View Full Version : Mihec HP issues!?

12-05-2011, 12:34 PM
First time with a mihec HP this weekend. Great mold, and I'm lovin' it. Had some HP fillout issues, though, and thought I'd ask.

I typically use base fillout as a gauge of what kind of reject rate I'll see. I was disappointed when I finished and started culling misfits. I was expecting 70-90% keepers, but I noticed the HP cavity on about 1/3 of my boolits wasn't filling out properly. The front edge was fine, but they either had small pits deep inside, or the bottom of the HP cavity would not show the pin detail around part or all of the circumference. Quite a few of the HP's would have looked fine if I didn't know what the pin looked like, but the cavity was spherical at the bottom (tip of the pin) , not contoured with a little flat like the pin. It looked like the lead shrunk away from the pin. A couple things could be at play. I was using straight WW. Also, when I first started, I was anxious and got started before the pot had stabilized. I started noticing some finning around the HP pin, and checked the temp. I had to back off a little. I had been casting at 875 deg. The last 3/4 of that pot and the next one, I ended up at 780-800 or so. The HP deformity seemed to be random throughout the session. I'll try a little tin next time, but do you think pour technique caused it? I didn't use the guide, due to the pins sticking out the side of the mould. I had a little angle so the sprues ran off the front end of the mold, but it wasn't much <5 deg. or so. I'm using a Lee 4-20, and the stream doesn't seem too forceful. I hold around 3/4- 1" under the nozzle. I don't hit the hole full on every time, but when I miss a little, I still get good base fillout. Could that be the difference?

Any thoughts would be appreciated. You've already saved me a lot of hassle.


12-05-2011, 12:58 PM
Did ou preheat the mould? How many fill cycles per minute? Brass moulds need to be run pretty warm, the mould temp not the pot temp. Brass also needs to be run fast so it doesn't cool too much between pours. The pins cool faster because of the low mass they have.
Some moulds prefer the lead poured at an angle into the cavity. That is something to play around with. You may want a stronger lead datream so the cavity fills faster, again something to experiment with.
I also am assuming you cleaned the pins off very well of any oil. If not, a pot full should have burned off any remaining oil but a cleaning is never a bad idea.

HP moulds tend to have a learning curve to them. Try some different things and see what that particular mould wants. my Mihec 359640 casts beautiful HP bullets with little effort.m some are not fully filled out on the nose or have a small imperfection in the cavity but my guns doesn't seem to care. For 25 yard handgun shooting you might be amazed at the lousy looking bullets that can shoot pretty well. Don't condemn your bullets by eye alone, let the gun the will be shot in tell you what it thinks.

Hope this helps.

12-05-2011, 01:20 PM
I have a couple of HP molds, You have to run them HOT to keep the pin hot. A little tin helps also. Yes there is a learning curve, The first time I tried to cast a mold that was hollow pointed, I about tore my hair out.

12-05-2011, 01:32 PM
A little tin helps just about any HP design mold if you are using straight WW !
An extra 1-2% is all you might need.




12-05-2011, 01:35 PM
how do you add tin

12-05-2011, 02:12 PM
Those are sure some pretty boolits there GLL!

12-05-2011, 02:19 PM

Yes, I just got a hot plate to preheat, and it worked very well. 2-3 cycles is all it took to stop wrinkly boolits. I cleaned the mold well before I started, including pins. I timed myself, and with a 5 count after the sprues solidified, I was getting from 4-8 boolits /min. I'll have to try shooting some of the "rejects" next time. If they shoot, I may have been able to get near 90% good ones this last time. Might be the once in a while boolit that stuck on a pin. A few of those took several seconds to get off. That could have cooled the pin, I guess. I'll try a little tin next time , too. I might try a little less pot temp, and faster cadence. You 're right, I need to have some conversations with my guns. Doesn't happen enough, I say.

Some rejects, yes, but a very pleasant experience. Once you get rolling, it's hard to stop. I dreaded reaching the end of the pot. Hard to believe a guy can get great HP's at that rate of production. I have only used the Lyman single cav's up until now.

GLL, nice HP's. That's what I'm shooting for. :)

Thanks for the help!

12-05-2011, 02:21 PM
Sorry, you may not know I have a 4 cav. mold. A little more than one fill cycle /min. on the time.

Iron Mike Golf
12-05-2011, 02:48 PM
+1 on other's comments.

1. make sure the pins are degreased. Use care in appling lube to the pin's sliding parts so there's no excess to migrate to casting sirface
2. Make sure mold is hot. I need a hotplate. The edge of the pot is not hot enough. Pre-heat to the point of the mold being too hot.
3. I cast as fast as I can. A little frost does no harm
4. Keep a propane torch handy so you can give a quick shot of heat to the pins.

12-05-2011, 05:12 PM
I am running a 2 cav Mihec HP mould and get way more than 1 fill per minute. I am probably closer to 4.
Don't count to 5 after the sprue hardens. As soon as I see the sprue get hard I cuti it and then dump. That extra time isn't doing you any good. With the sprue lube he includes swabbed very lightly on top of the blocks lead smears are not an issue.
I also use a small amount of lube on the pins that extend out from the blocks. It keeps them sliding quite smoothly.
Don't race when casting but a good quick cadence is important. Don't stop to inspect bullets or add things back into the pot. This is where mould temp varies and you get bad bullets. It is all about finding a rhythm that works for you, you pot, and the mould.

