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Which expander mandrel are you using?
- Thread starter mkelly
- Start date
I’ve been using a Sinclair carbide turn mandrel with good results, no issues with galling on the mandrel. I’m going to try a k&m shortly due to having to neck turn and want to match the turner pilot.
Really its a k&m vs 21st/sinclair/pma as all three of those are compatible with each other.
I have a 21st body and use 21st and sinclair mandrels equally.
I have a 21st body and use 21st and sinclair mandrels equally.
I use Sinclair carbide turning mandrels, but also have 21st Century TiN mandrels.
The new black nitride mandrel from 21st Century looks very promising, they claim "Hard as carbide, slick as graphite". At $28.50 for a mandrel I'd give it some serious consideration.
The new black nitride mandrel from 21st Century looks very promising, they claim "Hard as carbide, slick as graphite". At $28.50 for a mandrel I'd give it some serious consideration.
I ordered a couple this morning. I will report back with results.
I have become a big fan of the new expander mandrel in Black nitride. Smooth as butter. Now the big question is for how long.
Like @spife7980 mentioned, just pick a brand. Sinclair (et al) are made with a 1/2" diameter base, and IIRC, the K&M are 3/8" diameter base. Both do the same thing, but (obviously) mandrels are not interchangeable.
I had used a Wilson expander mandrel for 6.5 CM and recently acquired a 21st Century expander in black nitride. The difference in force was an eye opener. I dip the necks in Redding dry neck lube and then run them through the expander. Amazing how smooth the 21st Century black nitride mandrel was. Like a hot knife through butter.
21st Century Black Nitride Turning Arbor.
Why? Because the price was right and other people use it
Why? Because the price was right and other people use it
I'm using a Sinclair expander body w/ their carbide mandrels and I have zero complaint. Pretty sure it accepts 21st century mandrels as well. Someone correct me if I'm wrong. Not gonna lie, I was gonna get a 21st century like ^^ everyone here, but I was able to get Sinclair faster.
Sinclair carbide mandrels on the way. The Sinclair expander die I need is OOS so I went with PMA for the die.
What was the reasoning? And were you talking about the expander mandrel or the turning arbor? Expander gives 0.001” of tension and turning arbor gives 0.002” tension, I believe, so if you were talking about getting the expander mandrel, he might’ve warned you that most find that to be insufficient neck tension?
I specifically was going to order this: https://21stcenturyinnovation.com/buy-online/ols/products/black-nitride-expander-mandrel/v/NBE26
He stopped me to ask what my plan is. I told him I wanted to use it for neck tension for seating bullets. He said, Won't work. Don't order that. and told me to order this: https://21stcenturyinnovation.com/buy-online/ols/products/caliber-specific-expander-mandrel
I am new to the "using expander mandrel instead of bushing die" so I may have screwed up the details with him
He stopped me to ask what my plan is. I told him I wanted to use it for neck tension for seating bullets. He said, Won't work. Don't order that. and told me to order this: https://21stcenturyinnovation.com/buy-online/ols/products/caliber-specific-expander-mandrel
I am new to the "using expander mandrel instead of bushing die" so I may have screwed up the details with him
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Huh. Surprised he didn’t point you to a black nitride turning arbor NBT26 (I think that’s the right part number?).
Do you mean the die that holds the mandrel? If so, yes, it will take 21C mandrels. They're 1/2" stock mandrels. (Assuming you have a relatively recent version. The really old ones came in 3/8" as well as 1/2", back when the 17 caliber mandrels were smaller. I think they're all the same now.)
Zero improvement measured how and improvement how? Are you using a honed Forster die or straight from the factory Forster FL sizing die?? If it's a straight from the factory die then a mandrel isn't going to do anything different then the button....
Do this and you'll see what I'm talking about....measure the neck diameter of a fired (unsized case) and post that measurement.... then remove the entire expander mandrel/decapping rod assembly from your Forster FL sizing die and size that same case then measure the neck again and post that measurement....now put the expander/decapping rod assembly back into your die and size another fired case just like you normally do and then measure the neck and post thst measurement....
Yes, the die that holds the expander mandrel is what I meant. Thank you for your info too
My forester die is was honed by forester. Years ago. I sent them brass from a rifle i no longer have. For my little test, I set the neck dimensions the same using a mandrel as well as just the button. Just as explained above. The outcome was the same the mandrels didn’t improve group size or Concentricity. Concentricity was measured on a Sinclair slant bed Concentricity gauge. Like anything, if your process works don’t change it. For me the mandrel was adding a unnecessary step . Your mileage may vary.
Forster FL sizing dies make great ammo with excellent runout.... The problem with Forster and other commercial FL sizing dies is they excessively work the brass. And I mean, A LOT. Following the steps and measurements I outlined above, you can see exactly how much they overwork brass.... They are made to size all types of brass with varying neck wall thicknesses, so they squeeze the neck down A LOT, then the expander ball rips that neck back open... You get what you get with that system...
