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Thread: Thoughts on Modifying a Lyman Foster Slug Mould

  1. #1
    Boolit Master

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    Thoughts on Modifying a Lyman Foster Slug Mould

    I have several of the 12 ga. Foster slug molds. I've never poured a slug with one of them for two reasons: 1 - They came to me during early winter and it's too cold to cast in the shed outback, and, 2 - I've often read that these moulds are waaaay undersize, like 0.706" diameter. But, what if...........

    What if I took the mold to a local machine shop and had them bore the bearing surface out to bore diameter, say 0.730"? Or, maybe 0.727" to allow for a good coat of tumble lube? If this situation had come up back when I was working at the shop, I'd have done it myself! Rats! But not having access to any machine tools, I'll have to employ someone to do it.

    Am I whipping a dead horse here, or do you guys think this is a viable proposition?
    "We take a thousand moments for granted thinking there will be a thousand more to come. Each day, each breath, each beat of your heart is a gift. Live with love & joy, tomorrow is not promised to anyone......"

    unknown

  2. #2
    Boolit Master
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    Try powder coating, add a 2nd coat if 1st coat is not large enough

  3. #3
    Boolit Grand Master

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    Many years ago Buckshot, who used to post here a lot, bored 4 driving bands into a Lyman Foster slug mould to bring it up to bore diameter. I think I found that thread from way back but no pictures anymore!

    So, yes it is doable but not sure what a machinist would charge. Eric at Hollow Point Molds could do it for sure:

    https://www.hollowpointmold.com/band-modifications/

    He will enlarge driving bands in existing bullet moulds so cutting three or four driving bands shouldn't be an issue at all. Not sur eof cost though.

    Since my Lyman Foster casts at 0.705" and it seems most cast from 0.686" to about 0.705" powder coating is out unless it is VERY thick powder coating!

    A couple of things you could try easily:

    - Paper patching wiht heavy paper. I have done this with some success but I think the paper patch was not leaving the slugs consistently or maybe was being damaged by opeing the crimp. Accuracy improved considerable with slugs patched to bore diameter but I got fliers. I did not spend a lot of time sorting it out though.

    - Blood Trail came up with a good idea and used heat shrink tubing on Lyman Foster slugs.

    You may want to try paper patching or heat shrink tubing before spending money on machining. However, machining works for sure.

    Longbow

    PS: I should have added that precision work is required here... though I suppose not as critical as a rifle mould but still, if you want the mould bored to bore diameter or driving bands added that are bore diameter then you will want to specify whatever your bore diameter is, say 0.729" +0.001"/-0.000". Any good machinist should be able to bore to within 0.001" and I would put the tolerance on the large side so you don't get an undersize slug. A thou or two undersize likely won't hurt but it won't help either.

    The shrinkage will depend on the alloy and LASC pur elead linear shrinkage is 1.13%. IIRC Wheelweights run about 0.5%.

    Also, I should tell you that my Lyman Foster slug mould is miserable to cast with! The slugs stick to the core pin very badly. I would polish the core pin up ot maybe add a bit more taper and polish but I don't use that mould anymore at all. i never got good accuracy from those slugs and I hate casting with the mould so... it sits on the shelf.
    Last edited by longbow; 02-07-2024 at 10:47 PM. Reason: Added PS

  4. #4
    Boolit Master

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    Quote Originally Posted by longbow View Post
    Many years ago Buckshot, who used to post here a lot, bored 4 driving bands into a Lyman Foster slug mould to bring it up to bore diameter. I think I found that thread from way back but no pictures anymore!

    So, yes it is doable but not sure what a machinist would charge. Eric at Hollow Point Molds could do it for sure:

    https://www.hollowpointmold.com/band-modifications/

    He will enlarge driving bands in existing bullet moulds so cutting three or four driving bands shouldn't be an issue at all. Not sur eof cost though.

    Since my Lyman Foster casts at 0.705" and it seems most cast from 0.686" to about 0.705" powder coating is out unless it is VERY thick powder coating!

