Torn driving band out of the mold

[RDub]

http://i48.photobucket.com/albums/f218/rafswede/DSC01784%20-%20resized_zps1budcgdt.jpg~original (http://s48.photobucket.com/user/rafswede/media/DSC01784%20-%20resized_zps1budcgdt.jpg.html)

Hello
This is a boolit from an RCBS double cavity 38 cal SWC mold. This happens with one cavity, not both.
Alloy is 10%Tin/Lead. Casting temp is around 650°, but experimented with cooler and hotter temps while trouble shooting this. This occurred at all temps.
Cooled the mold down, wiped out the cavity with a Qtip and some rubbing compound. Cleaned and applied some Mold Release spray. Still had torn bullets.
When a pour is finished, I notice the mold doesn't open up easily. I have to coax it open and then have to tap a few times for the boolits to fall out.
Also noticed that not every pour is the same. Some pours the bullets are well filled out, then some the boolits aren't filled out well.
This is looking like an alloy issue, but thought I would run it by here and see what you guys think..
Thanks

[Shoot66]

Something similar happened to me with a Lee 358-105 SWC while running at 740°F. I cleaned the problematic part of the cavity with a tooth pick and slowed down. That took care of the problem.

[randyrat]

Scrub the inside of the cavities with tooth paste and baking soda or Bar keepers friend or Ajax or similar product , I use a Tooth Brush. Then rinse it out and wash it with a strong dish soap and rinse real good. You will then have a smooth casting mold.
It may be temp and high Sn Tin content and your running too high of Temp for that alloy

[Cap'n Morgan]

Poor boolit design. The top of the crimp groove, together with the flat front band, form an almost square groove profile making the boolit prone to stick in the cavity. Keith design or not, mold grooves should have at least 20 degree included angle to ensure proper release.

I would try waiting a little longer before opening the mold. Also, if the boolit hangs in the same mold part every time I would check for any nicks on the edge of the front band cavity.

[44man]

That usually happens when the lead has not fully hardened and there is a burr that catches it.
Might very well be too much tin and a lot of good advise was given.

[Hickory]

This happens when the mold and the lead are
too hot and the mold is opened too soon.
In you case it could be any of the above also.

[runfiverun]

I'm thinking like post number-4.
it sounds like a light burr holding on to the drive band.
casting slower [waiting another 2-3 count] and letting the boolit set up harder could help.
but the sticking issue could be as simple as not enough draft angle and letting the boolit shrink those extra 2-3 seconds can make all the difference.

[Ed_Shot]

This happens when the mold and the lead are
too hot and the mold is opened too soon.
In you case it could be any of the above also.

+1 Things are too hot.....slow down.

[country gent]

I would check for burrs and rolled edges, a q tip lightly ran along the edges if fibers are pulled out there is a light burr. look at it under magnification if possible to see the surface better. A rough or chattered surface can cause this also. Heat to high can also cause this as mentioned above. Ive seen alloies with High antimony pull bands tin shouldnt do this as much. I would look at the mould to start with. You might try lightly rubbing the edges with a piece of wood ( bamboo skewer, popcycle stick, piece of small dia dowel) on the corners to pull burrs and smooth edges. No abrasives are needed for this just the wood grain.

[mdi]

I think if you alleviated the "sticking" problem, the ding would go away. I have had molds where the bullet would stick and opening would occasionally mar one side of the fresh bullet. I think you've been given a few good ideas on how to make your bullets drop easier, and I've used Comet and light oi to clean a few cavities (just like lapping, but Comet is not as abrasive...). BTW, I use nothing in the cavities, just brake clean before casting...

[JonB_in_Glencoe]

R,
I don't think it's a alloy issue, but 10% tin seems like a waste...but that's none of my business.

The first 2 things I'd try...
Don't open the mold as soon, I need to run some molds hot, so your issue does come up, in those cases. I cut the sprue and then wait a few seconds to open the mold. The second thing is, when I run a mold 'hot', is to have a small fan moving air over the boolit drop area...I will hold the mold in that moving air for those few seconds before I open the mold.

you mention some fillout issues, well, A hotter mold fills out better. Which is why I took the time to comment the above two hints/tips/tricks.

