What sizing die do I need?

[DxieLandMan]

I need to get a few sizing dies. My question is: Is there a standardized diameter to get for a caliber? Need to get .45 ACP, 38/.357 and 9mm. I'm not sure what my boolit diameter is after I cast but is there an easy way to see what sizes I need? Thank you!

[DougGuy]

Most would say to slug the bores and then size .001" or .002" over bore diameter. I use .452" boolits for my .45 Colt Ruger, but my .45 ACP won't chamber anything larger than .451" it's just made on the tight side. For that pistol I found the easiest solution was to use plated boolits that are .451" and everything else size to .452"

[DxieLandMan]

Thank you DoguGuy but what does slug the bore mean?

[bedbugbilly]

On my .38s, (I cast RN, WC and SWC) I either size them to .358 or shoot them "as cast" depending on what they drop at out of the mold. On my 9mm, I only use the Lee 356-120-TC and they drop from my mold at .358 or so. For my 9mm, I size them to .357 - I also use that bullet for 38s but use it "as cast".


Your really need to use a micrometer and check your cast boolits to see what they are dropping at. And as mentioned - slug your bore (i.e. force a soft lead slug through it and measure the lands and grooves). The main reason being if they are undersize - as an example - your bore measures out at .359 and your boolits at .356 (this is an exaggeration but will give you an idea of what I'm talking about) - the cast boo lit will be too small and you'll probably lead your bore.

As already mentioned . . . a lead bullet .001 to .002 oversize should be fine. Many folks have never slugged their bore and still get along fine - just depends on what the results are when you shoot as to the leading. For my 38s and 9mm, I have a .358 (for 38) and a .357 (for 9mm) Lee push though sizing die.

As I said though, some of mine, such as the Lee TL SWC I don't even worry about sizing - they load and shoot in my seven 38 spl revolvers just fine - 4 S & W, 2 Colts and 1 Ruger New Vaquero. I have a 160 gr. Lyman WC mold that drops them a little large depending on what I have on hand and what I'm casting with - so all of those go through the .358 sizer to keep things consistent. I have a 150 gr and a 160 gr RN - the Lee 150 goes through the .358 sizer - the 160 gr, which is out of an original Winchester mold gets loaded and shot "as cast" as that is how they were intended to be shot when the mold was made close to 100 years ago.

YMMV - you don't say which bullet molds you have but you may just have to experiment and see if they load and shoot just fine "as cast" or if they need to be sized. Lee push though dies are pretty inexpensive - I got mine from Titan and they work well. Prior to sizing on them, I just TL my bullets in some Paste Wax and they push through without a problem. Afterwards, I just TL - I warm them up with a hair dryer and roll them around in a plastic bowl - add a little paste wax and then a little (very little) Alox and TL - set 'em out on wax paper and the next day they are fine to load - not sticky. Too much Alox and they will be sticky and sludge your dies up. I just load milder loads but have never had a problem with leading on any of my revolvers nor my 9mm.

Hope that helps some!?

[DougGuy]

It's a way of measuring the groove diameter of the bore, generally you force a dead soft lead ball through the barrel then measure it with a micrometer to gauge bore diameter.

[bobthenailer]

For my purposes i size boolets @0.357 for 380,9mm & 38 super, for the 38 & 357 mag @0.358 dia , for the 44mag @0.430 for most and 0.433 for two with large chamber throats, and 0.452 for the 45 acp & 454 casull, these boolet sizing dia have worked well for me over the past 40+ years in a multitude of firearms. there are always special cases that arise as with my two 44mag's.
Good Sizing Bob

[DxieLandMan]

Sorry about that. I'm shooting 9mm in a Taurus 92 and using mold TL356-124-2R which is the double cavity. For the .357/38, it is mold TL358-158-SWC. The last mold that I have is for .45 ACP and is the TL452-230-2R. I'll measure tonight and see what the diameters are.

[mikeym1a]

Since you are unfamiliar with the term 'slug the bore', let me explain. The interior of the barrel has two sizes. The bore is the original hole bored in the barrel, which determines the caliber. The rifling groves are then cut, and this is referred to as the groove diameter. When you force a lead slug through the barrel, you will get a 'mirror' image of the inside of your barrel. The raised portions of the slug will be your 'groove' diameter. The grooves you see in the slug will actually be your bore diameter. The bore is also referred to as the 'lands'. You will sometimes see mentioned as 'lands and grooves'. Once you have forced a lead slug through the barrel, you need to measure it with a precision measuring device. Many say you must use a micrometer. I have found I can use a good set of digital calipers, and get a good reading. However, as has been mentioned, after determining you 'groove' diameter', you need to size your boolits +.001-.0015 of your groove size. NOW, as far as casting boolits is concerned, I have found that my Lee pistol molds to be compatible with my .45. I have never had to size them. Perhaps I should check my 'lands and grooves' and check my boolits, but, I hit the target quite regularly. Just something to think about. Hope this helps. mikey

[DxieLandMan]

Thank you, Mikey and others. The 9mm did not cycle correctly but I think that was my fault to not putting enough powder in the round. I'm going to try the cast 45 this weekend.

[John Boy]

what does slug the bore mean?


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