Brass MP Mold in 45 Why am I getting wrinkles

[spur0701]

I picked up a brass 4 cav MP mold in 9mm, it's a MP359-125FB_B_4C_nlg.....am very happy with it and it drops pretty bullets. Since I had such a good experience with I ordered a MP 452-374 hollow point but it seems no matter what I do it'll only drop wrinkled bullets, see below.



I've cleaned it, and heat cycled it both on a hot plate and by casting with it both, at least half a dozen times, and use the same alloy as the MP359 but it won't settle down and cast clean the way the MP359 did.....anyone clue me into what I'm doing wrong? Appreciate any help.......

[gmsharps]

Looks like you may need to turn the heat up a bit. A lot of the brass molds need to be run hotter than iron molds.

gmsharps

[daloper]

Looks like a cold mold. Did you heat cycle it a few times before using? Also do you heat it on a hot plate to bring it up to temp before casting? A hot plate with a circle saw blade on it is your friend.

doug

[Burnt Fingers]

1. Preheat the mold on the hot plate. If it has coils use an old saw blade to set the mold on.

2. Run your pot hot. I've found the sweet spot with hollow point molds to be in the 770-800 range.

[spur0701]

I've been preheating them on a hot plate but am not sure of the exactly temp, and I've been putting them both on the hotplate (the MP359 and 452-374 and the MP359 one cast fine).....the alloy is in a Lee pot with a PID set at 750 and I would swap back and forth between the two.

[daloper]

If you are swapping between two molds, it might be getting cold between it's pour and the next pour. Try just using the one mold to see if you can find the sweet spot to run it at.

[BK7saum]

Also, there was a thread a few weeks ago about similar issue. Caster was cleaning, but maybe re-introducing oil into cavities from the compressed air line or maybe too much sprue plate lube.

But I agree, your boolits looks like a cold mold issue to me.

[gwpercle]

Are both moulds brass ?

When casting with both , side by side , one does fine and the other drops wrinkled ?

This one's a head scratcher...but
Mamma never said making good boolits was going to be easy !

[Bent Ramrod]

Hollow point pins make dandy heat sinks. Turn up the alloy temperature. I’ve also found if I hold the HP pin in a flame until it heat blues, it reduces the wrinkle potential.

[Mitch]

I have 2 MP molds here bothe cast 38s.i to had problems .I found tuning up the heat of the alloy didnt help me much.I would stry ay the 750 on your pid and heat the mold hotter to start then cast vey fast till you get some frosty bullets then slow down a bit.I cast the mp mkolds at 730 on the pid.i preheat the mold hotter than aluminum and cast at a fast pace.thsi way you will fin the sweet spot.

[Greg S]

I think the mold prep is good, heat that sucker up with a full pot and cast fast, non-stop until you achieve what you are looking for. Don't look at what your dropping until you get consistant good looking bullets. I had the same problem with my third mould and finally casted about 6-10 lbs through it to the point it was starting to frost on the lube grooves. I let it cool a tad, dropped the alloy down to 725-30 and it started dropping gems. Once it started, it has been an easy starter like the rest of my molds.

[6bg6ga]

crank up the heat a bit more. Your wrinkled bullets can still be shot.

[Harter66]

I have 1 brass MP . A 462-425 with plain and HB pins .
OMG what a pain in the ASKII that little darling was !

In part it was my location . I lived in a desert at high altitude where rust , oxidation , etc just isn't a thing beyond boiling the solvents out of car upolstery and paint . I heat cycled the mould 10-15 times , 4-5 times before I cast the first blob ......um....bullet . I heat cycled at least once sometimes twice between sessions and about the 8-9th session I started to get good bullets . It was pita enough for me to swear off brass .

Now that I have a mould that casts well , 25 sessions and a move to the green hell later , I see the appeal of brass . It just takes time for the brass to settle down get that all important oxide layer of patina . When it hits it's gold .

My hot plate has a cast iron kettle plate/pot holder depending on its use on the table or stove . So I have a flat plate of pretty uniform temp that once warmed up stays hot . Set the mould on the plate sprue plate down when you start your pot up . When the melt starts to sweat tip the mould to sprue plate up . Do you have a cover (metal coffee can dog house) over the hot plate ? If not , do make one and use it . 350-375 inside the doghouse is a good place to start .

