How do you get Perfect Bases?

[rsterne]

I'm pretty much a noob at casting boolits, and those I make are for airguns, so I'm using only 1% Tin to keep them as soft as possible to minimize friction.... We do, after all, have ony about 3000 psi to play with.... The velocities will always be under 1000 fps, so I don't anticipate leading to be a problem.... I have cast from several molds to date, and the larger the mold (eg. 30-35 cal) the less problems I have been having.... However, on my .25 cal bullets, particularly the 50 gr. RN .25 ACP bullet I use for my .25 cal airgun, cast from an RCBS #57902 mold, has been problematic.... I am getting a rounded corner on one side of the base, and a sharp corner on the opposite side, I assume from the side pressure of the sprue plate during shearing off the sprue.... This, of course, ruins all chance of accuracy, I'm only getting about 2" groups at 50 yards.... I want to cast some NOE 225107s, but if I can't figure out how to cure the crooked bases, I don't want to even put out the money for a mold....

I have pondered several solutions, including the following:

Cast at a higher temperature to improve the fillout in the corners.... I have already done that on my larger boolits, and that may be one of the reasons they are better, as the .25 ACP bullets, which are the worst of the ones I have done, were cast at a lower temperature (maybe 700*F)....

Use a harder alloy, say 2.5% Tin.... I'm thinking that the shear force to cut off the sprue will be higher, but that maybe the harder bullet will resist deforming better....

Cut the sprue off either earlier or later.... ie either right after the dimple forms from the contraction of the casting on cooling (like now), or wait a bit.... How long is optimum?....

Use a different method in moving the sprue plate.... I'm currently knocking it open with a large wooden dowel....

Modify the sprue plate in some way.... Any suggestions?....

I'm enjoying casting my own boolits, but if I can't get similar accuracy to what I can achieve with pellets, the extra FPE I can obtain from the heavier projectile, and the better BC, is simply not worth it.... Any comments or suggestions about how to get PERFECT bases on my bullets would be much appreciated....

Bob

[capt.hollis]

I'm pretty much a noob at casting boolits, and those I make are for airguns, so I'm using only 1% Tin to keep them as soft as possible to minimize friction.... We do, after all, have ony about 3000 psi to play with.... The velocities will always be under 1000 fps, so I don't anticipate leading to be a problem.... I have cast from several molds to date, and the larger the mold (eg. 30-35 cal) the less problems I have been having.... However, on my .25 cal bullets, particularly the 50 gr. RN .25 ACP bullet I use for my .25 cal airgun, cast from an RCBS #57902 mold, has been problematic.... I am getting a rounded corner on one side of the base, and a sharp corner on the opposite side, I assume from the side pressure of the sprue plate during shearing off the sprue.... This, of course, ruins all chance of accuracy, I'm only getting about 2" groups at 50 yards.... I want to cast some NOE 225107s, but if I can't figure out how to cure the crooked bases, I don't want to even put out the money for a mold....

I have pondered several solutions, including the following:

Cast at a higher temperature to improve the fillout in the corners.... I have already done that on my larger boolits, and that may be one of the reasons they are better, as the .25 ACP bullets, which are the worst of the ones I have done, were cast at a lower temperature (maybe 700*F)....

Use a harder alloy, say 2.5% Tin.... I'm thinking that the shear force to cut off the sprue will be higher, but that maybe the harder bullet will resist deforming better....

Cut the sprue off either earlier or later.... ie either right after the dimple forms from the contraction of the casting on cooling (like now), or wait a bit.... How long is optimum?....

Use a different method in moving the sprue plate.... I'm currently knocking it open with a large wooden dowel....

Modify the sprue plate in some way.... Any suggestions?....

I'm enjoying casting my own boolits, but if I can't get similar accuracy to what I can achieve with pellets, the extra FPE I can obtain from the heavier projectile, and the better BC, is simply not worth it.... Any comments or suggestions about how to get PERFECT bases on my bullets would be much appreciated....

Bobsaving money isn't worth it? I would not compare cast bullets with pellets . Lol

[Echd]

Try more tin before doing anything else. Tin aids fillout dramatically.

Also consider trying to run your melt a little hotter, and your mold as well. Play with the variables until you get something workable, but I imagine through either adding tin or varying mold/melt temp you'll get better results.