I had Forster hone many FL sizing dies over the years that I sent back to them with specific measurements I wanted the dies honed to.. I would measure a loaded round and have Forster hone the die to squeeze that neck down .004" under loaded neck diameter... That way in step 2, my 21st Century Turning mandrel would only be opening the neck back up 0.002.....leaving me with exactly .002 neck tension..
The problem with this is if you load different brass for different rifles of the same caliber, you needed multiple honed dies in the same caliber for each rifle.. I have honed .223rem Forster FL dies for LC 5.56 and another for Lapua... Same for 6.5cm Lapua and 6.5cm Hornady for my gasser, etc.
I got away from all this and just use FL Bushing dies with the expander button/rod removed that way I can choose the neck bushing I want to properly size that cases neck down .004 under loaded diameter then open it up the final .002 with my mandrel, always leaving my brass with .002 neck tension and virtually no runout.
This works the brass the least and is the least hassle to get the die I want and time it takes to get it.
Big shout out to L.E. Wilson FL bushing dies! They are beautifully made, take Wilson, Redding and Whidden neck bushes, have a super smooth internal finish and size like butter. My new go to!
Correct me if I'm wrong, but isn't that why expanding mandrels are now offered in such a variety of diameters? So as not to overwork the brass? Maybe I'm missing something(?).
Expander mandrels are not what overworks the brass...The die itself, in this case a FL sizing die is what overworks the brass (squeezes it down)... The mandrel opens it back up after its already been excessively squeezed down.. Different size mandrels are so you can pick your desired final neck tension.. .001, .002, .003, etc...
Overworking of the brass happens when its excessively squeezed down way more than necessary, thats got nothing to do with a mandrel...
Here are some actual numbers I just took from a factory Forster .223rem Full Length sizing die showing what Im talking about (not honed).
LC 5.56 Fired Case Neck Diameter - 0.252"
LC 5.56 Case Neck Sized in Forster (no expander button/rod) - 0.239"
LC 5.56 Case Neck run in 21st Century Mandrel after above Forster Sizing - 0.244"
LC Loaded Case Neck Diameter with a 73 ELD - 0.246"
So, this FL sizing die is squeezing this neck done 0.013"
Then the button or mandrel is opening it back up 0.005"
My honed dies and FL Bushing dies are setup to only squeeze that neck down 0.004" under loaded and only open it back up .002 to give me .002 neck tension. So its working the brass half as much. How much this matters and how much more brass life does it give? I dont know. What I do know is my primer pockets go before anything else. Ive never seen a split neck or any issues like that....
Just some numbers to digest and better understand what Im talking about. This example is on the better side. Ive seen a lot of dies squeeze necks down even much farther.... Also, this is just with 1 manufacturer of .223/5.56 brass... If I grab a different type of .223rem or 5.56 brass, these numbers are going to change, this is where you loose control.... But if you had a FL bushing die, you can just swap bushings to keep the same amount of neck sizing between different brands of brass (varying neck thicknesses)...
LC 5.56 Fired Case Neck Diameter - 0.252"
LC 5.56 Case Neck Sized in Forster (no expander button/rod) - 0.239"
LC 5.56 Case Neck run in 21st Century Mandrel after above Forster Sizing - 0.244"
LC Loaded Case Neck Diameter with a 73 ELD - 0.246"
So, this FL sizing die is squeezing this neck done 0.013"
Then the button or mandrel is opening it back up 0.005"
My honed dies and FL Bushing dies are setup to only squeeze that neck down 0.004" under loaded and only open it back up .002 to give me .002 neck tension. So its working the brass half as much. How much this matters and how much more brass life does it give? I dont know. What I do know is my primer pockets go before anything else. Ive never seen a split neck or any issues like that....
Just some numbers to digest and better understand what Im talking about. This example is on the better side. Ive seen a lot of dies squeeze necks down even much farther.... Also, this is just with 1 manufacturer of .223/5.56 brass... If I grab a different type of .223rem or 5.56 brass, these numbers are going to change, this is where you loose control.... But if you had a FL bushing die, you can just swap bushings to keep the same amount of neck sizing between different brands of brass (varying neck thicknesses)...
Caliber Specific Expander Mandrel Kits
Our caliber specific expander mandrels are available in .0005” increments in calibers 22 to 338 and will range from .001” above bullet diameter to at least .003” below bullet diameter depending on caliber. This will allow the reloader to find proper neck tension to fine-tune their loads. The...
21stcenturyinnovation.com
You know, I used Forster exclusively for years up until a few years ago. There stuff was great. The QC started falling off, I started having issues with dies, back and forth with them telling me its fine until I had to start micing everything and putting notes in small baggies with sized pieces of brass in different stages, with expander ball, without, etc.... They would finally say the die has QC issues we are replacing it... I got tired of that and went elsewhere.
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