Danged Pinholes

[Ian]

The bullets I cast yesterday tested out at a 10.4 BHN and will probably age harden to an 11 or maybe slightly higher...............perfect for my purposes.

NO!!!

Well, maybe, (actually it's probably pretty close) BUT:

You do not yet know that for a fact, and that is one of the most critical errors you can make during this learning process. You need to know for certain you are using the correct alloy for the job you gave it to do, and exactly why that particular alloy works for you. You can do this with several different alloy and powder combinations equally well, but the reason why they will work when properly matched to what your rifle likes will be the same.

You would be doing yourself quite a good favor to do a very detailed pressure vs group size workup of that particular alloy you're using, after it has aged out and stabilized, before you can know if it is "perfect for your purposes" or not. You might just find that adding one more percent tin to it shrinks your groups, or switching to Red Dot, or Titegroup, or 2400 with a certain charge weight might possibly outshoot any load you can come up with using Unique, or you might find that the alloy you have IS near perfect for the charges you are using now, or more perfect with .2 grains more or less, or a full grain more or less. You also might discover that 20:1 is perfect.

But right now, you are guessing it is perfect, and guessing likely isn't going to get you the groups you seek. This IS one of those areas where precision matters, and consistency of alloy matters, because each constituent of the bullet metal does certain things "for or against you" as one notable person is fond of saying. It's true, and you need to understand what 1 vs. 3% tin in a 3% antimonial lead mix does. You also need to understand what keeping .25% tin or less in a 2% antimonial mix does, and further what a 0% antimony, lead/tin binary mix does FOR you or AGAINST you when you use certain powder types, certain bullet/throat fitment methods vs. others, and various seating depths.

Since you've already had good results with someone else's bullets, hopefully you know what alloy was used to make them, saved one to measure hardness, and can come close to duplicating them. Then all you have to do is do a small but very precise load re-work in .2 grain increments with Unique to find the sweet spot with your alloy, and do another workup with same powder but slightly different seating depth adjustments or possibly a primer change or neck tension change to get even better.

But still, matching the alloy to the pressure and pressure curve, or matching the pressure curve to the alloy you choose is what is going to do the most for shrinking your groups right now. Like Rick said, you are using good tools and methods to help you learn how to cast better, more consistent bullets, and that's important, but you can only chase that rabbit down the hole so far before it becomes pointless. You will never see the slight differences a perfect bullet vs. an almost perfect bullet will make until you get the other things closer to right.

 

[Chris C]

Dang it, Ian, there ya go convolutin' my brain waves! That's an awful lot of things to consider for a newbie. But I'll copy and keep it, for sure. Thanks.

I just cast 200 bullets. After scrutinizing for boo-boos, I sorted out 21 as absolute rejects. Have to thank everyone who suggested a lower temp and faster cycle. I started out at 675 * and 15 seconds. Cast 50 and quit. The were awful. Bullets kept sticking in the mold so bad I'd lose my cycle tryin' to kick 'em out. Okay, so I started over. Went to 700* and a 30 second cycle. But I kicked the bullets out at 20 seconds and immediately closed the mold to wait for the 1 second nozzle prime before starting over. I had one of my tightest curves so far and had more bullets +or- of the longest line I've ever cast............and definitely more in the +or- .2gr lines. So my consistency is improving.

See, if you guys will just be patient with me and keep feeding me "Pablum", I'll get there.

(now I've got to go get a casting dictionary and figure out what Ian was telling me)

 

[Chris C]

Oh, and I forgot to mention, not one of the rejects was because of pinholes, so lowering the heat solved the problem....................thanks.

 

[Rick]

Chris, I'm not one to try and lay too much all at once on a new caster but you did say you've been casting for two years now. Probably time to give the grey matter a little more to chew on. Consider this, you had trouble with bullets sticking in the mold so let's consider the pot temp, mold temp and alloy in the mold temp. Bullets fall from the mold for one reason, that's because as they cool inside the cavity they shrink and no longer fit the cavity that formed them. Too hot of a pot temp and this takes longer. Too hot of mold temp and this takes longer.

You should be fine with your alloy at 700 degrees, 700 is where I do most of my casting. The rest is finding and keeping a rhythm where the bullets are well formed and release easily. Practice, practice, practice. I've never done any king of count or keep track of seconds, with practice and experience you'll quickly develop a rhythm where it's second nature and by keeping an eye things bullets will have minimum weight spread, fall from the mold well and be well filled out. As time goes on this actually gets easier.

Truth be told if had to sit there and watch a clock and do things at specific time regardless I would probably never cast again. That would bore me to tears. Casting is a bit of science and a dose of craftsmanship. Like any craftsman in any field experience is golden.
.

 

[Chris C]

Thanks for the advice, Rick. My bullets were falling out of the mold at 20 seconds when I was running the PID at 700*. I was really pretty happy with the way my curve turned out and I'm going to stick with the procedure and try it again and again to see if my rhythm consistency improves. I don't mind casting by the clock. Keeps me focused and isn't at all boring to me.

Yes, I've been casting for about two years..................but as I said, I was just pouring the lead and as long as the bullets "looked" good, all was well. But that's not really casting. If I'd been casting fishing weights that would have been acceptable. For target shooting, not so much so. I'm patient and not a quitter, so I'll just keep on keep'n on.

 

[popper]

As you found, pinholes are due to temp (& alloy). I use AL moulds and recently realized leaving them open after dropping for a 'count' gives more consistency. A device to make sure the base is perpendicular helps too.

 

[Chris C]

Aluminum here also, popper. When I dropped my bullets at 20 seconds, I immediately closed the mold, swung the sprue plate over the mold and waited until the time to prime the nozzle. Then started over. I'm pretty strict on my cadence, as one can tell. As someone once told me "it ain't what I do, but if'n it works for you.............well, it works for you".

 

[JWFilips]

Hi Chris,
Figured I'll throw my 2 cents in: I'm a relatively new caster; Cast my first bullets in Jan 2012. I had a lot of issues at first but I learned real quick from most of the great folks here (They were "over the other side of the street" at that time.) I quickly learned to cast relatively well. Once the confidence set in it was less problematical firing up the pot ( but I still can't cast with a brass mould!) I do weigh every kept bullet and sort them by .1 gr increments (Your bell curve comes in to play here) If I'm casting for my .243 win I bag up each group with a .1 gr difference ( within the Bell's first node) 30 cal & 8mm are bagged up in .3 gr increment groups ( into the 2 node) .35Rem and 357 Win are bagged up in .5 grain groups ( sometimes extending into node 3....were the lighter and heavier are used to blow out new cases) But I can guarantee you one thing...If you cast 2 days in a row Some days are better then others! some days are just plain bad even if you follow your previous day to a tee! Some day your "Bell Mean" can be as much as .5 gr from the previous day ( At least for me)
But something I do know that constancy in loading Technique trumps ( no politics intended) the quality of your cast bullets!
I have shot some of my culls to blow out full length sized cases for the first time and I ended up with one ragged hole groups at 50 yds with "Light Load" ( BTW I only shoot light loads a La BEN In all my rifles)
Hope this helps
Jim

 

[Ian]

I have shot some of my culls to blow out full length sized cases for the first time and I ended up with one ragged hole groups at 50 yds with "Light Load" ( BTW I only shoot light loads a La BEN In all my rifles)

"It only matters if it does".

 

[JWFilips]

Ah, True words spoken from one of my great mentors!

 

[Chris C]

It does help Jim, thanks.

Ian, after re-reading your last post to me on this thread, I realized I've left the impression I don't know what my alloy is. To the contrary.........I know "what" it is, just don't have a name for it. I came to casting with a box full of lead from 50 years ago when my brother and I were shooting black powder and decided we wanted to cast our own balls. We gathered anything that was supposed to be lead and put it in our big plumbers pot and mixed it all together, (wheel weights, plumbers lead, lead pipe, lead sheeting, etc., etc., etc.) not having any idea it was important to know what we were mixing! Any way, when I started casting, I started learning about what I had and what I needed to do with it. I sent a sample off and had it analyzed and it came out to be 94.1% Pb and 5.9% Sb. A learned casting friend said to mix what I have with an equal amount of pure lead and add 2% Tin. So that's what I have that casts at 10.4 BHN...........I just don't know what to call it specifically.