If you have more mould lube than enough to darken the face of the sprue plate or get it in the pour holes it's going to raise Cain with the mould and track all over . Just touch the slip rods on the outside with the mould hot and closed for lube there . Last turn on its side while you flux and warm your ladle or the last 2-5 minutes of warm up . Turn it slide pins up . It's not a perfect system but it'll get you close .

The base/nose pins aren't as hard to keep hot as one would think from reading . Brass will cast slower than aluminum or iron but for with a 750-775° pot it's not enough slower to add an aluminum or iron mould . The brass will over heat and mine shows it up but pulling away on the center bands .

This brass mould taught me about mould heat soak vs hot mould . The darn thing would cast good bases with bad noses , good noses with bad bases and just about the time I'd get the noses and bases talking the bands would be wrinkled or round and frosty .
It's so much better now . I still use the warm up above but can skip the last side turn mostly .

Good luck .

[spur0701]

lots of good info guys, thanks and I'll try again this weekend..........

[Treetop]

spur0701, IMO, this was and is the definitive thread on castboolits.com re: the proper break in of brass molds. It's a long thread but the post that helped me the most was post #53 by Mal Paso. I have used this safe, simple treatment on every one of my brass moulds since 2013. The difference was immediate and profound. My brass moulds now cast beautiful and "fuss free" boolits.

Here is the thread, you may want to save it.

http://castboolits.gunloads.com/show...-Patina-Recipe

I hope this helps you as much as it helped me! I was about to throw my first brass mould away, I was so frustrated! Now, I own 4 or 5 MP moulds and love them. Treetop

[6bg6ga]

I don't agree at all with heat cycling molds as a cure. It doesn't make sense to me. This is a simple process. The mold MUST be clean and to the proper temp. I had a mold once that I swore was a ***. I did your heat cycling out of pure desperation. It did nothing. I cleaned the hell out of the mold with brake cleaner and suddenly I got good bullets.

[cwlongshot]

I was casting with mine last night. Occasional wrinkles before fully up to temp is not uncommon. I found that getting the mold as close to the pot when filling AND careful aim into center of cavity fill stopped all wrinkles.

You can also try pressure filling. But just a hotter por and closer fill combined with careful aim gave me hundreds of perfect boolits.



Every mold is a lil different. Centering the stream for no splash works best for me in HP molds.

Good luck!

CW

[country gent]

One thing that hasn't been mentioned is fill rate if the mould. a slow fill can cause wrinkles and inconsistencies also. I would try this if you can. Heat lead to temp and pre heat mould. Try ladle casting and fill the mould as fast as you can. A pressure pour may even be tried. with ladle up right fit spout into the sprue cavity and turn together give a 3 count and form sprue. Also a well center pour with a full stream of lead from the ladle. Getting good bullets can be done, wrinkles are formed from oil in mould, poor venting, or alloy cooling begore fill is complete a slow fill may allow the latter to happen.

Try a session ladle pouring with a good ladle lyman rcbs and see what happens.

[Boolit_Head]

I've got what looks to be a identical Brass MP mold. Run that thing hot to the point of frosting and just back off a tiny bit. It likes it hot. If I don't preheat it very well with the pins and all suit's almost impossible to cast fast enough to heat it up to where it needs to be.

[flydad]

Quote from Mitch: I have 2 MP molds here both cast 38s. I too had problems .I found tuning up the heat of the alloy didnt help me much.I would stay the 750 on your pid and heat the mold hotter to start then cast very fast l would cast until you get some frosty bullets then slow down a bit.I cast the mp molds at 730 on the pid.i preheat the mold hotter than aluminum and cast at a fast pace. This way you will find the sweet spot.

I have that MP mold and the above advise is right on point. I let mine sit on the hot plate about 15 minutes while the lead in the pot melts. After that cast fast and don't look for about 10 pours . You should be good after that. You can also heat up the sprue plate with a torch, but not always necessary.