[RDub]

Hey
Thanks for the excellent replies.. I'll take another crack at it this weekend and see what happens.

[Leadmelter]

I have had that mold since 1980's. Never had that problem. Too much heat and tin?
Leadmelter
MI

[44man]

10# of lead with 1# of tin is rather expensive. Last tin I bought was $14 a pound. Then I lucked into a big pile of 50-50 body solder for $5.
My revolver boolits are WW and I never add tin but for accuracy I will put 19# of WW metal in the pot and add 1# of stereo metal, tin and antimony rich. Makes beautiful boolits.
I suck at math so can't work percentages.
For BPCR I used 20 to 1 and 30 to 1, never seen a difference but when I tried WW, I got leading, why I don't know unless the lube is wrong.
I read about the glory of SPG, splurged on it and got the last 10" of my barrel fouled so bad I had to use a soaked patch to get through, blow tube failed. I could not give the rest away at the shoots. I then bought some other lube, full of moly or graphite, must have been mostly paraffin as it broke out of grooves. Shot for junk.
It gets too expensive so I made my own lube and it worked better.
It is best to be simple so a dime a shot can't be beat. Seems the primer is the most expensive.
I made extensive tests with lubes in revolvers and Felix beat everything I could lay my hands on. Mention goes to LBT Blue Soft, MML, Satan's lube, CR but lead me totally away from Alox in any form. Yes I cut my teeth with Lyman 50-50 long ago but even it is not that good.
My problem was not so much leading, it was accuracy or lack thereof.
I use hard lead because soft gives me fliers. Even air cooled WW metal with a GC. Anneal the GC and air cooled will shoot better. 50-50 PB is sad, needs a GC and oven hardened.
I soften the nose on a hard boolit if I need expansion. I would not be shooting pure with tin from a revolver unless BP is used.
I have made all my molds for the big bores PB, hate the cost of GC's. I made them work and with a scope from the bench have been down to 3/8" and some to 1/4" groups and many under 1" to 1/2" at 100 yards.
I taped a 12 ga shotgun shell to the 100 yard paper and centered it with the .500 JRH, Ultra Dot from the bags.176110 440 gr PB at 1350 fps.

[EMC45]

Try "burnishing" the offending area with a tooth pick with red rouge on it. I have done this to several Lee and Lyman molds. It does the trick for a stubborn or "sticky" cavity. It has enough "umph" to polish the problem area, but not too much to damage the mold.

[Wayne Smith]

Drop your tin to 2-3% - not only will it be cheaper but your alloy won't be as brittle.

[Four-Sixty]

I see you say too much tin, but I have that problem when using reclaimed shot due to the high antimony content.

Just focus on how much effort it takes to break the sprue before opening your mold. This will give you a good sense as to how much your boolits have set up... or not.

[RDub]

Some more thoughtful ideas.. Thanks
I got a bunch of tin back when it wasn't so spendy.. Seeing how much it is now, I'll have to conserve more.. So this weekend I'll dilute the mix down with lead to about 5%. Never had a problem with this alloy in other molds. I'll take a good look at the offending cavity with a jewelers glass and go from there.
Thanks again.

[OS OK]

44man...Heres what the calculator says about the 19# Wheel weights and 1# of Steroetype...I imagine they'll heat treat well too with the arsenic in there.





Mixed..... Alloy.....
Tin %...........
Antimony %...............
Arsenic %...........
Copper %..............
Silver %...............
Lead %.............
Weight..........
Est. Hardness


............................
.78
3.55
0.24
0.0
0.0
95.4
20










12.1

[shoot-n-lead]

Rub that cavity thoroughly with the end of a wooden popsicle..works wonders to remove burrs.

[44man]

OS, thanks. I wrote it in my book.

[Strtspdlx]

I don't think that lower driving band is supposed to have a rounded top edge. I'd say run your melt at 700-800 I run it at 800 until the mold gets hot then I back it down to between 700-750. Mold temp looks about right. Maybe slightly warmer. And increase flow of spout if using a bottom pour. Running the melt hotter should help shrinkage when it cools and help releasing. I have a square lube groove mold though and it isn't fun to try and get Boolits to drop without disturbing something.