9MM Lee 356-120-TC ,Virgin Rotometals Linotype, pressure casting, Lee 10 lb bottom pour spout. (Linotype is for a test)
Why the pin hole on almost half of 100? Trapped air?
Dropping into mold gives poor fill out.
Scrap, WW & a bit or linotype doesn't give me this much trouble, with this 2 cavity mold.
Have 50+years casting with iron molds & fewer problems. This is 3th Lee.
The entire bullet looks like it's not filling - unless this is designed as a bevel base. I would say your sprue doesn't have enough material to allow the base to fully fill out.
Looks like shrink holes from the ally being too hot.
If you're not getting a good fill out- the mold is too cool, or you need a little bump of Tin in the alloy.
Possibly both.
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In life: We are given tests, and learn lessons.
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Refer to this thread as well.
https://castboolits.gunloads.com/sho...st-bullet-base
Need a larger sprue.
Look closely at the bases of the bullets and you will see incomplete fill as shown by depressions in the bases of several of those bullets. If this is a Lee 6 cavity, you might change your method of filling the cavities. I get better fill out if I pour, stop, move, pour, stop, move, etc until the cavities are all filled. That makes sure that the hot alloy goes directly into the sprue funnel. If you start pouring and drag the mold under the nozzle, the alloy splashes off the side of the sprue funnel and can trap air in the cavity and you get voids and gaps.
I use a well heated mold, alloy at about 720 and move quickly to fill and empty the mold. If this is a 6 cav mold, your 16 or 17 casting cycles is not enough to get a tempo going and keep the mold at temperature. If you are using 2 cav mold, that is a different critter.
OP is pressure casting and not pouring a generous sprue, which is the problem. Either the lead is freezing in the spout or he is not leaving the valve open long enough as the bullet cools. There is no liquid alloy for the bullet to draw and it leaves a void.
Last edited by BK7saum; 07-22-2022 at 08:48 PM.
What he saidOriginally Posted by BK7saum
" not pouring a generous sprue" this would be it. No puddle at all when pressure casting. Ty every one.
Both not enough sprue puddle and not hot enough mold/sprue plate.
Like he said. Had the same problem some 50 years ago when I first started casting. Need that sprue so bullet can pull lead down into it to completely fill
The 12% antimony in the Rotometals linotype is going to need more heat then my normal alloys. I didn't allow for that.
Should have left pot temperature setting at maximum, till i got frosted bullets. Then adjusted down.
yep thats it when you pull the mold off the spout let is fill a larger sprue
Sprue hole is too small. I usually open up the sprue holes in my molds so that they fill more rapidly AND make sure that I leave a good size puddle (sprue).
Old enough to know better, young enough to do it anyway!
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Great link. I should have did a search first. It's a very recent post.
stubshaft - Opening the sprue hole can work, but last thing to try, I think. I had to open a Saeco 38 pistol mold to get fill out years ago. Opened the Lees 10 pound pot spout hole at the same time. Sill using the same Lee pot.
Not going to cast with linotype again. 1 time test. Standard alloys not a big problem.
Guess what, the G3C Taurus doesnt notice the difference between pin hole bullets or good ones. Same 6.5" accuracy @ 25 yards.
But I will mostly blame it on my 77 year old eyes. I don't see the rear sight clearly. Adds vertical.
Have you considered reading glasses to just clear up the sights?
Have 3 different pairs of glasses. Eyes no longer change focus on target, front & rear sights. Young eyes easly move between the 3 distances. Old folks stuck at 1 distance.
How i understand it?
Sight picture is everything. If you can not have a clear focus on the handgun sights, you can not tell if there is equal light on each side of the blade or the sights are level across the top. If you have a clear focus on the target you can easily see how far off the bullseye you are hitting.
There is only ONE thing you need to look at; the front sight.
Rear sight gets definition from visual depth of field effects.
Regards
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