Heat treating gone bad

[Gunslinger]

I have a leading problem with a CZ SP-01. Straight WWs at 1020fps leaded badly. I made a new alloy which is 4-1 WW-lino, that solved the problem, but I'm out of lino, so I wanted to try heat treating the same boolits made from straight WWs.

I followed Veral Smith's instructions from his book. It said to find the booolit's slump temperature. I honestly don't know what "slump", means but I figured you should increase the temperature until the boolits started to "sweat" metal. I couldn't get them to do that so I gave a batch of boolits one hour at 480 degrees. Upon adding the boolits to the water, they slid down the pan and ended up looking like this. I assume the temp was too high.

At which temperature should I heat treat boolits made from WWs? (120gr TC 9mm)

[Von Gruff]

This page may be helpful.



Von Gruff.

[Ole]

I have always used 440-450 degrees as a target temperature when heat treating wheel weight bullets with an oven.

[snuffy]

Looks like you found the slump temp! Those boolits are partially melted, that's what "slump" means, about to melt. How hard are they? The ones that aren't deformed may be useable if hard enough.

It almost sounds like you don't have a hardness problem, but one of fit to the barrel. The harder alloy you made up probably cast a bigger boolit, even though you sized it, it may have sprung back with age. Have you slugged the barrel?

[btroj]

Think of this as a learning lesson. Sometimes we need to know what doesn't work to help find what does.

[Pat I.]

Get a good accurate oven thermometer set the temp to 440 to 450 like was said above get the bullets in the water as fast as possible and they'll be harder than Chinese algebra, or over 30 BNH.

[docone31]

It looks like you have enought tin in the alloy, you might consider adding lead.
You want the temp up some.

[Shuz]

Get a good accurate oven thermometer set the temp to 440 to 450 like was said above get the bullets in the water as fast as possible and they'll be harder than Chinese algebra, or over 30 BNH.

I believe an oven thermometer is the only way you can be sure of the temp you are seeking. I use an old toaster oven and once the "control" was set that gave me the desired result, I simply unplug the toaster oven when I'm done. This pretty much guarantees that I'll be at the right temp next time. So far it has worked very well

[RobS]

A good thermometer is a good investment if a person whats to know what's going on in the oven. Your 4 parts WW to one part lino is a lot softer (around 14 BHN) than a water quenced WW at nearly slump temps (upper 20's to 30's BHN).

A good read for you:
http://www.lasc.us/HeatTreat.htm

General info, also a bit about alloy mixes (at bottom of page):
http://www.lasc.us/CastBulletNotes.htm

[sqlbullet]

For that hardness, just heat them to 350° and dump them. You should easily get a BHN of 20 that way.

Also, if you have good cadence and temp control on your lead and mold, just water drop from the mold. All you are really trying to do is quench a hot bullet from a consistent temperature. The bullets are hot when they leave the mold, and with good cadence, the temp is consistent. I have not seen a difference of meaning in either hardness or standard deviation between oven quenched and quenched from the mold.

[Frozone]

I'll second that water drop.
At least try it first before you get into oven heat treating, it's a bit of a pain to oven treat 1000s of boolits.

[1Shirt]

Suggest cast very hon and just water drop them and forget heat treating. You will probably find it to be satisfactory, and a lot less work. Just my opinion.
1Shirt!

[Gunslinger]

Thanks for the replies!!

The barrel slugs at .3559 measured with a micrometer, and the bullets are sized .357. My own gun shoots the exact same bollit without leading. But in the CZ, at 12 yards groups are the size of a dinner plate, half the boolits tumble in flight... and the barrel was LEADED - thank God for Chore boy.

I'll try water quenching them instead. I don't need the kind of hardness obtained by heat treating anyway. I haven't done much water quenching since I used to use 3 molds at the same time, so my temp was never very consistent. I now use one 6cav mold only, and melt lead on a hot plate and add molten lead to the pot. So I guess I'm now able to keep a more consistent temperature.

[JIMinPHX]

Heat treating a whole batch at a time gives you the best consistency, but just water dropping the boolits as they leave the mold usually gives me about 90% of the hardness that I would get from a heat treat. I just water drop unless I want to do something really special for long range use.

[nanuk]

I gotta wonder tho, your boolits are sized 0.0011 over groove diameter, and WW "Leads" at 1020 FPS?

but HARD boolits don't?

is this normal for that type of pistol?

[Frozone]

I gotta wonder tho, your boolits are sized 0.0011 over groove diameter, and WW "Leads" at 1020 FPS?

but HARD boolits don't?

is this normal for that type of pistol?

3 ways to get leading:

1, running out of lube
2, blowby (undersized, no obduration)
3, skidding in the grooves.

#1 shows up at the muzzle end.
#2 shows at the throat, with rather even deposits
#3 at the throat but lead is deposited unevenly on one side,the "downwind" side, of the grooves.

In 9mm I've experienced ALL the problems

#1 is rather easy to fix.
#3 requires a hard boolit.
#2 is a balance of Hardness and charge weight. The harder the boolit the narrower the charge range that won't lead.