 

[JWFilips]

Chris,
Since COWWs are near scarce in NEPA I learned to mix those I find in a 50 /50 mix (50 percent pure lead or similar and 50 percent COWW) to this I add an additional 2 % tin
On average this gives me BHN 11.5 air cooled Perfect for shooting light rifle loads. The only bullets I fret over are my .243 because I have found that that rifle however I load it shoots dang fast! I have added some lino to this mix for that one and/or water drop or heat treat. It is a bit unfair to judge that one because it is easy shooting tight groups with that one at 50 yds ( But it is real cool and I love seeing the other shooters faces when I tell them it was using my lead cast bullets!)
Jim

 

[Ian]

Chris, you totally missed my point. You need to know what 3% Sb/2% Sn does when you touch off XX grains of XX powder behind it. I mean how the alloy reacts to the particular pressure rate you apply to it, and how the properties of that alloy work toward or against good groups within a given pressure window and pressure curve shape. Understanding, manipulating, and mastering alloy/powder-pressure relationships is most of the answer to the whole dark, rice-paper-walking, secret-squirrel-method method of loading for a high degree of repeatability at any velocity.

And still, almost no one recognizes or understands this. Particularly the ones who think they have other solutions to the problem of group dispersion. This is a graduate level topic, but you might as well start thinking about it now.

 

[Chris C]

WHEW! You're right, I've lots to learn Ian. I only graduated from Highschool, and only barely and had a year and a half of College, so I'm not quite ready for "graduate level" stuff.............but I'm here. Oh well, as long are you and others are willing to share the knowledge, I'm here to learn. Thanks for clearing that up.

 

[JWFilips]

Sure would love for Ben to chime in here! I have shot a lot of Ben's Bullets unsorted or weighed and Dipper poured! His stuff is usually within 2 /10 of a grain
He has that good old attitude "What me Worry?" from MAD magazine. He shoots one hole groups (& I have done the same with his bullets) And he doesn't even age harden them!
So there has to be more to the story
Jim

 

[Brad]

I'm like Rick, no clock or counting for me. I watch the sprue and cut/dump based on appearance and experience. I sometimes cut the sprue and see bullet bases still shiny. I let those cool a few more seconds before dumping.
A while back I decided to learn to shoot my revolved better at 100 yards. I spent a summer on the project. Rick was a huge help, never would have made progress without him. We discussed load development a bit, bullet size a bit, and revolver grip and rest a ton. We never talked bullet weight segregation. Finally got an honest 2 inch 5 shot group at 100 with a scoped revolver. I bring this up because what mattered the most was learning to shoot a revolver from a rest. Until I developed the gun handling skills required I wasn't gonna do any good.

Learn to shoot the gun and what it likes. I would run a 3-1 type alloy, 3% Sb and 1% Sn. Should be fine for what you are doing. I have run a similar alloy, heat treated, to well over 2500 fps with no trouble.

Shoot 500-1000 rounds thru that rifle with cast and it will start to come together for you.

 

[Rick]

And he doesn't even age harden them!
So there has to be more to the story
Jim

Indeed there is. With your powder puff loads and the low pressure/velocity rounds that Chris is making any gain in alloy strength from ageing would be insignificant as long as the base alloy is up to the load/pressure. With those loads most alloy's that aren't too hard to start with would work well.

As Ian mentioned as the pressure and velocity increase the more important alloy strength and bullet fit becomes. As a side note the metals industry when discussing lead alloy's they never use a hardness number but rather "strength" of the alloy for a given purpose.
.

 

[freebullet]

Really solid advice given here as per usual.

The powder & charge weight matters to me more than the tiny imperfections your trying to eliminate. Not that they aren't worth learning how to fix.

Once I have bullets that look good to the naked eye I'm more concerned with consistent & concentric brass, powder selection/weight, case mouth tension, primers, seating depth, & crimp than the imperfections it takes magnification to see.

Ever weighed jax bullets? Even match bullets have more variety than I've seen mentioned in this thread. Simply put- a lot matters a lot more.

 

[Rick]

Ever weighed jax bullets? Even match bullets have more variety than I've seen mentioned in this thread.

That is a true statement. I once weighed a box of 30 cal Sierra MatchKings, they had far more weight variation than my cast bullets.
.

 

[Chris C]

Thanks kindly to all of you. I've a lot to learn and I do appreciate all the "nudging". Some day I'll be able to cast by "feel" like you of more experience. For right now, I'm still on training wheels on a bicycle and aren't quite ready for a motorcycle. I'm sure I'll come around to what most of you have already learned.............but you learned it by trial and error and so should I.