What Did You Cast Today ???

[KnifeMaker]

Wayne, I need to trade ya out of some of those .22's to try in the BMN Maximus. 


Mike

[shamu25]

Cast a pile of 154 grain from my new Accurate 36-168J.  Had Erik hollow point it per Carl's specs.  Very accurate in my Slayer.   These are unsorted. Most drop in beautiful shape.

[triggertreat]

Very nice looking pile you have there Ray...Happy Easter!

[shamu25]

Thanks Keith.   Happy Easter to you and to all of my friends

[KnifeMaker]

Cast a pile of 154 grain from my new Accurate 36-168J.  Had Erik hollow point it per Carl's specs.  Very accurate in my Slayer.   These are unsorted. Most drop in beautiful shape.

Got t love the ranchDog designs. Very accurate.
 What is with those pin holes in the bases? Spru puddle needs to be larger.

[Kinetic45^]

Cast a pile of 154 grain from my new Accurate 36-168J.  Had Erik hollow point it per Carl's specs.  Very accurate in my Slayer.   These are unsorted. Most drop in beautiful shape.

Got t love the ranchDog designs. Very accurate.
 What is with those pin holes in the bases? Spru puddle needs to be larger.

Ahhh, Sorry, Knife, that's not a Ranchdog based design, It's my design, built on 50 years of casting and shooting in Holy Black guns, centerfire sporting/ hunting/ benchrest and of course airguns.
Long a bullet as possible (for the aerodynamic property), conventional grooves (to lighten the bullet), with narrow bands (for low bore friction) and even spacing and bore contact longer than calibur (for barrel centering/alignment), a reduced base shank and bore ride nose for accuracy and a massive HP for expansion at air rifle velocities (plus to put the CG and CP where it need to be for accuracy).
I had two prototype molds made, one from Mountain Molds then version two from Accurate Molds (the 36-168J) then worked with Al at NOE to get a 'production' batch made of the final version three (358-152-HP). Spent a little more than $1000 developing this.
I like Ranchdog and have several molds I purchased directly from him when he was producing but I did not let that influence me much in design of this bullet, beyond the fact that ALL my experience lead me to this design. It was based on the work by thousands of experimenters who built a foundation of knowledge I built my small shack on. And a lot of that I picked up as a member of the NRA.

And yes, agree that a bigger spru puddle (and perhaps a bit hotter mold/ spru plate helped by that bigger puddle) will help eliminate those pinholes by giving a larger reservoir to feed the core of the bullet as the lead cools and shrinks in the cavity.

[shamu25]

I am holding the mold up tight against the bottom nozzle on my Lee 20 # pot.  Is that what you call pressure Casting?  Lead is 750 degrees.   I find that the hollow point fills out better this way.   Mold is preheated as well as pins.

[Kinetic45^]

I am holding the mold up tight against the bottom nozzle on my Lee 20 # pot.  Is that what you call pressure Casting?  Lead is 750 degrees.   I find that the hollow point fills out better this way.   Mold is preheated as well as pins.

As with so many things, it's complicated (but simple)

Some background is that the lead cools from contact with the walls of the cavity first and lead shrinks as it cools so a void can be formed in the core of the bullet.
Pressure casting works great for nose edge and groove fill out but if you shut off the valve and there is no makeup flow the void forms from lead starvation.  If you leave the valve open longer you get a fully filled bullet but might have the lead harden under the valve needle and have to twist the mold off the spout (which sometimes causes a divot in the base of the bullet.  So some pro and cons on pressure casting.
'Regular' pouring through the spru and filling sometimes does not fully fill out HP cavities or nose lips but if the temp of pot and mold is right plus good technique it works.
There is no right or wrong and speaking personally I have tried so many things and just apply what seems appropriate for what mold n calibur and style of bullet I'm casting.  [ Small cal casting has querks but large bullet casting has totally different querks]

I do sometimes use 'timing' to start as a pressure pour then start dropping the mold down and finishing as a puddle pour as the puddle does give the base fillout reservoir and a large puddle on top of the spru plate keeps the spru hot enough (and gives me a timer, as it solidifys and crystalized it shows when to cut it... which varies in time from mold to mold and pot temp to temp but the crystalization time plus a second is always a good timer in the other variable factors {always with spru lube of syn 2cycle oil})
Takes close observation and coordinated quick hand movements and lots of practice to get it right!

All this is why casting is more art than science and difficult to master but so satisfying when you get it right.

And most of my molds have had 'prep' done before they were ever used like determining if there were enough vent lines on the mold mating faces or block top and scribing more as necessary. (And then you have to remove the displaced metal on each side of the scribed line so it does not hold the blocks apart a tiny amount or keep the spru plate from sitting fully flush)
Sometimes I take a fine file and hold it at a 45 degree angle to ONE block at the top edge where the cavity base is and make ONE light pass to take off .005 of the corner so the bullet base fiils out better and they have less rounded edges but it has to be done just right or the mold is ruined and you will get a fin where the blocks join on the bullet.  Lots of tricks that took years to learn yet take only 20 min to do on a new mold to make it work better.

