venting problems?

[rusty marlin]

I finally bought the Lyman 457122, 330 grain HP, and got around to casting with it this weekend.

Alloy is Lyman #2 (from Wheel Weights) cut 50/50 with Pb.
tin 2.73%
antimony 1.80%
arsenic 0.11%
lead 95.36%

casting temp was 625+/- 25 degF.

After the initial warm up the bullets were looking GREAT, but after 10 or so I was getting poor fillout in the corners. I'd stop and scape the faces with a razor blade and get good results for a few them get poor fill out again.

Is it possable the mold just isn't venting properly after getting used and maybe the vent lines are cruddy? They are VERY fine as was wondering what the best way to open them up a .001 or .002 would be.

[Wayne Smith]

Do you have a dentist's pick? That's the most aggressive thing I've used, files scare me.

[deltaenterprizes]

Edge of a single edged razor blade

[rusty marlin]

This is the direction I was headed.
Thinking of useing a TiN coated utility knife blade. The other idea was a carbide tipped scribe.

[leftiye]

Carbide scribe is the cat's meow. Vents can be larger than you'd expect and not make "whiskers." Not to say that they can't be overdone, so use moderation. I have used a triangular file with a sharpened corner.

[hyoder]

I would try casting at a higher temperature - 725 or so - and see if that will help. You might want to make the increase in steps - 675 then 725.

[rusty marlin]

Oh baby! I got BEAUTIFUL BULLETS! :mrgreen:
First I tried the razor blade, not agressive enough, then the carbide scribe, not agressive enough, then I used a very small, dead sharb 60deg HSS threading tool and using it like and engraving point dug the grooves on one side deeper by a few thou. Then went over all the edges with a hard stone to just break the edge. Loosened the sprue plate screw 1/16 turn and started pouring at 800F. A touch hot but no frosting, but the sprues where taking a good 10 seconds to solidify. So I backed it down to 700 and poured till my heart was content. I'm a happy caster tonight! I've never had 95% keepers, I'm absolutley giddy I tell ya.
:drinks: