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Thread: Sprue plates

  1. #1
    Boolit Master
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    Question Sprue plates

    I have two RCBS moulds, one with the new, thicker sprue plate, and the other without. I can grab the thicker plate with one hand, twist and cut the sprues, but with the thinner plate, no dice. I have to use my mould mallet.

    How come? I'm thinking the thinner sprue plate, being older, may not have as sharp a cutting edge. I like being able to cut the sprue without all that banging.

    The thick plate is the newer style RCBS seems to be putting on its moulds nowadays, but does anyone else make a thicker plate for RCBS two hole moulds?

  2. #2
    Boolit Master
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    There are some posts recently done which give some info and directions for sharpening sprue cutters. You'll have to do a bit of a search. The thinner plates that were originally on RCBS molds worked ok, but the thicker ones seem to...or seem to create the impression that they work better and maybe in fact they do because of the heft or mass involved. You shouldn't have to bang hard on the cutter; one medium hit or tap should (cut the sprue) do it. If the cutter is swinging free on its own weight it should come around enough to open the handles and a tap on the handle hinge ought to release the bullets. Another option is to make your own sprue cutter out of a thickness of material that you want. Its not rocket science; the existing sprue cutter that you have is used as the template to trace the outline on a small plate of new material. Then you cut out the outline and file the edges. Third is to drill the holes where they are supposed to be, but the holes over the cavities have to be smaller--or "pilot holes" that have to be enlarged slowly with a counter sink so that they are not made too big. The bottom of the sprue plate can then be polished/sharpened by putting some 400 or 600 grade emory cloth or auto body sandpaper flat on a sheet of glass and rubbing it back and forth. I did this using 3/16" aluminum plate...following the directions in an article that advocated the use of aluminum sprue plates and have been surprised and amazed by the results. Might be worth a try if you are interested. Aluminum plate is pretty cheap stuff to come by at your local recycling center (a buck will buy you a pretty big sheet) so any mistake is no big loss and you can always try it again or make a few spare cutters. The source of the original article was done by Col. Harrison in an NRA Reloading Book supplement titled "Cast Bullets". LLS

  3. #3
    Boolit Master

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    Whichever you have, funtion is improved by the application of BullPlate lube on the sprue plate.

    Shiloh
    "A society of sheep must in time beget a government of wolves."
    Bertrand de Jouvenel

    “Any government that does not trust its citizens with firearms is either a tyranny, or planning to become one.” – Joseph P. Martino

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  4. #4
    Boolit Master



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    sniper;
    I have not had any problems with my small number of RCBS moulds (they are for black powder bullet designs that call for 30/1 lead/tin - soft bullets).

    However, I have a number of Lyman moulds with their old THIN plates and they definitely are "less than desired". The solution I used was to buy thicker plates offered by a gentleman who is no longer with us. They were a REAL step up. Now, Lyman, themselves have these at a good price.

    Why don't you simply give RCBS a call and order their new thicker plates. I am sure that they will have them available (well, as sure as I can be without having tried to order them).

    I tried the E.H. Harrison aluminum plate solution offered by "Le Loup Solitaire" and it works, also.

    I MUCH prefer the heavier plates, whether aluminum or steel. The big advantage I have found (other than the real advantage in that you are not apt to bend them from striking) is they, being thicker, have a larger sprue puddle. When the bullet is turning from a liquid to a solid there is more molten lead to draw from. This minimizes "starvation holes" in the base of the bullets. You DO need to keep a rather large sprue puddle on the plate (I cover a good bit of the surface of the plate whether bottom drawing {I bottom draw all bullet sizes including the BPCR bullets} or use a dipper. The large puddle on top of the sprue plate keeps it hot so the lead stays molten long enough to "draw down" as the bullet solidifies.

    After the moulds are up to heat I then use the "hand twist" to cut the sprue (works well even with the new five cavity NOE moulds). I keep a rhythm going to maintain the same mould temperature (this helps to insure the same bullet size and weight). I consider "rhythm" when casting VERY important...

    Dale53

  5. #5
    Boolit Master Wayne S's Avatar
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    I will add that I have asked a mold maker and others that deal with Alunimum and that all suggest 6061-T6 grade for sprue plates, the one think I've found is that shipping is as much as the cost of small pieces of this plate.
    I couldn't find the article by C.R.Harris to see if he stated what grade of aluminum he used.
    I'm in the process of seeing if there is enough of the sprue hinge screw available to use 1/4" plate without having to make new hinge screws.
    I would offer that depending on what bullets you are casting you start with a smaller hole that the origional size RCBS uses, Didn't C.E.Harris suggest something along this line ?
    Also drill all your holes before cutting the new SP out of the sheet, this will offer you more control in secureing the plate while drilling and counter sinking the holes
    IHMSA # 566 "time sure flies when you're having FUN"

  6. #6
    Boolit Master
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    Wayne, I have an article by Col. E. H. Harrison titled "Aluminum Sprue Plate Rated High" and can find no direct description of the type of aluminum other than to say it had a Rockwell harness of 80. I can send you a copy of the article if you'd like.

  7. #7
    Boolit Master Wayne S's Avatar
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    Charlie,
    please do, when I talk to the Alum. supplies I'll ask about the hardness of 6061-T6
    IHMSA # 566 "time sure flies when you're having FUN"

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BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
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