Lee 'U' (Undersized) dies

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Lee 'U' (Undersized) dies

Postby Hawkmoon » Tue Sep 23, 2014 8:02 pm

Lee 'U' (Undersized) dies: http://www.midwayusa.com/product/572212 ... viewHeader

Has anyone tried these? Do they work as advertised? I don't have major problems with setback, but I do remove the magazine when storing or transporting a pistol, and then I reload and re-chamber a round. I try to mix it up, but it's possible for one round to be chambered two or three or four times before being shot. Multiple chamberings in a 1911 can induce setback, so I'd like to minimize the possibility.

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Postby erle » Wed Sep 24, 2014 12:16 pm

The "U" die won't affect setback. It only resize the brass, mainly the base, just a little smaller to assure feeding if fired in multiple pistols. I use them on .223 & 9mm.

To avoid setback, get a Lee Factory Crimp Die & install it in the last stage. Be sure to adjust the crimp so all the case neck does not crimp into the bullet. You must have some case neck exposed for the cartridge to headspace on. I leave about 1/2 of the neck exposed.

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Postby Hawkmoon » Mon Sep 29, 2014 10:23 am

erle wrote:The "U" die won't affect setback.

That's not what experienced reloaders on other forums say.

I use the Lee FCD as my fourth station. I know shooters with many years more reloading experience than I who WON'T use it, on the basis that anything done to the base after seating the bullet reduces the grip on the bullet. That said -- both the resizing die and the FCD adjust the external (outside) diameter of the case. But not all case walls are the same thickness, so a die that works well with thick-wall cases may not provide a tight grip with thin-wall cases. That's what the U dies are supposed to address.

I'd just like to get some feedback from people who have actually used it.

Sample tabulation of case wall thickness, in .45 ACP (courtsy of M1911.ORG):

https://docs.google.com/spreadsheet/ccc ... _web#gid=0

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Postby THRASH » Thu Feb 11, 2016 12:38 am

On my LLM I have used the U die for both .40 & .380, set in station #2 w/o decap pin, but start with the standard .40 or .380 Sizing die w/o decap pin at #1. I deprime all dirty brass first with a universal deprimer ONLY turret, then rotary tumble with SS pins & clean pockets, etc. then run all cases through my Bulge Buster before running the main loading turret. I put a very light crimp w/FCD at #5.

Prior to using the U die cases were sometimes slow to extract/eject and would get slide-crunched a touch (likely Glock cases I p/u?), something I posted about here a while back
http://forums.loadmastervideos.com/foru ... ght=#22723
Since using the U dies there have not been any ejection probs whatsoever.

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Postby darwin » Fri Feb 12, 2016 9:13 am

How often do you do this?

I don't do it very often. but occasionally rotate the top round to the bottom.

My suggestion would be to measure the top round with a digital caliper to see exactly how much and how quickly or slowly they set back.

Another idea would be to run around the rim of the cases with an extra fine Sharpie so you could visually verify if the bullet has moved.

I carry my carry gun in a holster all of the t ime or have it right next to me at all times, so I seldom have to remove the magazine or clear the chamber

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Postby WyrTwister » Fri Mar 18, 2016 9:01 am

Are " U " dies kind of like small base dies , in other brands ?

God bless
Last edited by WyrTwister on Tue Mar 29, 2016 3:18 am, edited 1 time in total.

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Postby carload9 » Mon Mar 28, 2016 10:07 pm

Get a cartridge gage too for true perfection.

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Postby Chickenthief » Tue Mar 29, 2016 8:29 am

WyrTwister wrote:Are " U " dies kind of like small base dies , in other brands ?

God bless


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