Copper alloy rifle boolit results

[oldandslow]

Greetings casters, 8/1/13

My problem was with the nose of my 30-06 boolit, AccurateMolds #310-180-F (gas checked), twisting off at velocities of 2200 ft/second. The same boolit would hold together and retain 96% of its weight at 1845 ft/second when recovered from water soaked paperback books (Jane Fonda' My Life My Way, SAT Study Guide, Federal Tax Code, etc.) bought for $0.50 each at my local Salvation Army store.

Many helpful posters have recommended various options such as keeping the velocity down, adding more Tin (Sn), Antimony (Sb), arsenic or Copper (Cu). Below are the results with increasing tin, antimony and copper percentages in my base alloy.

Rifle and load data- Howa 1500 30-06, 1:10 twist, with 200 rounds of jacketed bullets before lead testing. Powder-40 grains 4064, Winchester LRP, Winchester Brass, boolits are 0.010" off lands.

Alloy type

Base alloy- 97.1% Pb, 2.22% Sb, 0.435% Sn ------ retained wt.38%----Ice water dropped----BHN 20.9

Base alloy plus 2% Sn-----------------------------------40%---------------70 deg. WD-----------14.3
Base alloy plus 2% Sn ----------------------------------63%----------------IWD------------------16.6

Alloy #1- 94.9% Pb, 2.7% Sn, 2.3% Sb, 0.11% Cu---73%----------------70 deg. WD-----------15.4
Alloy #1-------------------------------------------------58%---------------- IWD------------------15.4

Alloy #2- 93,5% Pb, 3.9% Sn, 2.3% Sb, 0.27% Cu---85%---------------- 70 deg WD-----------15.4
Alloy #2------------------------------------------------- 71%----------------IWD-------------------15,4

Alloy #3 92.5% Pb, 3.7% Sn,3.5% Sb, 0.25% Cu----48%-----------------70 deg WD-----------15.4
Alloy #3 ------------------------------------------------56% ----------------IWD-------------------13.4

Alloy #4 83.65% Pb, 8.2% Sn,7.7% Sb, 0.45% Cu---79% ----------------70 deg. WD-----------15.4
Alloy #4 ------------------------------------------------61%-----------------air cooled-------------14.3

So in summary the base alloy with almost no tin functioned poorly. Adding tin helped moderately and adding copper to make the tin plus copper percentages about equal to the antimony percentages helped a bit more. However I don't see any alloy that meets my goal of a consistent retention of weight high enough for both my paper punching and pig hunting at velocities of 2200 ft/second. I think my mold's long, heavy and unsupported nose is too heavy for medium velocity 30-06 loads. I've ordered another AccurateMold, # 310-185-L-gas checked with much less nose forward of the driving bands and will give it a try.

Any other comments or suggestions?

thanks- oldandslow

[ku4hx]

How do you get the copper into the alloy? What I visualize is simply pouring a measured amount of copper powder into the pot.

Does the copper actually become part of the alloy or does it float to the top like bullet jackets do? This process is quite interesting to me but I'm totally ignorant of its specifics.

[kbstenberg]

Ku4hx if you go to the stickies there is a couple of threads on Copper. They explain how to, and what effect to your bullets. Kevin

[Hamish]

This will keep you busy for a while,,,,,

http://castboolits.gunloads.com/showthread.php?172475-High-Copper-Alloys-Lets-discuss-this-further

[ku4hx]

Ku4hx if you go to the stickies there is a couple of threads on Copper. They explain how to, and what effect to your bullets. Kevin

OK, thanks ... excellent idea!

[dverna]

O&S

One bullet may not tell the whole story.

The test with 85% retained weight should be viewed as "successful" IMHO. There are jacketed bullets that do worse. Of course that needs to be evaluated relative to the expansion you got. If it expanded to 1/2" and retained 85% it would be a winner.

85% of 180 gr = 153 gr
85% of 200 gr = 170 gr

One "solution" is to go with a heavier bullet if you feel that 2200 fps is as fast as you can go. The heavier 200 gr bullet will give you 94% of 180 gr (170/180 = 94%) if it also retains 85% of its weight.

Don Verna

[popper]

I think you might be interested in the results of 2% Sb/1% Cu/97% Pb/0.2% Sn, WD.

[oldandslow]

casters, 8/2/13

To test each alloy I shot and recovered two boolits and then averaged their retained weight. The higher retained wt.s of alloy #2 and #4 were the result of one nicely mushroomed boolit with high wt. retention and the second being one with poor wt. retention. I realize that two boolits for each alloy is not a good statistical sample but I was looking for trends in an alloy that might justify further testing. I think that I just have to accept the fact that no matter what alloy used I won't be able to retain nose weight/toughness at 2200 ft/second in this particular boolit.

best wishes- oldandslow