This is what happens when I try to tumble lube...

[tyeo098]

Lee 120gr TC: Harder than fingernail scratch, lube-size-lube with straight snot LLA sized .357
3.5gr Bullseye
1.05" OAL.

I'm thinkin my boolets are too hard, or my load is too hot for the OAL.
I have some 45-45-10 at the ready, but have no 'in the white' boolets to coat it with.

Gun was my baby- a (now very clean) 2009 CZ75B

[nhrifle]

Leading like that usually points to an undersize boolit. If you haven't yet, slug your bore, measure the high points, and size a thou or two over that to provide good gas seal.

[geargnasher]

Impressive!

Now pull a boolit from one of your loaded rounds and measure the diameter of the driving bands. I'm betting they're considerably smaller than .357".

Gear

[geargnasher]

Leading like that usually points to an undersize boolit. If you haven't yet, slug your bore, measure the high points, and size a thou or two over that to provide good gas seal.

Beat me to it. Looks like a classic example of case swage. Forget the groove dimension, size to the throat entrance diameter if it has one and us a .38 Special expander spud.

Gear

[tyeo098]

Huh.

I did all of that.

CZ75 Barrel slugs out to .356"

I have a leftover round that FTF'd (or I ejected it for some reason... iunno) I'll pull it and verify.
(Actually that will have to wait since my gf just showed up and wants to watch movies lol)

[capt.hollis]

Lee 120gr TC: Harder than fingernail scratch, lube-size-lube with straight snot LLA sized .357
3.5gr Bullseye
1.05" OAL.

I'm thinkin my boolets are too hard, or my load is too hot for the OAL.
I have some 45-45-10 at the ready, but have no 'in the white' boolets to coat it with.

Gun was my baby- a (now very clean) 2009 CZ75B

I doubt that bullet is too hard . Definitely got something else going on there. Only time I seen that when I sized my 30 cal blackout to .309 when I should had left the bullet alone.

[fryboy]

you can coat any of the umm not "in the white' projectile with any kind of tumble lube , rooster jacket for example used to state to do it to jacketed to help reduce fouling( i'm going to assume carbon and copper on that one as i never tried it ) and folks have been known to coat store bought boolits to cover up the hard lube
i also admit that i didnt check your load data or pressure level [shrugz]

[tyeo098]

Pulled bullet measures out at .357".... So it doesn't seem to be swaged.

The leading only seemed to be happening in the last 1.5" of the barrel or so. Is it lube failure?

[Wally]

I shoot the Lee 120 TC 90239 and use the same Powder Charge in my Taurus 99AF... Accurate with minor leading--I size to .358" and use regular lube...is the bullet you are using the TL 90238 style? Others have mentioned that the TL bullets don't do well in a 9mm Luger..

[tyeo098]

Wally- what OAL are you using?

[ZigZagMarquis]

Yikes!!

I thought I had leading problems!

Now I realize I don't.

You Win!!

[Wally]

Wally- what OAL are you using?

1.057"

[tyeo098]

I'll trade ya my TL mould for your regular one

I'll have to load up some with that 45-45-10 and see if it makes a difference.

[Full Mold Jack]

You could try lube-size-lube-lube

I have one gun that prefers a good coating of that snot.

[fixerupper]

Check your crown.

[zwv1951]

If bullet is sized right then go with a slower powder.... Unique or slower. This along with 45/45/10 solved leading problems in my 9mm and .40sw.... Bullseye works ok in my .45 but it has a much lower cup pressure...

[tomme boy]

I had problems also when I used to use the ALOX. What I found was to give two coats after sizing. That helped mine.

[wistlepig1]

I have seen leading in wheel guns but nothing like that, no suggestions here. WOW!

[Love Life]

Tumble lube the already lubed bullets with a coat of 45-45-10. Looks a bit like a case of lube not making the whole trip down the barrel from the pictures. Now if the leading goes down the entire length of the barrel, then I got nothing except for you to try a new lube. Might I suggest Lotak Hard or Speed Green?

[220]

I had similar issues in 9mm using the lee 124conTL cast from WW, accuracy was acceptable from a clean barrel but leading would be that bad after 50 shots that bullets would start tumbling.
Only solution I found was to drop velocity to about 900fps, pressure with the load is also much reduced and while leading hasn't been entirely eliminated, even 300rds still sees acceptable accuracy no tumbling and only minimal leading.