    A couple of things you could try easily:

    - Paper patching wiht heavy paper. I have done this with some success but I think the paper patch was not leaving the slugs consistently or maybe was being damaged by opeing the crimp. Accuracy improved considerable with slugs patched to bore diameter but I got fliers. I did not spend a lot of time sorting it out though.

    - Blood Trail came up with a good idea and used heat shrink tubing on Lyman Foster slugs.

    You may want to try paper patching or heat shrink tubing before spending money on machining. However, machining works for sure.

    Longbow

    PS: I should have added that precision work is required here... though I suppose not as critical as a rifle mould but still, if you want the mould bored to bore diameter or driving bands added that are bore diameter then you will want to specify whatever your bore diameter is, say 0.729" +0.001"/-0.000". Any good machinist should be able to bore to within 0.001" and I would put the tolerance on the large side so you don't get an undersize slug. A thou or two undersize likely won't hurt but it won't help either.

    The shrinkage will depend on the alloy and LASC pur elead linear shrinkage is 1.13%. IIRC Wheelweights run about 0.5%.

    Also, I should tell you that my Lyman Foster slug mould is miserable to cast with! The slugs stick to the core pin very badly. I would polish the core pin up ot maybe add a bit more taper and polish but I don't use that mould anymore at all. i never got good accuracy from those slugs and I hate casting with the mould so... it sits on the shelf.
    longbow, I have always respected your thoughts on casting for shotguns and you've given what I consider to be as honest an opinion as can be given. I agree about powder coating, in this case anyway, I'm not going to be able to make up 25 thou' by coating the the slug. I'll give Eric a shout and see what he has to say. Thank you!
    "We take a thousand moments for granted thinking there will be a thousand more to come. Each day, each breath, each beat of your heart is a gift. Live with love & joy, tomorrow is not promised to anyone......"

    unknown

  5. #5
    Boolit Grand Master

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    Thank you for the kind words! If I can help I will try.

    If you haven't seen it this is a good read:

    https://castboolits.gunloads.com/sho...ter-style-12ga

    This describes the situation also described to me by a poster here who wished to remain anonymous. He told me that he had friends who found virutally the same as SluggerDoug re obturation of undersize soft lead slugs and that their solution was to use a copper washer directly under the slug so it had a hard flat base and would expand evenly to fill the bore.

    It makes more sense to me to cast the slug to bore diameter or slightly over so it swages back to bore diameter. It seems that the factories and Lyman didn't think it through. The common statement is that the slugs were undersize so they would pass through a choke easily... but... if they obturate to fill the hull at firing, or even obturate to fill the bore, then they have to swage down through a choke anyway so why not start them at bore diameter? That seems ot be what they are doing now and Brenneke does that with hard alloy slugs!

    I have not tried Blood Trail's heat shrink tubing idea which is a good one if the heat shrink tubing is tough enough. I recall his post on the heat shrink tubing covered slugs but I do not recall if he posted results after shooting those slugs:

    https://castboolits.gunloads.com/sho...t-part-1/page2

    Post #29

    Oooh! I just found a video of him shooting these:

    https://www.youtube.com/watch?v=U0P3e8TMW6Y

    Might be worth a try and CHEAP to try!

    Longbow

  6. #6
    Boolit Master
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    That's exactly what I did, opening up the mold. I have a lathe, and with a boring bar opened up my Lyman mold to .730. I didn't do too much experimentation with it, as I discovered the .735 RB performed so well, and stuck with that instead.

  7. #7
    Boolit Grand Master

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    There is a good point!

    Even in my smoothbore the 0.735" RB shot good groups of around 4" at 50 yards where the Lyman Foster wouldn't stay under 8" even paper patched to bore diameter... well, maybe not quite true, some groups were better but I had frequent fliers. Could have been poor patching or patches damaged opening crimps or...? So a full bore Lyman Foster may do better but there is not much to complain about a 0.735" RB from either smoothbpore or rifled gun for sure!

    Longbow

  8. #8
    Boolit Grand Master Good Cheer's Avatar
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    Erik's precision grinding machinery has been down.

