Lee 356-125-2R

[Jaybird721]

Just found this forum
Long time reloader, some what new to casting, and first time casting for 9mm
Trying to figure out seating depth for these guys
Like the title says Lee 356-125-2R cast 9mm
Can’t find anything in the Lyman cast handbook
Plan on pc and sizing to 357
They dopped at 357 and 128-128.5 grains
Any info would be helpful

[tazman]

They need to fit your gun barrel.
Remove the barrel from your pistol and drop a dummy round into the chamber. If it drops in completely and freely, you are good to go as far as length.
If it doesn't go into the barrel freely, you need to seat the boolit deeper until it does.

A typical place to start for that boolit is 1.159.
A lot depends on how the throat of the barrel in your particular firearm is made.

This sticky is a good place to start your reading. It contains a lot of the information you need specifically for 9mm.
http://castboolits.gunloads.com/showthread.php?121607-Setting-up-for-boolits-in-a-new-9mm

[Cosmic_Charlie]

I had to have my M&P 2.0 barrel throated in order to chamber that boolit. Lee makes a 120 gr. truncated cone mold that avoids that situation. Most 9mm barrels don't have much of a throat. I never tried deep seating the boolit because it seemed excessive ( so it might work for you ).

[kmw1954]

Jaybird721 Welcome to the forum. I do not cast or load for 9mm but do so for 45acp and 380. Make up a dummy round with no primer or powder and as tazman says seat it until it will drop in and out of the barrel freely. Then let us now what you found for a length and what powder you plan to use.

[pacomdiver]

i tried the exact same thing you want to do, the nose on that bullet is too fat when powder coated (even a light coat), i was down around 1.06 to get it to chamber in anything but my PCC's, went with the 120 TC and it works great in all my 9mms including the PCC's

[BC17A]

I've loaded the 356-125-2R as short as 1.055" and worked up loads accordingly. Never a function problem and accuracy is as good as most other bullets are at normal seating depths.

[TjB101]

I've loaded the 356-125-2R as short as 1.055" and worked up loads accordingly. Never a function problem and accuracy is as good as most other bullets are at normal seating depths.

1.05x was required for my CZ75 ... I was able to run 1.08 for my Sig’s. A lot shorter than you’d expect. Saves on powder since they are running shorter. 3.5x of BE was pretty good in two of my Sig’s last outing.

[tazman]

Sorry that I failed to notice you were going to PC the boolits. The people saying the nose will be too fat are most likely correct.
My method is still valid but you will need to start with a shorter OAL than what I mentioned unless your barrel has been throated.
I don't powder coat so I can't give you a proper dimension.

[Conditor22]

Welcome to CB Jaybird721

there is no best OAL for cast boolits, you have to find the best OAL for each of your guns.

With cast boolits, you find a boolit with the same weight and start your load development from there. there many variables that come into play for any given boolit.
Profile of the nose, the thickness of the PC (powder Coating), how hard the alloy is, how big you're casting them.

PM sent with more information

[Cosmic_Charlie]

With my Apex barrel seating them to 1.062 works fine. 3 gr. of Titegroup gets me about 1000 fps. with full function. Loaded some more up with 3.3 to get a bit more velocity but have not shot them yet.