[Bullshop Junior]

Try raising the temp to about 800 and making a bigger puddle for you sprue

[rsterne]

Saving money is worth nothing if the accuracy isn't there, period.... I have several airguns that will do groups you can cover with a dime at 50 yards, and hold nearly MOA at 100 yards.... 4 MOA at 50 yards with cast boolits ain't gonna cut it....

I'm getting great fillout with running the melt hotter, over 800*F now, but I've been told that adding Tin when you're running that hot does no good, it just burns off.... True or not?....

Good tip on the larger puddle for the Sprue, leaving more to draw from on contraction, I'll be careful with that....

Bob

[Oreo]

Tin does not burn off. It will oxidize if you leave the melt exposed to air and the hotter the melt the worse the oxidation but covering the melt with saw dust eliminates the problem entirely.

[aussie-dave]

I was having those sort of issues with my lee 452-230-tc mold. After casting at different temps with no luck i finally opened up the sprew holes ever so slightly and now perfect fill out.

[Pakprotector]

Tin does not burn off. It will oxidize if you leave the melt exposed to air and the hotter the melt the worse the oxidation but covering the melt with saw dust eliminates the problem entirely.

Sawdust is not quite fireproof enough to tolerate casting temperatures that deliver reasonable castings for me. While it is there, there is no brown, Tin oxidizing on the surface, that is so, but run temperature up far enough to get me good boolits and it catches fire.
cheers,
Douglas

[btroj]

If it catches fire let it burn out and leave the charred remains on the surface of the melt. This gives an air barrier that helps prevent or at least slow tin loss.

[Hickory]

I have a few problem molds that will not fill out at the base.
I have found that if I use a hand ladle and pressure pour them they fill out nicely.
Not knocking bottom pour furnaces, but they have a few short comings.

[500MAG]

I have had similar issues with the 225's. Do all of the above and I found I had to slow down a little and let the lead harden a little more. The sprue will tend to tear at the boolit of the smaller caliber rather then snap it if you don't let it harden a little more.

[runfiverun]

your fillout can be helped by your mold temperature.
try the bigger sprue puddle too, this gets even more heat into the sprue plate allowing better fillout of the area you are having an issue with.
one more thing that would help if the heat doesn't work is to take a sharpening stone and run it down the corner of the mold at a 45* angle this allows air to escape and let's the alloy fill in the corners better.
i'd bet that more heat in the mold will do the trick though.
try dipping a corner of the mold in your alloy until the lead don't stick then cast with it.

[Pakprotector]

Put mold on the gas stove, resting flat on a bit of plate, turn on pot, fire up stove...wait. 16-18 lb in a Lee 20 pound pot takes just about the right amount of time to warm up as the mold itself. Ran round in circles with little molds before I tried pre-heating.
cheers,
Douglas

[grouch]

Another thing you can try if you ladle cast is pouring the lead at different heights above the mold. If you pour fairly close above the mold, you may be able to achieve a uniform and very slightly rounded corner on the bullet base, and either get a perfect base or have the flaw you describe stop short of the edge, minimizing the gas leakage from one side first that unbalances your bullet at the muzzle. If you continue to pour for a second or so after the mold fills there will be fewer core voids. Also, you immediately get better bases by opening the mold with a gloved hand instead of beating it open with a stick.
Grouch

[cbrick]

Tin does not burn off. It will oxidize if you leave the melt exposed to air and the hotter the melt the worse the oxidation but covering the melt with saw dust eliminates the problem entirely.

That's not completely accurate. True, you can reduce oxidation at the surface of the melt by covering it BUT (there's always a but isn't there) oxidation at the surface is only part of the problem with casting with Pb/Sn alloy's. The prime purpose of putting the tin in the alloy is to reduce the surface tension of the alloy as it fills out the mold, tin looses it's ability to do this past about 750 degrees. Tin also oxidizes in the stream of alloy into the mold be it from a ladle or a bottom pour pot, past 750 tin looses it's ability to do this also.

I NEVER cast a Pb/Sn alloy hotter than 715 and only that hot for small boolits and/or hollow points. What the OP needs has already been mentioned, a warmer MOLD (not pot temp) and a larger sprue puddle. If that doesn't completely solve the problem then try breaking the top edge of the mating surfaces of the blocks very slightly to allow air to escape though I've never personally neeed to do this. It's also possible that your sprue plate is too tight not allowing air to escape. 715 degrees is well past 100 degrees over liquidus temp of a Pb/Sn alloy and that's all that's needed for perfect boolits.

