Cast bullets, alloy, BHN, and MV

[Naphtali]

For my gas checked 45-70 bullets, really for all but muzzleloaders, I cast with either wheel weight or W-W+2. The results are relatively hard bullets that withstand any velocity I choose.

I'm curious about how soft these 405-, 420-, and 425-grain LFN GC bullets can be cast while retaining their ability to be propelled at 1750-2000 fps (depending upon which weight I choose).

Does alloy make a difference in how leading-free a soft bullet will shoot? For example, bullets made of 10:1 lead:tin drop at about BHN 14. I know of no one, even friends who shoot BPCR matches or who muzzle load for ridiculously large game, who cast projectiles with such high proportion of tin.

[Larry Gibson]

I shoot soft alloys (mostly WW/lead at 50/50 and AC'd) at higher velocity (1800 - 2200 fps) for hunting but have found accuracy begins to go after 5 - 7 rounds. That is ok for hunting though. For practice I just cast the same bullets out of WWs + 2% tin and then can shoot them pretty much all day long without any leading.

I use a 1-16 alloy for replicant M1881 45-70 BP and smokless loads because that is the alloy the arsenals found works best. At 1250 fps the expansion of the 460500 bullet is still very good.

I also use that same 1-16 alloy for my .50 cal 350 gr TC MiniBalls. I push those to 1570 fps out of my TC Black Mtn Magnum with FFFg 777. I use a lubed felt wad under the bullet.

I also use that same alloy or the WW/lead 50/50 alloy AC'd in Lees C457-500-F in my 450-400-70 (Siamese Mauser 45-70) pushed to 2000 fps. The expansion and penetration in elk is hard to believe!

In my other CF rifles of .30, .31, 8mm, .35 and 375 I use the AC'd WW/lead alloys for hunting and push the velocity to 2000 - 2200 fps with medium or slower burning powders.

Larry Gibson

[mooman76]

5% tin is suppose to be the maximum benificial for tin in a lead bullet. After that you are just wasting tin. If you want to go harder you need to and something else also like antimony.

[runfiverun]

at 10-1 [10%]you are in the land of diminishing returns and are just lowering the melt point of your alloy.
at 20-1 [5%] your tin lead alloy is as hard as ww's are.
thats where i'd start and go down till you see results good or bad.
3% tin 32.3-1 should be a viable alloy.
remington and winchester used 40-1 and even 50-1 in thier revolver/levergun cartridges forever.

[geargnasher]

at 10-1 [10%]you are in the land of diminishing returns and are just lowering the melt point of your alloy.
at 20-1 [5%] your tin lead alloy is as hard as ww's are.
thats where i'd start and go down till you see results good or bad.
3% tin 32.3-1 should be a viable alloy.
remington and winchester used 40-1 and even 50-1 in thier revolver/levergun cartridges forever.

+1.

Gear

[MtGun44]

GC seems to correct most issues with softer alloys. I normally shoot AC WWt in
my .45-70 with the RCBS 405 GC at 1750 using a fairly slow powder (W748) and get
very good results. IMR4064 and H332 (IIRC, check that, please) are similar burning speed.

I haven't tried much softer in the rifles yet.
Bill

[Marlin Junky]

Does alloy make a difference in how leading-free a soft bullet will shoot?

Yes and so does chamber pressure, boolit diameter, rate of twist, land height/groove depth, number of grooves, barrel smoothness, velocity and lube. In other words, anything that can cause a gas leak or excessive friction. Therefore, to address your curiosity, you'll simply need to try that BHN 10, gas checked boolit at x fps in order to find out. Have fun isolating all the variables... you should have a few 45-70's available for testing that have somewhat different barrel configurations before drawing any conclusions.

For example, bullets made of 10:1 lead:tin drop at about BHN 14. I know of no one, even friends who shoot BPCR matches or who muzzle load for ridiculously large game, who cast projectiles with such high proportion of tin.

Sn was the Pb hardening agent during the BP era and I don't recall hearing of alloys richer in Sn than about 16:1. Using 9% Sn (10:1) today would be considered wasting money and a pinch of Sb coupled by a heat treat or water drop straight out of the mold will get one a heck of a lot more hardness for the buck.