  9. #9
    Boolit Buddy

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    Still have my old Lyman Foster slug mould and rifling die. I cast plenty and used a big old Lachmiller press to swag the rifling on the Foster blanks. Spray graphite made the slugs fall out of the mould and drop off the base plug. Shot them out of an original 1812 Springfield flintlock musket with good softball size groups at 50 yards. My friend had a Harpers Ferry flint musket. We both shot does one muzzloader season with them!

  10. #10
    Boolit Grand Master

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    I found it!

    Here is a pic of the Lyman Foster slug mould as modified by Buckshot:



    I guess his pictures were removed from this site because I can't find this one anywhere now and it used to show up if Googled so maybe it was somewhere else too?

    Anyway, I downloaded it years ago because I thought I might try this with my Lyman Foster mould.

    Not sure what this would do to balance point as it is adding weight to the skirt and not nose. For rifled gun it likely wouldn't matter but could for smoothbore. If it was a problem for smoothbore the core pin tip could be trimmed a bit to add weight at the nose to compensate for the additional skirt weight. That would likely put overall weight up into 500 to 600 grs.

    So, yes it can and has been done!

    Longbow

  11. #11
    Boolit Buddy
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    I had the same thought about adding driving bands, but I think Longbow has a good point about shifting the balance toward the tail. However, while you're at it, you could cut one driving band way far forward where the (largely useless) ogive of the slug is, giving it a shoulder like many Brenneke slugs. Do one more way at the back, and you should be good to go, with little change to the balance of the slug. If you go far enough forward with the front driving band, you might even make it more nose-heavy. And the rear driving band could stiffen the base a bit, which would be a good thing, by all accounts.

  12. #12
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    How about running those slugs in a Wad? I thought they were supposed to be run in a Conventional Wad anyway? Like Lee Slugs?

    That way you don't have to worry about Leading the bore which will happen with soft lead contacting the bore. (too much bearing surface)

    If you are going to do this then the mould as modded by Buckshot is the way to do a full bore slug IE: Driving Bands with Lube Grooves. Like Regular Boolits?

    I don't see the " balance of the slug" being affected in any way . What you aren't seeing is the plug in the mould. The Slug will be very Nose Heavy due to the solid Nose created by the plug, which is exactly how they designed it in the first place.

    My .02

    Randy
    Last edited by W.R.Buchanan; 02-10-2024 at 03:45 PM.
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  13. #13
    Boolit Master

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    Quote Originally Posted by FullTang View Post
    I had the same thought about adding driving bands, but I think Longbow has a good point about shifting the balance toward the tail. However, while you're at it, you could cut one driving band way far forward where the (largely useless) ogive of the slug is, giving it a shoulder like many Brenneke slugs. Do one more way at the back, and you should be good to go, with little change to the balance of the slug. If you go far enough forward with the front driving band, you might even make it more nose-heavy. And the rear driving band could stiffen the base a bit, which would be a good thing, by all accounts.
    YES! That's an excellent idea, thank you very much!
    "We take a thousand moments for granted thinking there will be a thousand more to come. Each day, each breath, each beat of your heart is a gift. Live with love & joy, tomorrow is not promised to anyone......"

    unknown

  14. #14
    Boolit Grand Master

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    Randy these slugs have a pretty thin nose and normally cast at around 0.705" or so, way undersize for typical bore diameters but too big for a wad. Some people say theirs cast at around 0.685" which may be true and if so then they should fit a wad but the spec is larger than that and mine seems to cast at what it is supposed to but stupidly small. In soft lead the skirt is so thin that they do slug up and fill out the bore but they don't seem to do so consistently and evenly.

    I thought the rifling swage you used to be able to buy for them took them up to bore diameter but apparently not from what I read. That is why SluggerDoug used helical gears to knurl his up to bore diameter.

    If made from soft lead they probably could be sized down to fit in a wad but I found that ACWW Lee slugs do not want to be sized down more thna about 0.010" or they crack and break up.

