Hi everyone,

I'm trying to decide whether I want to cast bullets for my .500 A2. How fast can you push a 600 gr gc bullet without bad leading problems? Do you have any hints and tips to avoid leading?

Thanks

Have a look at Von Gruff's thread 'Slow powders for cast loads.' I have personally fired only seven shots of my load without any leading and accuracy for those was rather encouraging. I have no idea of the velocity but the charge was 35.5gr Varget/AR2208 behind a 220gr cast lead bullet with no lube grooves, gas checked and nose lubed. They could not have been too slow!

There are many factors to affect leading, so its impossible to provide a hard and fast number.

Assuming properly sized bullets for the gun, properly sized and a good lube, you should have little problem pushing them 2200 fps with good acccuracy and no signifigant leading. You might be able to hit 2400 fps.

If you have a fast twist barrel, i.e. 1-10 then it will be prone to leading at a lower velocity. If you have a 1-15 twist, it should be more tollerant of cast bullets.

With my 500 Jeffrey I pushed 600 gr cast 2200 fps with no leading, but accuracy was poor. I believe the accuracy issue was due to the short case neck which resulted in the base of the bullet being in the body of the case. I recomend adjusting your seating depth so that the base of the bullet does not protrude past the bottom of the case neck.

Thanks for the hints, Paul. My rifle is made by A2, so it's probably got a 1:10 bbl from what I've read. I was looking to get near 2000 fps, so you've given me good news. Anything over 1800 fps is acceptable, although I'd prefer higher.

If you want to work out the pressure-velocity for your load the following is somewhere to start. The BHN of your alloy times the common number 1422. This is the max pressure for your alloy. minus 5% for safety and 10% for the supposed sweet spot. In the Lee book Richard Lee gives the formula for working down from a known jacketed bullet load and it is workable for the harder alloys as well. He gives an example of each grain of powder reduction giving a reduction of pressure by 2.5% and velocity by .9%. If you use the load tables to work out the actual reductions for your particular cartridge and the slower suitable powders you will get to what works for it. I used his formula as is for the 404 and it gave me within a few fps for the load it showed should work best for pressure and no leading. It might not give exacts but it gives a ball park to start in.

Von Gruff.

PAUL
im getting a mould made for my 416 ruger, its going to be a 400 gn slug, and im certain that the base of the bullet will protrude below the bottom of the case neck.....do you feel this will effect accuracey in a detrimental way
Daniel

From my experience with the 350 Rigby and 500 Jeffrey, when I had the base of the bullet below the neck of the case, accuracy was poor. With shorter bullets, i.e. those that had the bullet base in the neck of the case, accuracy was good.

I haven't done enough testing to conclusively say that it always holds true. That said, if i was having a mold designed for a given case, I'd design it to keep the bullet base in the neck, even if I had to make the bullet lighter than desired.

I have formed the opinion that cast bullets should sit in the neck and no deeper. This is not based on any testing or reading or anything other than looking at the case design. I am guessing that if the base of the bullet prodtrudes into the case, powder granules will get wedged between the bullet and neck. I have chasen to mimic the original bullet for my rifle - the 215gr RN. But to get the bullet to fit the throat closely, my bullet has ended up a bit heavier. Another point wich may or may not be significant is the 'dough-nut'. It might not exist until actual firing, in which case it would not do the bullet any good.

Leading itself might not occure but flame cutting can! Flame cutting does not mean there will be leading - it's a vapour or at least a finely atomized liquid which will be blown out the bore by escaping gases and the passage of the bullet.

Just my thoughts.

This is what happens to a plain based bullet with too much pressure.


This what happens if there is a gas leak caused by scale in the groove.


The top bullet had a step where the gas check was supposed to be.