What would you do next?

[wv109323]

I have been trying to cast and load for a 9MM CZ 75B Omega without any success. I need your suggestions for a corrective plan.
The bore slugs at .3558 to .3560.
There is next to zero freebore or lede in the chamber. So all cast boolits of .356 or larger need to be seated so there is no major diameter of the bullet extending out of the case.
I use range lead from a Bullseye pistol range for my casting. My bullets are hard enough that you can not begin to scratch them with the finger nail. I don't know the actual hardness.
My problems are terrible leading and bullets keyholing.
I first tried a RCBS 124 TC boolit. It cast at .356 and keyholed. I thought bullet to small.
I next tried a Lee .358 125 RNFP mold and seated to the crimp groove(with a taper crimp of .380). These were sized at .3577( that is what my Star .358 die ends up being). These bullets would not function. At this length the chamber would shave lead off the boolit and accumulate at the front of the chamber. Within 15 to 20 rounds you would have enough lead build up that a round could not chamber.
When the OAL was reduced to the point where the beginning of the ogive was at the case mouth normal powder loads were compressed. I did not pull one of these boolits to see what the diameter was after seating.
I next got a Lee .356 120 TC mold. These cast at .358 and were sized to .3577 with White lube. The neck sizing of the Dillon powder funnel is .3535. A pulled bullet is .3570. With 3.6 gn. of BE I get terrible leading and bullets keyholing. About 1 in 5 keyhole completely sideways through the target at 7 yards. These boolits are seated with the shoulder of the bullet flush with the end of the case.
Jacketed bullets shoot fine.
Would you ream the chamber?
Would you get a larger neck expander?
Would you get a harder alloy?
A different mold?

[DrCaveman]

Maybe try a Lee .356" sizer. Seems like it would work well with your stated measurements. Maybe hone it out later to a little larger, but it would be worth trying. And bump up the charge while you are at it.

[Piedmont]

I don't know what White lube is. You stated you used range scrap but not whether you air cooled or water dropped. Here is what worked for me: hard bullets (water drop them), no tumble lubing (use real lube in the grooves) and sizing to .358". If you use hard bullets you don't need to worry about expander sizes.

Is your Lee 120 TC a tumble lube design or does it have regular lube grooves? If it has standard grooves I would begin by water dropping it and putting lube in the grooves. Use the sizing die you have. There will be springback with the harder bullet so they will be a little larger, even sized in that same die. See what happens.

[wv109323]

White Label( LS Stuff) is a vendor here. The lube these bullets had is their X-Lox 2500. The Lee 120 TC has a single grease groove, not a tumble lube design. Bullets were lubed in a Star Lubri-sizer. Bullets were air cooled. I will try more velocity to stabilize the bullet.

[rintinglen]

Stop the music! I'd ream that chamber leade in a heart beat. From your description, there is not currently any throat. It goes "chamber," "rifling," with nothing in between.

[tazman]

I agree with rintinglen about the chamber. If there was ever a good candidate for chamber throat work, you just described it. Your only other real option is to give up on cast altogether and that is against what we do here.

[wv109323]

Rintinglen,
your description is fairly accurate. To look the rifling, at the end of the chamber the raised rifle has a diagonal cut. One edge of the raised rifle extends to the end of the chamber. All six rifling is this way. I don't know how they made it end up this way. Any rotary cutter would cut the end of the rifle parrllel to the end of the chamber. As best I can tell there is .006 to.008" between the end of the chamber and the beginning of the rifle. On a CZ forum this is common and normal.

[scattershot]

You eon't say what your load is, but try dropping it a little and see if that helps.

[Groo]

Groo here
Don't CZ's use a polygon rifling?
You may need plated,gascheck, or water dropped boolits.
Also try the "coated" boolits, SNS , Falcoat,etc.

[wv109323]

Load is 3.6 gns. Of BE.
CZ has rifled barrels. It is Glock withe polygonal.
I may try water dropping.

[runfiverun]

I have a cz-75b retro.
I use the same thing I use in my tokarovs and HI-point carbine.

the mold is the HM-2 9mm mold I designed I seat the front shoulder to the case mouth same as I do with my 45 acp loads when using a shouldered boolit.
I size to 358 and use ww and linotype mixed 8 to 1 for my air cooled boolits, and place them on top of 3.2 grains of red-dot.
I think I could make things a tick better but off hand 25yd groups of about 2-1/2"s is pretty good for me.
I do pick up a little trash in the chamber about every 50-60 rounds but it pulls out with the round that doesn't want to chamber.
a good bit of that trash is caused by the super wet lube I'm using right now.

in this case I would look at your boolit design and then search around a bit for something like the rcbs truncated cone boolit, and work on the alloy a little bit.