[KnifeMaker]

I agree 100 percent on the method Carl states for bottom pour pressure casting. You want to drop the mold during the cast just enough at the end to form a puddle.


Breaking he surface at the bases on the face of the blocks really helps with fill out. I have not suggested it here, simply because it is a little sensitive and can be easily botched by one not accustomed to metalworking. Easy to screw up. LOL


Vent lines are very important. That is why so many different types on different manufacturers molds. The allow the trapped air to escape to help prevent hidden voids in the bullets. Keep them clear. A good hardwood fine pointed stick can remove trapped lead in them without damaging he mold itself.   I usually use bamboo kabob skewers. A sharp, fairly soft lead pencil will do as well. But dulls quickly.


Remember, the spru puddle is to both feed the cavity, especially when cooling begins, and has the added benefit of keeping the spru plate up to heat. Which helps with rounded bases.

[shamu25]

Thanks for the tips guys.   I tried the pressure pour today while lowering the mold at the last instant.   Works great and no more visible cavities.   Hurray!

[KnifeMaker]

Thanks for the tips guys.   I tried the pressure pour today while lowering the mold at the last instant.   Works great and no more visible cavities.   Hurray!

We are just happy to see you doing well. 

[Kinetic45^]

Thanks for the tips guys.   I tried the pressure pour today while lowering the mold at the last instant.   Works great and no more visible cavities.   Hurray!

We are just happy to see you doing well. 

+

[rkr]

I tested my new 257420 Arsenal mold today. It's dropping at 0.2569" while my barrel slugs at 0.2581", any suggestions how to make it drop a tad bigger bullets? The pot had unknown led mixture earlier but I've been feeding it with pure lead lately so the mix is probably close to pure. Pot PID was set at 745F.

[Bob Pratl]

What I use to do with undersize casting that I didn't want to modify the temp/mixture was to powder coat them which added .002" and than resized them + .001" to match the slug size.

[KnifeMaker]

With pure, higher heat will increase the size, but that is a lot!
Give 825 a shot.
Mike

[triggertreat]

I'll have to give this pressure pour deal a try.  I usually keep the mould down on the guide a inch or so away from the nozzle.


FWIW, I get better fill out and consistency with 800° vs. 715°.

[Kinetic45^]

OK, this is ONLY for those who have skills and feel comfortable with risk plus will not cry if they ruin a mold.

I have done this several times and been successful at increasing the size of bullet cast when I needed .0005 to .001 more (although the more you go the more chance of ruining the mold).

1. Take a cast bullet and drill a pilot hole in the base along the axis. This is hard as you don't want to damage the shape or dimensions of the bullet and although lead is soft it can grab while drilling... Might take multiple trys to get the technique down.
2. Thread in the appropriate sized screw then cut the head off so you can chuck it in a drill.
3. Using AT LEAST 1200 grit lapping compound (finer is better if you can get it), load the bullet with compound and clamp it in the blocks.  I do not use the handles, I use a vise to hold the blocks together AND make sure excess compound is not holding the blocks spaced apart (so moderation in how much compound is used, OK?)
4. On LOW SPEED spin the lap in the cavity for 15 or 20 seconds. If I'm going for more removed I use a second lap bullet and repeat the proceedure.  I've found that just reloading the used lap does not do much good, it takes a new bullet. Pull the blocks, clean and check and maybe even cast a few to see how much you removed.  Better to do it a couple of times in gradual steps than to do it too much and get an oversize mold.

Again, not for the faint of heart or someone who is not prepared to lose a mold but it can work to bring a mold to cast a better fit for a barrel.

And common sense is that an aluminum mold laps out fast while it can take 8 or 9 times/lap bullets for a cast iron mold

Some may mention Beagling a mold which works but is very slow and gives you an out of round bullet that takes a lot of accuracy robbing sizing. I don't bother with it except for making a few test casts to see if a larger bullet is the solution to an accuracy problem... try it you will see.

[K.O.]

another thing to try...

https://www.google.com/search?q=beagling+a+lee+mold&rlz=1C1AFAB_enUS481US481&oq=beagleing+a+mold&aqs=chrome.3.69i57j0l3.17054j0j7&sourceid=chrome&ie=UTF-8

[K.O.]

If it was only .0005 or so Knurling the bullet would probably have a chance at working... at .001 I would worry about stripping and leading...

From what I have read the harder the mix the larger they drop...

so Maybe cast as hard as you think will work in the barrel and then Knurl... My Buc and Urban did ok with 4-5% tin with trace antimony
and had rifling marks all around the nose just enough to be clear... this last cast with 1% tin at 740* the nose is just barely undersize on the Urban(very light marks all the way around) and under size in the Buccaneer(very light marks on one side of nose)...

so..?

http://castboolits.gunloads.com/showthread.php?192192-How-does-alloy-mix-affect-casting-size

[Wayne52]

I didn't cast anything today but I did smelt down a bunch of recovered trap pellets to make a decent pot ready for casting.  I did receive a ATI Nova Freedom (non warranty) that will be getting a taste of my cast pellets at the state land in the morning though. It's holding air perfect and all I'll need to do is sight it in when I get there.