The sprue plate doesn't have the mass of the blocks and thus cools much quicker, keep the blocks and the sprue plate closed and full as much as possible. The larger sprue puddle adds heat to the plate and gives the boolit alloy to draw from as it shrinks inside the mold.

Rick

[HeavyMetal]

problems with base fiil out are always related to how much heat is being retained by the sprue plate, ladle pouring or not makes no difference!

RFR's suggestion of dipping a corner of the mold into the melt until lead doesn't stick to it before you pour is a good one, take it one step further and then dip the sprue plate as well then pour!

I've found the part of the sprue plate you "hit" to cut the sprue works best for this.

Now I'll give you a second tip there is no "NASCAR" casting, LOL!

Quality is always better than fast! A big ol' pile of boolits that won't group is useless and a waste of time and effort!

A very small pile that all goes in the same hole is what you want!

What this means is keep the mold hot, increasing pot temp does nothing if your mold isn't "right", waiting longer for sprue's to harden and cast at a regular rythem once everything hits the sweet spot.

Sadly this is practise and you will get better as you cast more.

[Bret4207]

You have to remember that pot temp is not the same as mould temp. A hot mould, uniformly hot that is, will give you better results than a cooler mould. Once you get the mould up to temp then it's time to play with venting, alloys, pour style, etc.

ETA- I see Cousin Rick and HM already beat me to it!

[rsterne]

I really appreciate all the answers, it seems most think I need to get the mold hotter, I'll have a go at that.... It also seems that most think I'm not getting the top corner filled out properly on one side, and the problem is not a deformation caused by the pressure of the sprue cutter.... That may be the case, as the bullets I cast later, at a higher temperature, had less problem.... I'll keep playing with it....

Bob

[montana_charlie]

You say that part of the base is sharp and part is rounded.
I don't believe that the motion of the sprue plate is 'rounding one side' as you swing it open.
If the problem was due to temperature, I don't think it would make a half & half base.
Instead, something is affecting 'how the cavity fills' on the side where the rounding is located.

Is it always the same side?
Do you have to mould tilted slightly to one side as you fill it, or as you wait for the metal to solidify?
Is your sprue plate pivot adjusted to allow the plate to swing?

CM

[rsterne]

I don't know if it's always the same side, but I have a pretty good eye for level and I always try and hold the mold level.... I just checked all my sprue plates, and they are all adjusted the same.... No wiggle, won't fall open under their own weight, but move smoothly with a lb. or two of force, not what I would judge to be too tight.... Any looser and they would have a tendency to fall open under their own weight, I would think.... I've never tried opening them with a gloved hand after a pour....

Bob

[John Boy]

I am getting a rounded corner on one side of the base, and a sharp corner on the opposite side, I assume from the side pressure of the sprue plate during shearing off the sprue....

Nope - You assumed wrong ... follow these steps and you can shave with the bases:
* The sprue plate should be loose enough so when holding the mold handles, flip it with you wrist and plate swings open
* Melt & mold temperature so the sprue puddle frosts in 5 - 8 seconds
* When you pour use a ladle and hold the spout tight in the sprue hole for 5 seconds
And with a constant rhythm, you can cast a pile of bullets with a bell curve variance of 0.5grs

[rsterne]

Good tip on the sprue plate adjustment, I'll do that.... Do you open it with a gloved hand, or hit it with a dowel?.... I understood that unless there is Antimony in the mix, no frosting occurs?.... I've never used a ladle, if you hold it tipped up for 5 seconds, won't you end up with lead running all over the place?....

Bob

[dondiego]

John Boy stated to hold the "spout tight in the sprue for 5 seconds" which prevents overflow of melt. You should end up with some overflow puddle though.

[Shiloh]

Make sure your mold is up to temp before adding your tin. I get good bullets with range scrap and only add tin as a last resort.

Shiloh

[Bret4207]

I won't say any of the advice you've been given is wrong, but I will say that each person tends to develop his own method that works best with each individual mould. Moulds often seem to have personalities of their own and what works in one may not work at all in others. I've found it's best to keep an open mind when it comes to getting a stubborn mould to cooperate. I have a couple of moulds I can think of that absolutely hate spout to sprue contact and need a drop pour to get best results. Other require contact pouring and many are very obliging no matter how you pour.

