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Old March 5, 2011, 01:55 PM   #1
Tuzo
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Cast bullet sizing question

I have started to consider casting my own after many years of reloading store-bought bullets (jacketed, hard cast, and plated). Lyman and Lee manuals have been perused and the major question is sizing cast bullets. By the way, I am leaning towards Lee casting equipment.

According to Lee, their molds are precise enough that sizing is not required most of the time. Seems that slugging a barrel will positively determine if sizing is required or not. However, store-bought bullets come in one-size-fits-all dimensions. So is sizing home-made bullets necessary? Should mold diameter be the same as the diameter of a same caliber jacketed bullet?

I would appreciate TFL members with Lee mold experience to advise on the necessity of sizing. Thanks.
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Old March 5, 2011, 02:34 PM   #2
hornetguy
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Cast bullets (called boolits, to differentiate between jacketed) generally should be sized .001 to .002 above bore diameter. You are correct, if you want to achieve best accuracy, and minimal to no leading, you should slug your bore to find out what size you need your boolits to be.
Factory swaged and cast boolits are generally sized to a middle-of-the-road size so that they will likely work ok in most guns of that caliber. It's a compromise at best. If you are going to put in the effort to cast your own, you should make them the size YOU need.
I have just now started using my first TL mold, for the 45-70, so I can't give you firsthand knowledge of whether ALL TL molds will allow you to shoot as cast, but I've heard quite a few shooters say that is the case. Just remember, if you are casting gas-checked boolits, they will have to be run through a sizer to set the check on the base. I have, in the past, used a lubrisizer and pushed just the base and check down into the sizer to "seat" the check, without sizing the boolit. Don't be afraid to experiment.
I have shot several of my boolits, in different firearms without sizing, depending on my slugged bore dimensions, and my boolit dimensions. Much of this is a "try it and see" kind of thing... there really aren't many hard, fast rules. You can probably get by shooting a boolit .003 or maybe even .004 over bore size with no problems, as long as you let signs of excessive pressure and accuracy guide you.
If you are shooting boolits from a revolver, the critical dimension is not so much bore size, as it is the diameter of the mouth of each chamber in the cylinder. The boolit has to be that diameter, or .001 over, or you will usually get very iffy accuracy, and some pretty bad leading of the bore. My wife's 38 snub Taurus has chamber mouths of .360 diameter, and I was getting some pretty bad leading in the first 3/4" of rifling when I used "store-bought" cast boolits. I'm now casting a SWC that is dropping right at .360, so I'm pan lubing them with no sizing at all. I'll do a report as soon as I can get out to the range.
Good luck with your venture into casting... it's an addictive, sometimes frustrating, most of the time fun, kind of addition to reloading.
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Old March 5, 2011, 02:46 PM   #3
Nomadicone
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hornetguy pretty much covered it. In my experience sized bullets shoot better than those shot without sizing. You can certainly start out without sizing and see if you are satisfied. I have used Lee molds and others and just tumble lubed, loaded and shot but over the years I always go back to sizing as I can see the extra effort pays off. You may get a mold that drops the bullets perfectly round and of the right size and if so I'd load em and shoot em.
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Old March 5, 2011, 06:21 PM   #4
stang68
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I use a Lee TL358-SWC mold and it was dropping boolits .359-360 and out of round. I got the Lee sizer (358) and honed it out to .359 which my Marlin 1894C with microgroove rifling likes for accuracy so for me the sizer was needed.
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Old March 5, 2011, 08:00 PM   #5
Adamantium
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I started out in the "no need to size" camp but quickly moved away from it. Now I tumble lube, size then tumble lube and am much more happy with the results. Using my molds (Lee 6 cavity) and used wheel weights I have seen them drop anything from exactly on to .006 too large. Because I am not using an exact alloy each batch is slightly different but usually somewhere in the middle. Now that I push every bullet through a sizer die it no longer matters. It also saves me from throwing overly large bullets back into the lead bucket because they bulge the brass when I load them.
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Old March 5, 2011, 08:42 PM   #6
Edward429451
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Quote:
drop anything from exactly on to .006 too large.
WW alloys wont vary that much IME. I think what you are experiancing is from lack of heat control. If you cast with temps all over the place you will get results like you describe. The melt gets hotter as it gets closer to the bottom, chunking sprues and rejects back into the pot and continuing to cast without letting the temps even out again will do it also.

You need a casting thermometer, or a K type thermocouple and a multi-meter to keep the melt +-10 deg and your boolits will be closer to Match grade.
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Old March 5, 2011, 08:58 PM   #7
GP100man
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I started out TLing but qwikly moved to a sizer & conventional grooved bullets (they don`t like boolits over here) for optimum performace from full bore loads !

I TL some of my plinkin bullets & have no problems in my revolvers ,fit or foulin.

Some bullets may require sizin for the auto loaders that headspace on the mouth , a big bullet may affect feeding & going into full battery!

Revolvers headspace on the rim & if it`ll chamber your good !

Sizing I feel is needed for those of us that load our SD/HD ammo, this is what I do . I size the bullet .358 (for either 38 or 357mag) & after loaded each round is tested in each chamber of each revolver it may be used in for function.

That`s my take on sizing others may wish not to & shoot thousands of rounds with out all the trouble of sizing , but I do !

Oh yeah , burnin alox gives my sinuses a fit , so useing a lube sizer offers different options on the lube ya can use !

Hunting , plinkin gets 359 bullets , hunting rounds get checked in each chamber for function.
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Old March 5, 2011, 10:50 PM   #8
hk33ka1
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When I want to seat a Gas Check without sizing I use a larger Lee push through sizing die. Example is my .312 Lee Boolits for .303/7.62x39 etc drop at 312/313" so I put a check on them and run them through a Lee .314 sizer die to crimp the check without touching the boolit. You could also just buy a sizer the size you want and sometimes I do, but if it is a non standard size you're looking at about $40 to your door for a custom from Lee vs a $16 production size.

I also size 1-3 .000" over groove diameter. (.309-.311 for a .308 Win , .358-360 for a .357 mag etc) Slugging your own bore is the best way to know what this size actually is for your barrel, but some common guns have come to a unanimous internet concensus.
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Old March 5, 2011, 11:25 PM   #9
Adamantium
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Quote:
WW alloys wont vary that much IME. I think what you are experiancing is from lack of heat control. If you cast with temps all over the place you will get results like you describe. The melt gets hotter as it gets closer to the bottom, chunking sprues and rejects back into the pot and continuing to cast without letting the temps even out again will do it also.

You need a casting thermometer, or a K type thermocouple and a multi-meter to keep the melt +-10 deg and your boolits will be closer to Match grade.
Bullets within a batch are consistent, variances from batch to batch is what I am describing. I don't put my sprue and rejects back into the pot until it runs empty and needs to be refilled so that doesn't apply. I'll adjust the temp gauge on my pot to keep my slug's dwell time in my mold down to a minimum but thats about it.

When shooting from a rest at 25 yards my bullet holes touch each other so maybe I'm not seeing the logic in changing what I do.

Last edited by Adamantium; March 5, 2011 at 11:43 PM.
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