muzzle flash said:
How about sharing some of your load data and results. I am just starting to tinker with cast in .303,7.62x54,30.06,7.5x55 and 7.62x39. Anybody using fillers?
I used to use fillers, but the general current wisdom coming from the uber gurus in the Cast Bullet Association is that they aren't necessary with proper loading and do raise a possibility of ringing your barrel. I used to use Super Grex, but I don't think you can get it anymore. Ken Mollohan wrote quite extensively on the use of fillers if that interests you, and I believe he still hangs out on the cast bullet email lists.
I have come to agree with the most current views on fillers, although wax wads are giving a lot of high power rifle shooters good results in rifles with difficult chambers.
Aside from Ed Harris's Does-All Red Dot Load, I don't think asking for loads is too helpful. Unlike jacketed bullets, there are other factors in the mix when you're doing the cast bullet thing, and they play a major part in performance. My opinion, for whatever it is worth, that the following are the three major things to getting good performance out of cast bullets:
- Bullet fit to ball seat/leade
- Bullet fit to ball seat/leade
- Matching bullet hardness to load operating pressure
If you have a good bullet fit, you won't need fillers or wax wads. If you don't have that fit, then COW or something like Super Grex will help prevent leading. Pressure matching addresses the same issues. And so... the powder and charge operates in conjunction with bullet design, lube, amount of lube... and of course bullet hardness.
To each his own, but I just look at the starting loads in the Lyman book and then get on with it - after measuring up a chamber cast. Quickload looks like the best way to go, and I'll probably put that on my shopping list pretty quick.
HEAT TREATING WHEELWEIGHTS
Heat treating wheel weight alloy is both controllable and predictable ie: It is possible to heat treat wheel weight bullets and predict the final hardness to be achieved.
Hardness does not increase until the quench temp (after a ½ hr heat soak) reaches 420 deg. F. as measured with a digital thermometer shaded from any direct radiant heat.
Temperature vs. Resulting Hardness
410 12 BHN
420 15 BHN
430 17 BHN
440 23 BHN
450 29 BHN
Conclusions:
Exceeding 450 did not cause any significant increase in hardness.
460 deg was very close (read that too close) to the plastic deformation stage of the alloy
OPTIMAL HARDNESS FOR OPERATING PRESSURE OF LOAD
Tensile strength of lead/lead alloys = BHN x 480
Best bullet performance is usually at pressures between 3 and 4 times
Tensile strength. I don't how to make a table appear properly in here, so you'll just have to look at it and figure out how to reconstruct it - not hard, the board software just takes out a bunch of the tabs and formatting.
ALLOY BHN TENSILE STRENGH (PSI) TIMES 3 GIVES TIMES 4 GIVES
MIN. CHAMBER PRESSURE (PSI) MAX. CHAMBER PRESSURE (PSI)
PURE LEAD 5 5(480)=2400 7,200 9,600
1-20 Pb/Sn 10 10(480)=4800 14,400 19,200
WHEEL WEIGHTS 12 12(480)=5760 17,280 22,040
LYMAN #2 15 15(480)=7200 21,600 28,800
LINOTYPE 22 22(480)=10560 31,680 42,240
HEAT TREATED WHEEL WEIGHTS 30 30(480)=14400 43,200 57,600