press arm to withdraw the case and turn the case 1/4 turn and run it back up into the mandrel. You will notice that it now goes up in there easier. Repeat this procedure 3-4 times and you will notice that the mandrel now goes in pretty easy. This takes all of about an extra 5 seconds to perform. Why this is important is that NOW you can actually FEEL that those imperfections have in fact been PUSHED to the outside of the case neck wall in order to be turned off by the neck turner.

"withdraw the case and turn the case 1/4 turn and run it back up into the mandrel." Made measurable difference for me. Would add that beyond feeling the difference on the second stroke, you are pressing outward from two different segments of the radius. That can't hurt

 

[Hanbleceya]

Thanks,very informative. I'm a bit slow but think I'm getting it

side note: bushing dies do not reach the bottom of the neck, hence will have a bulge