21st Century Shooting New Expander Mandrels .0005" Increments!

[Petros284]

Coming very soon to our website! Our expander mandrels in .0005" increments over and under bullet diameter. These will initially be available in Stainless Steel and in each popular caliber (.22-.338). We will be making them for large caliber in the future as well (375, 408, 416, 50). TiN coating will also be looked into eventually also. I will let you know when they are available for ordering!

 

[Boatschool02]

Good news.
Thanks.

 

[SG4247]

Finally! Thanks!

 

[Howland]

Need;
0.3355"
0.3350"
0.3345"
0.3340"

Can you overnight so I can work up some test loads and hit the range Sunday?

Kidding (only a little), but definitely counting on you to post when available for ordering.

I've come to the conclusion that 0.002" is just not enough for the .338LM.

 

[Petros284]

Need;
0.3355"
0.3350"
0.3345"
0.3340"

Can you overnight so I can work up some test loads and hit the range Sunday?

Kidding (only a little), but definitely counting on you to post when available for ordering.

I've come to the conclusion that 0.002" is just not enough for the .338LM.

Will do! Thought that with the bigger calibers there would be a larger range of sizes. Thanks for the feedback!

 

[Howland]

Will do! Thought that with the bigger calibers there would be a larger range of sizes. Thanks for the feedback!

I ran OCW throughout the range in Hornady X. A very modest charge gave the best accuracy with new Lapua brass.

Using once fired brass with carbon inside the neck, the same load still gave the best accuracy despite velocity ES over 200fps - until I got to the ones seated the deepest. Yeah, I did seating depth testing at low, mid and high range. Hey, accuracy said low range, almost indistinguishable point of impact change said mid range and low ES and velocity change said high range.

My theory is that there just isn't enough tension to contain the pressure enough for reliable and complete ignition (but only at very modest charge weights) until I reduce case volume enough to reach a "tipping point."

Tighter bushings have been ordered but I still like the idea of controlling grip by controlling inside neck diameter. I don't plan on getting into turning necks. When ordering the new bushings, I also looked for a custom mandrel but apparently they're all made out of unobtainium.

Nice job finding a gaping hole in the market.

One question. If those are expander mandrels, how will they pass through the neck without being a button? When attached to the decapping rod it keeps the expander centered.

 

[Petros284]

One question. If those are expander mandrels, how will they pass through the neck without being a button? When attached to the decapping rod it keeps the expander centered.

When used in the 21st Century Expander Body they float and self center during sizing.

 

[dolek]

Great news, I will be following this thread...Thanks for posting.

 

[spife7980]

One question. If those are expander mandrels, how will they pass through the neck without being a button? When attached to the decapping rod it keeps the expander centered.

When used in the 21st Century Expander Body they float and self center during sizing.

To expand on that answer, they dont go in the sizing die. They go in a separate expanding die. The mandrels add an additional step.
http://www.xxicsi.com/expander-die-body.html

 

[Ledd Slinger]

Nice. Same price as normal expander mandrels?

Will they be available for purchase in sets?
Would use them for adjusting neck tension so wouldnt want any 'over' bullet diameter. Would like to see sets in a similar fashion as the Whidden expander ball sets.

Thanks.

 

[mikecr]

Do they fit in Sinclair's expander dies?

 

[Bob L.]

Do they fit in Sinclair's expander dies?
View attachment 1098084

I tried an existing 21ST Century expander mandrel in my Sinclair an hour or so ago. It fit nicely.

 

[Petros284]

Do they fit in Sinclair's expander dies?
View attachment 1098084

Yes same size shank. 3/8 inch

 

[Petros284]

Nice. Same price as normal expander mandrels?

Will they be available for purchase in sets?
Would use them for adjusting neck tension so wouldnt want any 'over' bullet diameter. Would like to see sets in a similar fashion as the Whidden expander ball sets.

Thanks.

Still working out pricing. There is an additional step involved. I believe we will give a price break for “sets”. I’ll let you know as soon as I know.

 

[BenPerfected]

K&M also has expander mandrels in .0005 increments. Excellent customer service.
Ben

 

[Petros284]

These will not be “custom” order

 

[flintcreek6412]

Will the sizes on them be exactly what they are? Reason I ask is I've bought some elsewhere that were supposed to give .002 and .0015 neck tension so I assumed they would measure .3060 and .3065. They don't. They actually measure .3070 and .3075 which would give me .001 and .0005 tension and that's exactly what I get. When I called and asked they said I measured wrong but they do account for some springback. I didn't measure wrong which was obvious when I seated bullets and had minimal neck tension but I wasn't going to argue the point. I anneal every firing and don't get any neck spring back so they are useless to me now.

I want to order something knowing exactly what it measures and it will be up to me to know what kind of spring back I do or don't get and what my actual bullet diameter is. Funny how my 185 Hybrids measure .3075 and 200-20x measure .3080. That .0005 makes a huge difference.

If it says .3060 on it and that's what is measures I will be very happy and order a set right away.

 

[Petros284]

Will the sizes on them be exactly what they are? Reason I ask is I've bought some elsewhere that were supposed to give .002 and .0015 neck tension so I assumed they would measure .3060 and .3065. They don't. They actually measure .3070 and .3075 which would give me .001 and .0005 tension and that's exactly what I get. When I called and asked they said I measured wrong but they do account for some springback. I didn't measure wrong which was obvious when I seated bullets and had minimal neck tension but I wasn't going to argue the point. I anneal every firing and don't get any neck spring back so they are useless to me now.

I want to order something knowing exactly what it measures and it will be up to me to know what kind of spring back I do or don't get and what my actual bullet diameter is. Funny how my 185 Hybrids measure .3075 and 200-20x measure .3080. That .0005 makes a huge difference.

If it says .3060 on it and that's what is measures I will be very happy and order a set right away.

Yes these will be exactly what they are supposed to be. We will be taking steps to check this while they are being produced and quality checked. These will all be checked by high grade calibrated micrometers prior to packaging.

One of the reasons we are not going with the TiN coating initially is that our coating is done at an outside source and we cannot guarantee how thick it goes on. We will be looking into this as an option only if we can get consistency.

Thanks!

 

[TackDriv3r]

Would those mandrels work in a Sinclair Gen. II expander die? I'm interested in the .0025 and .003 mandrels. Hopefully they come in carbide as well.

 

[Puzzaz01]

Please keep us posted. I'll be ordering as soon as you have them ready to ship.

Darrin