Boolit drop weight from mold

[HIGHRPM015]

OK. Finally got around to dropping my first boolits and a bit confused and need to be educated here please. I am using a Lee 145 SWC mold. According to the formulas for proper sealing of bore, best BHN per pressure I need to be using 12.5 BHN. My lead tested out at 12.0 - 12.2 BHN. My drops, after I got into a good rythem came out looking great. When cooled I weighed them the next day to find they average 135 grain. Now, do I worry that they came out light ? Do I change the BHN to get more weight. And if I change the BHN to get to the 145 weight mark am I screwing up the sealing of the bore? I have searched for info but sadly can't find it or just can't see it right in front of me. Learning can be fun and frustrating at the same time. What are my main concerns here so I can go forward comfortably ?? Thanks for everyone's time !!

[robg]

My Lee molds drop within a couple of grains of claimed weight ,my rcbs molds drop boolits about 10 grains heavier using the same lead mix .as long as they are consistent I don't worry.

[mdi]

For a new caster; K.I.S.S.. Pass on the formula for now. Slug the bore of your gun and if for a revolver, slug/measure the cylinder throats and size the bullets the same size as the throats (sizing the bore and throats will tell you if the throats are larger than groove diameter). For my semi-autos I started with sizing .002" over groove diameter. Use a proven, popular lube, the correct sized bullet and ignore the "formula", BHN, etc. and you'll have a good start. I cast and shot many thousands of bullets using my WW+ ??? alloy successfully, many to 44 and 357 Magnum velocities with no leading and I cast for maybe 10-12 years before I got a hardness tester. It turned out my alloy ran about 11-12 BHN...

I've been casting for maybe 22 years now and I still don't water drop my bullets and I rarely weigh them anymore. I have worked up to alloying for better performance in some guns (my 9mms and rifles like a harder alloy so I mix known alloys with linotype for a specific BHN.). I have cast for all my guns except 22 rimfire and my new 380, and using the methods above, I rarely get leading...

[Hickory]

Try not to over think this you can get a really bad belly ache.

[Beerd]

Try not to over think this you can get a really bad belly ache.

Not me, it makes my head hurt.
K.I.S.S.

..

[country gent]

Manufacturing tolerances length nose dia groove dias and actual dia can all affect weight the mould throws. Even the adjustment on the sprue plate can affect weights. Alloy also has a direct bearing on the weight also. Your hardness can be reached thru tin or antimony or both. Both are lighter and cause a change of weight. If this is a as check mould weigh them with a gas check also.
I wouldn't worry about 10 grns as long as they are consistent in weight.

One other thing is to experiment with pouring a pressure pour may force a little more into the mould making a denser bullet for the same shape / size. Same with an large sprue or icer pouring the mould. Sometimes technique make's a difference.

[bmortell]

hardness guides are just rough guidelines, it don't always work out or make sense, just got to try stuff. pretty much every block of alloy I have is about 10-12 hardness and if I need harder I oven heat treat them after casting. the mold weight is also rough and tin and antimony changes weight pretty fast. just work on optimizing diameter, lube, powder charge ect. to find accurate loads, and if its not working then go back and worry about if the alloy is right.

[Winger Ed.]

OK. find they average 135 grain.

That's pretty normal.

I've got a 90's era single cavity RCBS .45 cal. 405 grain mold.

I don't know how long I played around with various alloys trying to get something that dropped at 405.

I finally gave up when I couldn't get anything under about 415 that wasn't harder than Chinese Algebra.
Usable alloys for it in the .45/70 are closer to 420 grains.

[kmw1954]

My 1st and only mold at the moment is a Lee 356-102-R1 and with the COWW alloy that I am using it is dropping around 104.5gr pretty consistently with a variation of about +/- .5gr but those very highs and lows are small amounts and most are +/- .3gr

[gwpercle]

When a manufacturer makes a mould he can only base the weight on one alloy .
Usually they state somewhere what that alloy is . Might be Lyman #2 , clip on wheel weights , pure lead or whatever . Use that mould with makers alloy and you might get close to the listed weight.
Use some other alloy and the weight will vary from what's stamped on the mould .

My advice is to use the alloy with the bhn you want/need and don't worry about what the as cast bullets actually weigh , it's just not that important .
I use the data listed in Lyman Cast Bullet Handbook for whatever mould design I'm using...if the book says it's a 150 gr. SWC design and mine actually weigh 155 grains ... I just use the data as listed .
Always working up from lighter loads to maximum loads slowly... if I know my boolit is 5 grains heavier I will keep that fact in mind... I have never tried to push cast boolts to maximum loads .

It's normal for bullets not to weigh what's stamped on the mould ...at least when I'm casting and weighing them...but it's not a big deal either...don't worry too much about it .

More advice. If a boolit looks good , has a perfect base and well filled out..shoot it. Don't start weighing and grouping all of you pistol boolits into little groups with slight weight variances ... that will drive you to madness...load and shoot em !
Gary

[Nodakjohns]

I wish i had read this thread before i started casting lol

[HIGHRPM015]

Thank you all for the advice, duly noted !

[Wayne Smith]

To truly answer your question we need to know your caliber/bullet use and target velocity - fit is king but obduration, if needed, depends on a soft boolit. You have a relatively light boolit and if it is a .22-25 caliber you may be fine. If it is a .45 caliber??

[BC17A]

Out of my twelve Lee molds there might be six that drop within a grain or two of the advertised weight. The rest are within about 5%- 8% of advertised. I don't sweat the difference, I just work up to the best powder load and have fun. I have the 401-145-SWC on the way (if Amazon ever ships it) so it'll be interesting to see how that one does. I've been wanting a light .40/10mm plinking boolit and would be happy to see it drop a 135gn pill.

[fredj338]

It isn't your BHN but your alloy. I believe that Lee calibrates its molds with Lyman #2, so you are running more tin than needed. None of the dozens of molds I have drop the weight indicated. That is likely because I don't shoot Lyman #2.