[runfiverun]

I open my molds by hand.
I just use a gloved hand and push the mold open with my thumb.
I know that the mold is hot enough to make good boolits when I can open the mold this way.
I can also judge my molds temperature this way as I get the same feeling each time I open the mold.
if it get's harder to open the mold I need to speed thing up a bit, if I feel no resistance or get a smear I need to slow down.

[rsterne]

if it get's harder to open the mold I need to speed thing up a bit, if I feel no resistance or get a smear I need to slow down.

Now THAT I can work with.... Thanks!....

Bob

[cainttype]

All good advise given. Another possible symptom occasionally arising from sprue plate adjustment is flashing from the base after you've loosened the plate...Too loose??? Maybe not.
I've seen moulds that will not fill bases properly unless the sprue plate is pretty loose. The flashing problem can sometimes be caused by movement, pouring and pulling the mould away from the pot while your alloy is still liquid. Simply using a mould guide to rest the mould and minimize movement until the sprue begins to harden can often times allow total fill-out without flashing. It will definitely allow for a looser adjustment.
A friend had this issue, coincidentally, just a few days ago. If all else seems fine but the problem persists, sometimes it's our technique.

[rsterne]

I won't have a chance to do any more casting for a few more days.... so if you have any other suggestions, keep 'em coming.... *grin*.... I'm going to get a hotplate to keep the mold hot....

Bob

[deltaenterprizes]

Perfect bases come from nose pour molds!

[cbrick]

Perfect bases come from nose pour molds!

:veryconfu

[paul h]

One thing to remember with the smaller cast bullets is its difficult to keep the heat in the mold as you are only making 50 gr bullets. Try not only a hotter melt, but a faster cadence. I've found any form of incomplete fill out comes down to a mold that isn't hot enough and that requires both a good PFD heat and a fast enough cadence to keep the heat in the mold

[Ben]

A technique that I use often on plain base molds is to remove a VERY SMALL amount of metal on the edges at the tops of the blocks. This will allow air to vent off and offer you a much improved base fill out. You can damage a mold beyond repair with this technique, so be careful and go slow if you attempt this. If you don't feel comfortable doing this but your mold needs it for proper base fill out, find an experienced caster ( who has preformed this technique several times ) that can offer help.

http://img.photobucket.com/albums/v494/haysb/Lyman%20Mold%20Tune%20UP/020.jpg

http://img.photobucket.com/albums/v494/haysb/Lyman%20Mold%20Tune%20UP/023.jpg

Maybe you can see the tops of the blocks with the edge broken slightly. Better go slow with this technique . I use a super fine cut, flat Swiss file. Once metal is removed, it cannot be put back on. Remove a little and cast, check for good base fill out, repeat if needed. Trial and error until it is right. If you over-do it ,you'll end up with fins on the base of the bullet , especially if you use very hot alloy with high tin content. Of course these fins ( if they occur ? ) will break off easily and clean up well during the sizing process.

http://img.photobucket.com/albums/v494/haysb/Lyman%20Mold%20Tune%20UP/025.jpg

[leadman]

I cast alot of 45gr 22 cal boolits and have a couple of things that may help you.
I preheat my mold in a toaster oven to at least 400 degrees, 450 is better. I dip the handle of the sprue plate in the melt for about 20 seconds. My alloy is linotype so I cast it at about 625 degrees. I fill the mold and leave a generous sprue puddle and immediately set the mold down briskly on a flat piece of steel used to cool the bottom of the mold. Two things happen when I do this (I think), the alloy is still liquid so the abrupt setting down helps "settle" the alloy, the metal plate cools the bottom of the mold which helps suck in alloy from the sprue puddle.
I also use Bullplate sprue plate lube (2 stroke oil) so I can cut the sprue while it is still pretty soft. If timed right the base is flat with no metal pulled from it. Also make sure the cutting edge of the sprue plate hole is thin and sharp. Lyman is very good about not machining the angle of the holes to the bottom and it leaves a hole with sides on it just like a drilled hole. This does not cut but tears the metal.

