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Thread: Making a Core Mold for .22 RF Jacket Bullets

  1. #1
    Boolit Master pertnear's Avatar
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    Making a Core Mold for .22 RF Jacket Bullets

    After reading some good threads in this forum I decided to make a core mold. I decided to use Lee blank blocks because they are cheap (I’ve been known to mess things up) & they are aluminum which is easy to machine. The first thing I discovered was that locating a 6 cavity blank mold is next to impossible. I was on Lee’s in-stock notification list for what seems like forever until I finally gave up. But they do have blank 2 cavity molds in stock but you must buy two! At least they both came with handles. Next I tried to decide what bit I would need to drill the cavities. I measure some of the lead wire I’ve been using & came up with .185” diameter. I have a drill press not a milling machine but I figured the right sized end-mill would probably be the best thing to use. So next problem was I’d needed to order a mill from somewhere. Finally I said the heck with it & decided to check the diameter on some of my 3/16” (.187”) drill bits. I found one a little under size & chucked it up & marked the depth on the bit with a piece of tape. I used a little math to calculate the depth I would need to pour a 55 gr core. The proper depth was hard to figure since the drill bit end leaves a pointed cavity. In true bubba style I proceeded to drill both cavities. The first thing I noticed when I opened the blocks was that the cavity edges were rough, like the bit sort of “tore” slightly along the blocks seam. A few flat strokes across a whet stone & that was fixed. One cavity turned out to be .642” deep & drops an average of 51.6 gr cores. The second cavity is .633” deep & drops a 49.0 gr cores. The maximum weight open point bullet which I can make with my RCE dies using RF jackets is 65 gr (6s ogive). I’ve found that for general figuring, the normal RF case weights is about 10gr. So the biggest core I’d need would be a little more than 55 gr. I need to go back & deepen both cavities to about .652”. The cast cores show the drill marks but they come out perfect from the squirt die. I swaged the cast cores to 40 grs because I needed to make 50 gr bullets. I bought some soft lead from a member here & I couldn't be more pleased with my final results!

    Attachment 276031 Attachment 276032
    Attachment 276033 Attachment 276034

    Here is the average weights I’ve found for .22rf hulls.

    • CCI 9.6 gr
    • Win 9.9 gr
    • Rem 10.0 gr
    • Fed 10.5 gr

    BTW: The little scale is under $10 from Amazon & is pretty handy to have around!
    Hard times create strong men, strong men create good times, good times create weak men, and weak men create hard times.

  2. #2
    Boolit Master

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    Very nice work for drill press.
    To lazy to chase arrows.
    Clodhopper

  3. #3
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    garandsrus's Avatar
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    Looks great. You might as well drill another cavity or two between the existing cavities to make a 3 or 4 cavity mold. Drill the sprue plate to match the other cavities.

  4. #4
    Boolit Master pertnear's Avatar
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    Quote Originally Posted by garandsrus View Post
    Looks great. You might as well drill another cavity or two between the existing cavities to make a 3 or 4 cavity mold. Drill the sprue plate to match the other cavities.
    Great idea!
    Hard times create strong men, strong men create good times, good times create weak men, and weak men create hard times.

  5. #5
    Boolit Master
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    I’m in the process of needing to make a core mould for .22 rimfire jacket derived bullets. I was initially going to attempt to size down 55 grain .224 cast boolits from a Lee 6 cavity mould but going from .224” to .187” seems impractical considering the .037” reduction in diameter needed to allow using the core swage die. I will try to drill the 6 cavity mould as you have described on the bottom and attach the sprue plate to allow casting/cutting of the cores.
    Decreed by our Creator: The man who has been made able to believe and understand that Jesus Christ has been sent into this world by the Father has been born of the Spirit of God. This man shall never experience spiritual death. He will live forever!

  6. #6
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    I have made core molds from Lee 2 cavity blocks (actually made the blocks to fit 2 cavity mold handles) ... I get 6 cavity molds out of a two cavity sized mold. I grind bullet point drill bits but that is not needed for cores. You can go up to 13/64 drill size ...Even a 7/32 for the core molds. Not rocket science. You can drill them a bit shallow ...mold up a few >measure> drill deeper and sneak up on the weight you desire.
    Core molds are easy peasy...I even used a some chunks of wood in a pinch.

  7. #7
    Boolit Master
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    GONRA needed a core mould for .44 AUTO MAG 183 grain FMJ bullet swaged in my trusty
    CH Swag-O-Matic press decades ago.
    (IMPORTANT NOTE! Pretty sure this project EXCEEDS Swag-O-Matic press design strength!
    Doit on a SPARE press in case frame busts! Just make a few bullets for experimenting!)
    ANYWAY - select a single cavity donor mould from yer vast Greedy Hobby Hoard.
    Setup / Center stripped blocks on block part line in a 4 jaw lathe chuck.
    Use a boring bar to bore a new cavity in the bottom. Cast iron (?) blocks machine freely.....
    Drill / tap new sprue cutter hole..... "Top & Bottom Cavities".

  8. #8
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    I decided to go 3/16 x 7/8 since the lead swages so easily.

  9. #9
    Boolit Buddy

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    Pertnear, what type of bit (HSS, cobalt?) did you use and at what RPM?

  10. #10
    Boolit Master


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    Quote Originally Posted by Rfeustel View Post
    Pertnear, what type of bit (HSS, cobalt?) did you use and at what RPM?
    Regular HSS drill bit, aluminum is soft so you can run the bit fast! Spray WD40 on the drill bit to stop the aluminum from sticking to the bit.

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Abbreviations used in Reloading

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
GC Gas Check