12-05-2011, 05:31 PM
Using a LEE six hole in 200gr 452 boolits I always cut sprue when it turns grey and invert mold over pot to dump sprue into melt then open mold over folded cotton toweling and drop the boolits. No extra time and the pot lasts longer with the hot sprues going back in immediately. With a two hole I use gloved hands to cut sprue and catch it in glove and put back into pot right away.

12-05-2011, 06:36 PM
Hmmm Thought I needed to keep the lube off the blocks except for the plate hinge. I'll try it tonight. Lower pot temp will help, too, I think.


12-05-2011, 06:48 PM
I put lube on the topic the blocks, the alignments pins, and on these moulds in particular, the sliding pins that go thru the locks. Keep the amount on the tipoff the locks to an absolute minimum. Getting it in the cavities will give some bad bullets.

As for putting sprue back into the pot fit away, if it doesn't slow you down then fine. I think some people get into a too slow rhythm because they are farting around with things like that rather than casting. A brass mould requires is different, as is the Cramer style. The brass can tend to want a faster rhythm to stay hot enough and the Cramer style slows things down just a little because you need to turn the locks over, make sure the bullets fall off the pins, and make sure the pins move back into the block before closing the mould. All of this seems minor but a few seconds here and there can mean you lose mould temp.

12-05-2011, 06:51 PM
When I was looking to prevent torn bases with hollow point molds, it was just too slow. I had to sacrifice some base to gain in the nose. Very common to try to run them too slow. Also, if you have a ladle, try ladel casting. That was the only thing that saved my 500 grain 50 cals. Even with a ladel I still had to sacrifice some base to maintain fill out. Pot temp did not seem to help much, but cadence and the ladel were really my saving grace on this one.

12-05-2011, 08:21 PM
I have had excellent results with my Mihec Cramer style bullet moulds.

1 - I use Mould release on the tip of the pin.
2 - I lube the pin shafts with Bullshop Sprueplate lube (as well the alignment pins) FOLLOWING the directions.
3 - I cool the sprue with a manicurists fan for two seconds before cutting sprue
4 - I run my metal at a measured 750 degrees.
5 - I run 20/1 for hollow point bullets (lead/tin)
6 - I preheat ALL moulds with a hot plate and consider this a MUST.

I get almost NO rejects and great expansion.

There IS a learning curve to hollow point moulds. You MUST actually cast a number of different times before things start working well.


12-08-2011, 11:56 AM
Hi Gang,

Thanks for the info so far. I thought I'd post some pics to see if you or anyone can say they have seen and fixed the problem I'm having. Seems the straight WW bullets cast with a 3-4 second wait after the sprue cools (780-875deg.) have a roughly 25% fallout due to the HP issues pictured.

The 50/50 Pb/WW +1% Sn cast as fast as the sprue cools (750-790 deg.)had almost a 75% fallout for the same issues. Not apples to apples, but it's what I have at the moment.

A trip to the range will tell if I can use them all, but I would probably hand sort for practice/short range, and best ammo piles. With all the positive reviews, I can't help but think I can get this thing working near 100% if I find the right combination.

50/50 fast cast good and rejects
http://castboolits.gunloads.com/imagehosting/thum_204334ee074881699e.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2910)

http://castboolits.gunloads.com/imagehosting/thum_204334ee0749d29507.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2911)

http://castboolits.gunloads.com/imagehosting/thum_204334ee074bfb7d7a.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2912)

http://castboolits.gunloads.com/imagehosting/thum_204334ee074ceaed01.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2913)

straight WW slow (3-5 sec after sprue cools) good and rejects
http://castboolits.gunloads.com/imagehosting/thum_204334ee0754ec7ab3.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2914)

http://castboolits.gunloads.com/imagehosting/thum_204334ee075592f288.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2915)

http://castboolits.gunloads.com/imagehosting/thum_204334ee07579aa6fa.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2916)

http://castboolits.gunloads.com/imagehosting/thum_204334ee075856ac69.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=2917)

Don't know if you can see the difference in definition in the HP cavity, but it's about the only defect I am seeing other than occasional flashing/finning around the pin. Maybe I'm being too picky, but I like the whole package and will keep trying to get it.

Again, any help will be appreciated.

41 mag fan
12-08-2011, 12:09 PM
I never had any trouble with my Mihec mold. It's a 450gr .503 2cav mold.
My pot temp never goes above 675*.
I'd have boolits hang up on both my round and penta pins. Light tap on nut that holds handles togather is all it took to get them to release.
You use any lube on the top of your mold, due what NOE recommends, fill cavities first then use the lube, then dry off with q-tip. That way none migrates into your cavities.

12-08-2011, 12:40 PM
I prefer softer bullets than straight WW's for hollow points. However, the lack of perfect fill out can be helped immeasurably by the addition of 2% tin. In fact, I use 2% tin added to my WW's for my standard alloy for pistol bullets (WW's+2% tin) for exactly what you are seeing - better fill out with the addition of a bit of tin.

On the other hand, realistically speaking, that small difference in weight (that you are experiencing) may not show up on the target.

I like my hollow points to be near perfect, also.