[gwpercle]

My method:

Clean and flux metal well, add a little tin to wheel weights and pure lead mix , about 50/50, use a double cavity mould or two dbl cavity moulds in tandem, get mould and metal to casting just below the frosty bullet stage, make sure sprue plate is not LOOSE, opens and closes easily but not swings open by itself, use a casting ladel that has a pour spout that fits the sprue hole, I have a Lyman , get ladel hot so metal flows through spout easily, fill up the ladel, press spout to sprue hole ( mould is held sideways) go rightside up with mould and ladel held in place, give the cavity a second to fill then tilt the ladel and mould apart trying to leave a sprue puddle with out getting lead in the other hole or spilling a bunch all over the bench/pot yourself. Fill the other cavity the same way. Give the sprues a count of 7 seconds to fully harden, Tape the sprue plate open , open mould and tap hinge pin if boolits don't fall out.

Thats the way I do it. Bottom pour pots don't work for me.
Gary

[melloairman]

Bob you have received a lot of good info hear . And I used the mold you have for several thousand bullets . It is a oversized mold with small cavities . The mold was larger than my RCBS 45 caliber molds and over a pound heavier than any of my other molds . But I never had a problem with base fill out after I started using 8 bhn alloy or higher . I still had to keep a fast pace but never had a problem after that . You stated that you were restricting your tin to 1 or 2 percent because of friction . I cast for air as you know and it is no different than for a PB . really . Most people including myself use a lube to fight friction . I use dry moly spray or dry slide . But a Teflon spray that dries should do well . I think if you were to dismiss the idea that all AR need pure or close to pure lead you would eliminate a lot of your problems . I have tested a lot off rifles with a lot of alloys .And I have not found one yet that will not take at least a 10 bhn alloy . You stated that leading should not be a problem at your speed . But it very well could be with out a lube . And lead shearing to the base of the bullet could be taking place as well . It is a myth that AR all need pure or close to pure lead . What I found is when I cast a bullet in the same mold and size it in the same seizer with different bhn lead . Then chrony the bullets accuracy remains the same until the fps drops ofF with the higher bhn bullet . Up untill that point the harder bullet is usable in the AR . I have included a test I did with my PB . I used the 52 grain bullet casted out of the same mold you are using . A10 bhn and then a 22 bhn bullet was used . Lubed with dry moly . Not really a large enough difference to make a accuracy issue as well . And the bullets were shot threw a LW air rifle barrel that has a .003 choke on it . GL .Marvin
http://i301.photobucket.com/albums/nn55/melloroadman/PB%2025/IMG_7292-PB251-23-13.jpg (http://s301.photobucket.com/user/melloroadman/media/PB%2025/IMG_7292-PB251-23-13.jpg.html)

[detox]

Like someone else said, "Loosen sprue plate so mould can vent better at base".

[Pakprotector]

another for the loose sprue plate...:) another for make harder boolits. tin hardens the alloy up slowly.

Now I must be slow; I run the casting as fast as I can, and I have yet to see( well...at least recognize ) overheated mold conditions. I have a 454190 single cav, and going as fast as I can, I still don't see overheat signs. That one drops at .458-, probably perfect for AG's in .457 unsized.

The RCBS 25-050-RN definitely shoots better with~4% Tin. The barrel is a BSA, and when sized to .251 I reliably get under an inch at 50 yards. have not touched the sprue plate adjuster either...:)
cheers,
Douglas

[David2011]

I don't know if it's always the same side, but I have a pretty good eye for level and I always try and hold the mold level........ I've never tried opening them with a gloved hand after a pour....

Bob

Hi Bob,

Welcome to Cast Boolits! You do have a challenging cast. After reading the whole thread quickly I don't believe anyone mentoned Bull Shop's Sprue Plate Lube or any sprue plate lube. The stuff is magic. It allows opening the sprue plate with a gloved hand while the alloy is still molten to just freezing without smearing lead on the top of the mold and sprue plate.

If you have adequate pressure on the mold cavity then level is unimportant. The pressure comes from piling up the puddle on top of the sprue plate. It will "suck in" as the alloy in the cavity shrinks. As soon as it does, open the sprue plate to minimize tearing of the base. A little more tin will not significantly harden your pellet but will increase the wetting ability of the alloy which is the key to fillout. You only need one more percent tin to get what most of us consider 'enough'.

The advice offered to this thread is some of the best I've seen in the years I've been particpating. Your requirements are much more specific than the average good caster and the advice is spot on.

