Lee molds--9mm RN 125gr vs TL124gr.


Deus Machina
February 14, 2010, 06:17 AM
I've got the non-tumble-lube 125gr 2R RN mold, and have problems with the bullet wedging itself into the lands on my CZ, unless I seat it well under what my manuals state as the min OAL. It works, mostly and carefully, but still jams up when I get one that slips a little, and I'm not particularly happy with having to load a round to 1.05 or under, when everything says it shouldn't drop below 1.16.

I can see the step in diameter on the 124gr TL mold, and have heard a few reports that it cuts out the jamming that CZ's are prone to in that regard.

And, with the tumble-lube grooves without that expanse bare lead in front of them, I think it may allow me to load a little warmer without increasing the mild-but-noticeable leading I get even at quoted middling loads for the lead.

After all, what's the point of reloading without improving things? :p

Anyway, can anyone else back this up first-hand? Or, even better, have one of the dimensional drawings that I could compare? I've seen them for the Lee dies, but can't find them again. Sigh...

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February 14, 2010, 09:41 AM
I am also having issues ,but with 40cal,175grn tc. hitting inside camber of my XD.General opinion is to seat far enough to camber then adjust powder charge down and check for pressure signs.I'll know today after I run them through the crono.

February 14, 2010, 11:31 AM
I use Lee TL356-124-TC bullets, and seat the bullet deep enough that all TL grooves are covered by the shell to have rounds chambered properly. This gives OAL 1.063...1.065", which is way less than max OAL for the caliber (1.169").

Powder charge does need to to be reduced from the bullet of the same weight and the design that should be seated to the full OAL. For powders, which I use, the charge reduction to keep the same pressure with the reduced OAL, according to QuickLoad, is about next Lee disk in the powder measure, or about 7 percents.

Deus Machina
February 14, 2010, 01:20 PM
I've got the powder charge reduced. Like you said, Helg, the next step down.

Mostly, I want to get the OAL closer to where it's supposed to be, and hope that a TL-style leads less than the barely-lubed single-groove.

February 14, 2010, 02:06 PM
I have a conventional grease-groove Lee mold for a .45 ACP 230 grain TC bullet.

Same problem with it jamming into the leades on two 1911's unless seated shorter then I prefer to make them feed.

Lee just don't get it yet on designing bullets, I think.


February 14, 2010, 02:46 PM
In my mind, cast bullets are more sensitive than jacketed to the length of "bearing surface" - the length where diameter of the bullet is equal to its caliber. Bullets with longer bearing surface should align better in the bore thus providing better accuracy. Also, longer bearing surface provides more torque to spin bullet by the rifling, and withstands higher pressures before breaking the bullet off rifling and start leading.

I have two Lee molds, both of the same bullet weight, and both TL design: TL356-124-TC and TL356-124-2R. With the second I can not get accuracy of the first. I doubt that shorter bearing surface of the RN design of the second mold contributes the main role to the accuracy.

With this in mind, cast bullet design of SWC/TC type that has to be seated deeper look preferable for cast bullets of the same weight than the bullets with short bearing surface that can be loaded to full OAL for the caliber.

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