Need some help with an MP mold/newbie caster

[CGT80]

I tried out my MP mold yesterday. It is a 452 270 SAA 4 cavity brass with all the pins. I am running what should be WW alloy. I am going to build a mold oven to preheat my molds. I got the bullets to release from the brass easily, but they were getting stuck on the pentagon shaped pins. These pins have rough machining marks. The pins may have been cut across the pin rather than down the long side so they have little serrations on them. It looks like a file, and I would imagine the roughness is holding the bullet onto the little serrations. The part that would form the very tip of the bullet is also cut a bit rough so that even a frosty bullet with good fill out had little wrinkles or indents in the nose of the hollow point.

The smooth round hollow point pins dropped a little easier, but I didn't get to use them much. Solid point come out nice too.

Are all of the pentagon pins that rough or is it just mine? Even when I got the mold hot enough to cast frosty bullets, I was having some trouble dropping the bullets off the pins. I ran my melt from cool to almost all the way up on the little lee drip-o-mattic. Should I be using a release agent on the pins, or just wait till I gut my oven built so I can keep the mold warm? How hot do you guys like to have your molds before casting?

I like the MP mold. A cast bullet measured out at 0.453 as advertised with one small spot at 0.454. After being sized it was 0.452 +/- 0........That's right, it was round unlike the bullets from my RCBS mold. I used digital calipers for the measuring-I know-not quite as accurate as a micrometer.

Off to the shooting range I go.
Chris

[Roger Ronas]

I also noticed the machine marks on the penta pins and I took some 600-800 grit emory boards and smoothed them up till the marks were gone. I have not done any casting before or after this mod, but as others had mentioned the marks and some difficulties I did it as soon as I received the molds. Also on the round pins you can use 4aught (0000) steel wool to smooth them up also.

Others will chime in I'm sure,

Roger

[MtGun44]

I have several of the penta pin molds, all were reasonably smooth, but I polished
them down a bit. Use some moly or graphite on the pins. With time they seem to build
up a slight oxide coat that helps release.

Bill

[edler7]

I'd bet your pins aren't hot enough. I had a devil of a time getting my boolits to drop from the pins till the pins got really hot. At that point, the boolits almost jumped off when I opened the mold. As soon as the pins started to cool a little, the boolits started sticking again.

I find when the pins are hot enough, I get about 5-6 good fills on the mold...then they start sticking again. I put it back on the hotplate for 2-3 minutes and it's good to go for another 5-6 rounds. I've tried to cast faster, but I can't seem to retain enough heat in the pins for very long. I don't keep the mold open any longer than necessary. My alloy temp is 725 degrees and the alloy is 50/50 wheel weights/lead.

This was in an unheated garage during the winter...maybe now that warmer temps are here it won't be such an issue....haven't casted anything with it for a couple months.

[buyobuyo]

I had the same issue with the penta-pins for the last MP mold I received. A 454-200-HP. I tried 0000 steel wool with no difference in how they cast. Today, I took a file to the penta-pins to eliminate the tooling marks. Now the boolits drop off much easier. I think I will need to go back over the pins with some fine grit paper or stone to get them smoother. At least now they are smooth enough that I can cast through multiple pots. Before I wouldn't make it though a single pot before I got so frustrated that I wanted to hurl the mold out the window and gave up before I actually did.

[CGT80]

Thanks for the info guys. I think I will try cleaning up the pins. I am also going to make an oven for my mold, to sit on the hot plat that I ordered. I have some 3"x6" rectangular steel tubing that is 1/4" thick. I think I will weld some 1/4 plate on the back and put a couple spacers inside so that when I reverse the pins, the mold will sit flat on the spacers with the pins in a slot. My thinking was that this would keep the mold to a more even temperature and then I could also put my ingots on top to warm before going into the pot.

Does anyone have a particular temp. they like to preheat the mold to?

I shot a competition today and had some great times on the stages. I went through a couple hundred 9mm rounds with J-word projectiles. I ran 150-200 rounds through my 460 revolver. Only about 25 of them were boolits (228gr .452 from on RCBS mold-round nose) but they shot just as well as the mass produced variety. As soon as I get the hot plate I'll try making some more pretty silver projectiles for the big boy.

They have been mining the range for lead, but I didn't see anyone out there today. I am going to see what price my buddy can get me for clean lead. He works at a local scrap yard that buys clean lead for 45 cents per pound-he hasn't found out what the sale price is yet. They pay 19 cents for wheel weights, but he didn't know if there was zinc mixed in, and I would prefer to start with relatively clean lead-we'll see. Even if I buy range lead ingots here for a buck a pound, it will still be 1/5 the money, or less of buying commercial cast.

[MikeS]

I have some thermometers that are only 2.5" long, and when I preheat my moulds I stick one of them into one of the cavities of the mould. I find that when the thermometer is showing 250F that the mould is about ready to cast. I'm sure the mould is actually hotter, as there's as much or more of the portion of the thermometer that's important, sticking out of the cavity as there is inside the cavity, so while it's not giving me the proper temp the mould is at, it's a reference point, so when it says 250F I know the mould is ready to cast. I find that if the thermometer is showing 300 - 325F that the mould is actually too hot, and it can take almost 30 seconds or more for the sprue to harden.