David

[rsterne]

I tried some new things today.... I polished the Sprue Plate on the RCBS Mold for the .25 ACP bullets and made sure the hole was sharp, and adjusted it so that you can flick it open with your wrist.... Used the same 1% Tin I used last time, but this time I ran the temperature 750-780*F and I preheated the mold on a hotplate.... The biggest change in technique, however, was to open the sprue plate with a gloved hand instead of whacking it open with a wooden dowel.... Between the sharper, polished plate, looser fit, and more careful opening, the bases were a HUGE improvement.... Basically there was no more rounded edge on one side.... I think part of the problem was too tight an adjustment on the sprue plate pivot bolt accompanied by the violent opening.... The fillout on the mold was perfect, although I did get the occasional flash from not holding the mold closed tight enough....

After I had cast about 300 bullets, half of them hollowpoints, I sorted through and threw about 10% which had flaws back into the pot for next time.... The remaining bullets I ran through a Lee 0.250" Sizing Die which I had made from a 0.243" Die, and then I tumbled all the bullets in a rock tumbler for 10 minutes, just the bullets, no abrasive or water.... This eliminates any flash, and rounds the corner of the base very slightly, eliminating the sharp edge on the side that the sprue is cut towards.... I was VERY pleased with the results.... Here are 8 randomly selected bullets....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3790_zps6b037050.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3790_zps6b037050.jpg.html)

You can see the slightly rounded but very uniform base corner.... Here is a photo of the tumbler, and the rubber barrrel opened up with the bullets in it....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3784_zpsc5992c29.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3784_zpsc5992c29.jpg.html)

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3786_zpsf341ed57.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3786_zpsf341ed57.jpg.html)

I ended up with 130 RN Solids and 140 Hollowpoints, and they are such an improvement over the previous bullets I can't believe it....

http://i378.photobucket.com/albums/oo221/rsterne/Bullet%20Casting/IMG_3792_zps49b0e9c8.jpg (http://s378.photobucket.com/user/rsterne/media/Bullet%20Casting/IMG_3792_zps49b0e9c8.jpg.html)

Virtually all of the previous bullets had one flattened side on the base from the drag of the (too tight) sprue cutter.... and the other side dragged to a razor edge.... Not any more!.... I would really like to thank all who participated in this thread.... I learned a lot.... Fillout wasn't my problem.... the sprue plate was!....

Bob

[Pakprotector]

One more thing...:) the size of the sprue plate cutter hole. NOE mold is .1", the Lyman( and likely the RCBS ) is .150" I am attempting to acquire custom sprue plates for the Lyman 225 molds that have smaller holes and hopefully also thicker like the RCBS and NOE.

On the sprue plate and pin lube I have been using the black sticks supplied by Veral, though I have something suspiciously akin to blue 2-stroke oil supplied by Al at NOE. May have to get into that a bit and make a comparison. I also plan to loosen the NOE sprue plate a bit...it is not as loose as the RCBS and I do have a one-sided sharp edge, though the opposite is not nearly so bad as you described.
cheers,
Douglas

[45-70 Chevroner]

I had that problem with my 22 cal. 55 gr lyman mold and my solution was to weight longer than normal to cut the sprew, thus allowing the boolit to stiffin up a bit before cutting. I think "pakprotector" is correct. I also think a smaller sprew hole would be better for those small boolits. My sprew hole on the Lyman mold is almost as large as the base of the gas check boolit.

[rsterne]

I forgot to mention one other critical change to my technique.... I waited 5 seconds between seeing the sprue solidify and opening the mold.... Opening it immediately after the contraction crater formed in the sprue tended to distort the base more, tending to pull the tension side of the base corner away from the mold and bending / rounding it.... That is how I know it wasn't a mold filling problem.... It appears that having the sprue plate too tight also increases the tendency to do that.... and whacking it with a dowel can't help either.... I think on these small caliber molds the sprue hole should be smaller, I'm betting not larger than half the base diameter.... and a thicker plate couldn't hurt, it just leaves more waste in the sprue to be remelted, but gives a larger reservoir to draw from on cooling and more pressure to insure better filling.... I don't see how a 1/4" thick sprue plate could hurt....

One other thing.... When I tuned my Lyman 257420 mold, the sprue plate hole was terrible.... It didn't come to a sharp edge, the "cutting point" was about 1/32" thick.... I had to countersink it more to thin out the edge and sharpen it.... No casting results yet.... the RCBS molds had a VERY thin edge as supplied, I just had to polish the bottoms....

Bob

[rsterne]

NT

Bob

[detox]

Lead smear under sprue plate will cause uneven boolit bases. You want a "uniform base" that is sharp or very slightly rounded all the way around base.