RCBS 6.5-140-SILH in .260 Rem

[blue32]

I've been working up a load with this bullet using Unique (using 7mm-08 as a baseline for data, Lyman Cast 4th ed.) and the groups are shrinking at 1,649 fps. But I've gone as far as I can with range scrap as lead is building up around the muzzle. I'm going to have to buy some alloy to mix with the RS and I'm wondering what would be the most direct way of arriving at 15-16 bhn to mix without going straight store bought alloy. The RS is hovering around 10-11 bhn.

I've been looking at rotometals and am curious about mixing in their 30/70 lino. Would that be overkill; should I start with Lyman 2 or something else?

[reed1911]

I would get some high antimony lead like this http://castboolits.gunloads.com/showthread.php?293387-F-S-Lead-92-5-Antimony-(SB)-7-5-Ingot-bars-(Start-shipping-12-10)
(http://castboolits.gunloads.com/showthread.php?293387-F-S-Lead-92-5-Antimony-(SB)-7-5-Ingot-bars-(Start-shipping-12-10))
That will allow you to harden up the alloy directly as well as offer heat treat and age harden options. And it is cheap! I have no dog in the race with that seller, but I have bought from him before it his lead is great!

[gundownunder]

clip on wheel weights should have a BH of about 12 and can be heat treated. WW with 2% tin added should get you well above where you are at now. I know that WW + 2% will get me 1750 fps out of a 357 with 180 gn bullets and I can shoot 100s without any leading.

The enemies with cast bullets are, pressure, and bullet diameter. Contrary to popular belief, velocity is not your enemy. If the bore on your rifle is .264, you want a bullet of .265 - 266.
If you can find a powder that gives you more velocity with less pressure, change to that powder.

[Yodogsandman]

The cheapest and easiest way to increase your BHN hardness is to water drop the boolits right from your mold into a bucket of water. Any alloy that contains some antimony can be heat treated to a harder BHN. Your range scrap will increase in BHN by about half again this way so, to about 15-18 BHN. BHN will vary a little with this method depending on the consistency of dropping the boolits in the water the same each time..

If you want them harder, oven heat treat them with a convection toaster oven and quench in cold, cold water. The bigger the temperature difference between the hot boolits and the cold water, the harder the boolits will be. Find the "slump" temperature of your alloy by testing a boolit in the oven at higher and higher temperatures until it slumps. Then back off on your oven temperature by about 10*F or 20*F degrees for heat treating. This slump temperature will probably be from about 480*F to 500*F. Place boolits evenly in a tray and heat soak in your oven at that lower temperature for at least an hour before quenching them in ice cold water for the hardest boolits from that alloy. This method will almost double the BHN hardness of your boolits so, maybe up to 20-22 BHN. BHN consistency is better this way too. Trying different oven temperatures allows you to customize the BHN that you want.

Heat treated boolits can be loaded and shot sooner than regular, age hardened boolits. For regular age hardened boolits, I wait for 3 weeks before loading. With heat treated boolits, I only have to wait 5 days.

Be aware that long, thin boolits can be bent during sizing. A harder boolit and a push through sizing die, like the Lee, will help with that.

[runfiverun]

if your willing to settle more in the 17-18 bhn area you could forego the buying stuff part and just drop your boolits from the mold into cold water.

[blue32]

Thanks for the replies. It'll take me a while to try all of those out.

[dubber123]

I would also consider lube as a factor. It's a different critter entirely, but I am shooting completely leading free at 2,150 fps. in my .35 Remington using a 9 BHN alloy. The fast twist of many 6.5s may be what you are fighting, and a harder/tougher alloy will help if that is the case.