    To make that slug more nose heavy it is easiest to eithe rtrim the core pin or reset it out a bit. That would thicken up the nose some.

    By the way, when cast from soft lead these slugs have a reputation for turing into big flat washers at impact and not penetrating animals well. No personal experience with that but I can say they do flatten out in the berm! Overall, not a very good design in my opinion.

    Fulltang's comment about two driving bands and thickening the skirt is a good one. It is too thin I think.

    I haven't cast with mine in probably 20 years and likely won't again.

    Longbow

  15. #15
    Boolit Buddy
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    Seems like these could be really nice for shooting out of a rifled barrel with 2 robust driving bands and cast from bullet alloy; kinda like the "Italian" or "fire hydrant" style slugs. There are also plenty of ways to alter the core pin, too.

  16. #16
    Boolit Master
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    One of the problems I experienced with the Lyman forster, and my Rapine flying trash can mold, was the collapse of the skirt walls, and wads being driven inside the hollow cavity. Filling the base with hot glue helped somewhat. I also decreased the diameter of the plug, making the skirt walls thicker. This helped somewhat also. Still didn't shoot as well as the roundball.

  17. #17
    Boolit Grand Master

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    Yes, the Lyman slugs do have thin skirts. I had trouble with skirt collapse as well with Lyman Fosters and some others. For some I cast them from wheel weights then oven heat treated them and that solved skirt collapse. I also fill to keep wads from blowing into the cavities. I found that even hard card wads would bulge up into the cavities and distort the skirts so I put a nitro card wad or two between hard card wads and the filled slug.

    Were you shooting them out of your rifled gun or smoothbore? I ask because they are so undersize so unless they slug up I can't imagine they would shoot well from your rifled gun. Or did you machine the mould to bore diameter?

    Longbow

  18. #18
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    Yeah I got rid of mine too. I saw no advantage over the Lee 1 oz. Slugs. and the Lee mould was much easier to get good Slugs from.

    I just shot the Auto Berg the other day with a fully rifled barrel and was not impressed. It didn't like anything I fed it. I did manage to hit a Silhouette Pig at 100 yards one time but it took me 5 shots to do it.

    I have another Barrel I'm going to send to Vang Comp to get the Forcing Cone Lengthened, Ported and Threaded for Rem Chokes. That is the same thing I did to the Monkey Berg Barrel and it has worked out great.

    Auto-berg = Mossberg 500 sold by Western Auto Stores.(1st Pic) Monkey-berg = Mossberg 500 sold by Montgomery Wards. (2nd Pic)

    Randy
    Attached Thumbnails Attached Thumbnails IMG_2173.JPG   IMG_2499.jpg  
    Last edited by W.R.Buchanan; 02-14-2024 at 05:38 PM.
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  19. #19
    Boolit Grand Master

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    Randy... did you do a push thriough the bore with the slug in wad? Might be tough with rifled bore... or slug the bore and mic the slug wad combo. If that wad isn't tight between slug and rifling the slug may well skid so not pick up the spin or all the spin. I am thinking you need some squish of petals there. Maybe thicker wad petals are in order or a paper wrap between slug and wad petals.

    Or maybe you just have to find what that gun likes! You know the story!

    Longbow

  20. #20
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    I modified my wally world rifled foster slug! I slammed it into a 9pt. and recovered a coke bottle top with a hole all the way through it. The deer went to the ground instantly where he was standing. He went down so hard, so fast, he bounced back up a little and stuck his head up wondering what that noise was, so I airmailed him another one! In hindsight, I reasoned that It hadn't quite dawned on him that something was wrong.
    Got a .22 .30 .32 .357 .38 .40 .41 .44 .45 .480 or .500 S&W cylinder that needs throats honed? 9mm, 10mm/40S&W, 45 ACP pistol barrel that won't "plunk" your handloads? 480 Ruger or 475 Linebaugh cylinder that needs the "step" reamed to 6° 30min chamfer? Click here to send me a PM You can also find me on Facebook Click Here.

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