WHY, Pin Holes in bullet Base

[243winxb]

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.

[HWooldridge]

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.

[Winger Ed.]

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.

[BK7saum]

Refer to this thread as well.

https://castboolits.gunloads.com/showthread.php?444881-Lee-375-250-cast-bullet-base

[dondiego]

Need a larger sprue.

[Dusty Bannister]

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.

[BK7saum]

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.

[45workhorse]

OP is pressure casting amd not pouring a generous sprue, which is the problem. Either thr 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.

What he said

[243winxb]

" not pouring a generous sprue" this would be it. No puddle at all when pressure casting. Ty every one.

[charlie b]

Both not enough sprue puddle and not hot enough mold/sprue plate.

[brstevns]

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

[243winxb]

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.

[bruce381]

Need a larger sprue.

yep thats it when you pull the mold off the spout let is fill a larger sprue

[stubshaft]

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).

[243winxb]

Refer to this thread as well.

https://castboolits.gunloads.com/showthread.php?444881-Lee-375-250-cast-bullet-base

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.

[243winxb]

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.

[Dusty Bannister]

Have you considered reading glasses to just clear up the sights?

[243winxb]

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?

[Dusty Bannister]

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.

[Martin Luber]

There is only ONE thing you need to look at; the front sight.
Rear sight gets definition from visual depth of field effects.
Regards

[243winxb]

Bullseye pistol shooter back in the 70s. I remember now it works, with good eyes.:lol:

[JonB_in_Glencoe]

I realize you posted...

Not going to cast with linotype again. 1 time test. Standard alloys not a big problem.

But when you posted this, I figure I should chime in with some science for others reading it.


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.

Actually, Linotype (which has 12% antimony) has a melt temp of 459ºF, which is about 100º lower than the melt temp of COWW and 160º lower than the melt temp of pure Lead. Typically the alloy casting temp should be about 100º above liquidus temp. So the pot should be around 560º when casting Lino. Pressure casting shouldn't be necessary when casting Lino, due to the high amount of Tin in it. Casting hotter than necessary might cause other problems, but shouldn't cause those pin holes, but leaving no sprue puddle surely will.

[243winxb]

Lower, good to know. Ty.

[h8dirt]

Shrinkage during solidification. As several others have stated, manage your sprue more carefully.

[oley55]

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?

off subject but these are what I use. different size aperture for pistol versus rifle. I bought both and use them on different shooting glasses so I don't have to screw around getting them in the right spot. Proper sight picture gets difficult if the peep isn't in the right place. They are absolutely amazing, at least for me and I'm mostly blind in one eye and can hardly see out of the other.

https://eyepalusa.com/ "This is particularly useful to shooters who have limited near vision as well as distance vision challenges." (That's a cut n paste from their page and describes me pretty well.)

[GregLaROCHE]

I was wondering if the boolits were all the same weight.

[243winxb]

I tried aperture for pistol years ago, may be something to re-visit. Thank you for reminding me.

I will have to check the weight. I normally check a few before size & lubing. I think i still have some of the linotype lot?

[oley55]

As with all things nothing is perfect. They are amazing for honing all of the usual shooting skills but it's not like we will be wearing them in a self defense situation. So most of my practice is with them, but I still practice without them.

[243winxb]

Bevel base or flat base? Looks like a slight BB thats hard to fill out, unless pressure casting?

This Tarus G3C will not notice the difference in bullets with me shooting it.

Did a quick sample weight check this morning. See photo.