BIG hardness change, I'm stumped

[knotbrush]

I was having problems with my 9mm 124gr TC TL Lee molded bullets keyholeing and leading the first two inches of the barrel. The load was 3.5gr 700-x. The advice was:
1. The bullet's too small. -They measure .356" The BBl is .355
2. The lead's too soft. -They measured 14 BHN

So, I added a 2lb. ingot of linotype to 18 lbs of wheel weigh ingots and water dropped. Those bullets measured 18.4 BHN. Now a month later, I finally get back to the 9mm. (I'd been avoiding the frustration) I accidentally dropped a couple onto the heavy aluminum plate on my bench and they sounded like steel ball bearings. I know they get harder with age so I retested the hardness. 27.4!!! ***! Now I wonder.......the .38 SWCs I made with the same batch of lead had HORRIBLE accuracy. I went from 1-1/2" groups at 30' to 6" groups.

So, what do I do with all these (600) .38 boolits I made that are 27.4 BHN? It seems like the more I learn , the less I know, and more and more variables are getting out of control. Should I even try the 9mm boolits? What happens if they DO work, will I be able to reproduce them?

[lwknight]

Remelt them.
Add more linotype
And do not water drop them

The 10% lino added only raised your antimony by 1.2 percent.
Your alloy is probably about 4.5% antimony and 1/2% tin unless you added extra.
There is a reason that the 2-6-92 Sb-Sn-Pb is popular. Its about 15 bhn without quenching.

[Bwana]

I don't know; but, I run very hard water dropped ww boolits sized to .358 in my 9mms and 357Sig using a medium hard lube. No leading in my bbls, including my factory G-19 and G-32 bbls.

[w30wcf]

If they are not lubed, I would put them in a toaster oven at 450F for 1/2 hr or so. Then turn the oven off and after everything coold down remove the bullets. THe bhn will then be as cast or close to it.

If the bullets are lubed you could put them in an old pot and boil them to remove the lube first.

w30wcf

[Gohon]

Just oven heat treat them at 360-400 degrees for an hour, turn off the oven and let them air cool with the oven. They'll return to what ever BHN they would have been if you hadn't water dropped them. Was the 18.4 BHN taken immediately after casting or did you wait a few days? You want to wait at least a week after casting to test BHN.

[Bass Ackward]

Another way to soften them is to boil them.

That gives me more control than the oven technique. I can pull one out every so often and test until I get the hardness I want, then drain the batch.

[fredj338]

Try a diff powder. The 9mm seems to be one fo the most finicky when it comes to getting good accuracy. I have a BHP w/ match Barsto bbl. I could not get 14BHN RNL bullets to group well using W231. I changed to Unique & it was like shooting jacketed. Other powders worked as well, but that gun would not shoot over W231 w/ 124grLRN or LTC.