Excellent mold from Accurate - but need some help

[DrCaveman]

I tried searching for answers, but everything was too general. Ill try to describe the situation as thoroughly as possible.

Got my new Accurate 453-200h. It is an h&g68 clone, for 45 auto, 4 cavity, brass. Two words: love it. Not sure if i can go back to my lee molds, but heck i still gotta get my rifles fed.

Now that i realize how awesome and consistent boolits can be dropped from a mold like this, my QC level has increased significantly. I am rejecting a lot of boolits that are better than ones i formerly shot. Why? Because now i see the real potential. Maybe ill loosen up if i dont see a marked difference in accuracy or leading.

So it baffles me why one cavity is so resistant to produce perfect bases when the other three are so gal-darn consistently muy perfecto!

Here is what i have done:

Upon receipt of molds, i cleaned them well with warm water and dish soap. Rinsed very thoroughly. Hand dried with paper towel. 30 minutes later, i set the mold halves on my flat-surfaced hot plate (no coils on top) at the same setting i use that melts beeswax in about 15 minutes. So i figure maybe 180-200 when the stat finally kicks off? I didnt want to warp them, but i thought a few heat cycles would be good.

Did this three times, letting the blocks slowly cool to air temp between each heating.

Finally attached the handles as the pot was warming. Applied a light coating of lucas semi synthetic 2-cycle oil to the mold faces, alignment pins, and sprue plate bottom.

Once the pot was up to temp the mold needed a lot more heat than i am used to with my aluminum molds. Wrinkled boolits for a bunch of pours. When i got the mold to temp, out dropped the best looking boolits i have yet cast. Excellent bases, sharp features, desired diameter, proper nose profile...what more could i ask?

Well unfortunately the cavity closest to the handles does not get the same consistent base fillout as the rest. When i use a routine that gives me perfect fillout in the first three cavities, i get about 80% reject from cavity 4

Ok i tried starting my pour at cavity 4, no difference. I added a little tin no difference. I bumped up alloy temp no difference.

I poured cavity 4 as a single cavity (no lead in other cavities). Success!

Tried pouring real fast into cavity 4, tilting mold so overflow spreads to other cavities in that style. Now cavities 1&2 have incomplete bases, but 4 is good.

Tried pouring with a very large sprue puddle. Like, overflowing both sides of sprue plate and 1/8-3/16" thick when set. This worked the best but still not 100% rate of fillout in cavity 4.

So thats about where i am at tonight. I realize i could have contacted directly the mfgr but i wanted an opportunity to state how excellent Accurate Molds are, and how darned pleased i am with mine.

I further figured that the collective wisdom of this place would get me running straight without having to distract Tom from making such great molds for us.

Am i letting my mold temp fall to far? If so, why am i getting such good results out of cavities 1-3? Maybe something unique to brass molds that i dont understand?

Im ears here, i am sure this is a solvable problem. Thanks

[runfiverun]

adjust the sprue plate tension.

[DrCaveman]

Ummmm... That is something I didn't try. I did in fact visually check the sprue plate contact with mold blocks and it looked ok

Never dawned on me to just try snugging up the sucker.

I feel dumb. Thanks for the tip. Ill get back tomorrow eve with follow up

[hermans]

I have the 45-230H mold from Tom, the same as yours, brass 4 cavity, and I just love casting heaps of beautiful shiny boolits with it.
Personally I do not think that there is anything wrong with the mold, or the alloy, and it seems like you are doing everything just about right. What I have found with my different brass molds, is that they each have a different sweet spot in terms of casting temperature and your casting rythm, so the trick here is just to find your mold's sweet spot in terms of the above.
Mine I have to cast really fast and hot to make all the cavities fill out properly, and than every 4th cycle I cool the mold by pressing it down on a wet towel for about 5 seconds. Maybe you could try this, it sure works for my mold.

[Bullshop]

"adjust the sprue plate tension."
"Never dawned on me to just try snugging up the sucker"
I dont think he nessisarily ment to tighten it.

[tomme boy]

Yep! Try loosening it first. The plate should fall freely if the mold is turned sideways.

[Bigslug]

I'm pretty sure it was the Lucas oil (or any other) that was giving you bad pours. Vaporizes when the hot metal hits it, keeps the mold from filling, and it takes a looooong time to cook out and get back to dropping clean. My 5-cavity 453-230F starts making perfect boolits from about the third or fourth pour starting from room temperature - aluminum molds don't take that long to heat up.

A little Bullplate across the top of a mold right after cutting the sprue but before dumping the slugs is the only oil you MIGHT need to prevent streaking across the top.

But as mentioned, try a looser sprue plate. Lead has to get in, but air also has to get out.

[gunoil]

turn ya lead heat up, like bigslug said no oil.

[Springfield]

I've tried 5 different brands of 2-stroke oil and none of them has ever caused a problem. Still have lots of Bullplate, just testing in case it ever disappears again. Loosening the sprue plate is good advice.

[DrCaveman]

Okay, the solution was simple. Like his lube. Runfiverun nailed it, all cavities are pouring equal now.

And, as bullshop Tomme boy & springfield suggested possible, loosening the sprue made things right.

Thanks guys and i hope to not repeat such a simple question.

Accurate Molds rock!