Size of disk

[Rayc384]

I have been reading and searching through the GC threads, and I am interested in making GCs. I have two bullets that I am interested in making GCs for. One is .30 caliber and the other is a .45/70 bullet. What I am trying to figure out is for 10 thousands material such as aluminum, what size disks would I haveto punch to form the gaschecks I need. Any help would be appreciated.

[edsmith]

what is the shank size of your boolits ? what are you going to size them to ? what moulds are you using ? Ed

[Rayc384]

.30 caliber is Ranch Dog 170 grain, drawing shows .281-.285 uses 7070 gas check sized to .310

.45 bullet is Ranch Dog 350 grain, drawing shows shank .426-.430. Uses 7140 gas check, sized to .460.

I do not have these molds yet, but plan to get them soon.

[edsmith]

I don't know of you have read my diy check maker book, but in it I stress that you must measure your boolit, to get the dia. of the disk, you take the dia. of the shank, then the height of the skirt you want,times two then add to the boolit dia. that will give the disk dia.say you are doing a 30 cal. and the shank is .283 and the skirt is .060 multiply by 2 the skirt height = .120 add the shank dia. .283 = .403 disk dia. measure the boolit you are going to make the check for ! also the heigth of the skirt can vary up or down somewhat, it is not critical.

[Rayc384]

Thanks Ed, I will read your book more closely. Somehow I got confused when I was reading what you just explained. I reckon getting older doesn`t help. Since I don`t have a lathe, I am looking at the many dies for different options, I`m sure others have wandered down this path.

[WILCO]

Since I don`t have a lathe....

Get to know your "Local" machinist.

[Jim Flinchbaugh]

IF you really want to get to the nitty gritty,When bending sheet metal, to figure your needed
length, you use the formula Ed posted but, you also add 1/2-1/3 of the material thickness,
per bend
so say your using .014" aluminum, using his formula above you get .403 disk. Then add 1/2 - 1/3
of the material thickness, (.014"x.5) X 2 or (.014"x.333)x2 =.417" or .412" disk
(depending on if you used the 1/2 or 1/3) Softer metals- usually use the 1/3, harder metals use the 1/2)
Now granted for gas checks this likely isn't critical, this is just an industry standard for the formula
used to calculate the size of sheet metal needed to make a particular part. It just accounts for the
material lost in the bend(s)
(if you really want to be picky )

[Sonnypie]

What you need Ray is to decide on a check maker die for yourself.
But there is more to it than just what caliber.
I'd suggest you slug your bores first (if you haven't already) then you will have some dimensions as to where you need to look.
My 30 cal is tight, .3085". So I started with a .309" Lee sizer die. Then I polished it out to a .3105" sizer. Lee only makes .309 and .311. Why they bypassed a size is anybodies guess.

I know of two ready made check maker dies:
Pat Marlins two-step check making dies. (Although ready made does not really apply)

If you really want to get down to some brass tacks and information try here. Talk to the man, I did.
It will be a lot easier than trying to figure it out.
For example, I wanted to make 30 caliber gas checks from .016" aluminum. I got all the info I needed, and the check maker the next day via 1st class mail.
And made gas checks right out of the envelope from .016" X .500 coil aluminum.
And they filled the shank area when sized through my Lee sizing dies.
I have also made .011", and .015" gauge material, as well as .014" from flashing material.

But follow these steps...
1. Slug the bore.
2. Know the shank size of the bullet you want to cast and use, there is a standard size, so that is fairly easy. Alloys can vary and make the shank size vary a bit. (Personally I eliminate the worry and use Lyman #2 alloy from RotoMetals, no excuses.)
3. Get the tool you want to make your checks with, and the material you will be using.
(Since you don't have a lathe) (Or take Ed's instructions to a machinist to have yours made.)
I'm using the ready made versions and working on a special project.

Also a friend of mine made his own from heavy equipment pins. And that is working good as well. But he has lathes and a small mill.

Have fun whatever you decide to do.