As cast diameter for Lyman foster slugs for 20 and 12 gauge?

[catboat]

Seeking information please.

What is the “as cast” outside diameter of the slugs from Lyman’s Foster slug in 12 and 20 gauge?

Not referring to the newer “air gun pellet” shape slugs. I am interested in the “old fashioned” parallel-sided, round-nose, hollow-base 12 and 20 gauge design.

Thanks in advance.

[longbow]

My Lyman 12 ga. Foster casts at 0.705" so way too big for shotcup and way too small to shoot naked!

If cast of soft lead they do slug up to bore size but slugs recovered from deep soft snow tell me that they do not bump up evenly or they are so small they cock on their way into the bore as they bump up because the noses and skirts were very uneven... and no it wasn't from impact. Poor accuracy was the result.

I think these slugs cast so small because Lyman (Ideal?) used to sell a swaging tool to put rifling on the slugs. My guess is that if the rifling impression was 0.008" to 0.010" deep then the lead displaced about that much beyond as cast size bringing the slugs quite close to bore diameter.

I never got mine to shoot well regardless of load recipe and following Lyman instructions to the letter. Also, one of our former site members advised me that if I put a copper washer under the slug it would help bump the slug up evenly and consistently... didn't improve accuracy for me. Horrible slug to cast and horrible accuracy at 8" to 12" groups at 50 yards.

Paper patching with thick paper helped but I still got fliers.

More than you asked for.

I would not advise buying a Lyman Foster slug mould if you are expecting to get an accurate slug. If you have another use for them not shotgun related you may be okay.

YMMV

Longbow

[catboat]

Good info, thanks. I was actually thinking if paper patching would help, but I just didn’t know if they were .005-.008” under bore, or more. Sound like “ much more.”

I was also wondering of the idea of a nylon ball under the hollow base would bump it up, like the Federal Tru-ball slug. Something like a 1/2”, 9/16, 5/8”, diameter ball would work.

Also was wondering if the diameter of the hollow base pin could be turned down (reduce diameter) which would thicken/ strengthen the sides/walls of the slug to resist slumping on acceleration- but the outside diameter of the slug needs to be closer to bore diameter ( of smoothbore).

I just wonder a lot I guess. Thanks for the info.

[Cowboy_Dan]

You didn't ask, but my 16 gauge Foster from Lyman mikes at .653" with a .487" hollow cavity from pure lead. That's .012" undersize, but it fits reasonably well in a 12 gauge shotcup. Until there are enough orders for Mihec's 16 gauge diablo, I may have to stick with the .662" (casts .665" in COWW) RB in my 16.

[longbow]

I think it was Buckshot who machined driving bands into a Lyman Foster slug mould for a fellow some years ago. It looked good and apparently worked better but I can't recall if he was using smoothbore or rifled gun.

If I was not able to make moulds and wanted a bore size HB slug I'd be looking at the Mihec full bore Lyman sabot slug clone or going to Accurate for the mould and a machine shop or gunsmith for the HB pin... or Brooks for a custom mould.

I still like the wad slugs as they are easier to load and I am lazy!

You might try paper patching but I'd recommend filling the cavity with silicone caulk or hot melt glue before paper patching. That is something I did not do in the past but likely should have.

Longbow

[CastingFool]

My 12 ga foster slugs mike at .691-.694

[longbow]

I've seen at least one other posting of Lyman Foster casting same size as mine at 0.705" but I also saw one post where a fellow said his mic'd a 0.685" or thereabouts but small enough to fit in a shotcup... which is real small! If Lyman Foster slug moulds vary that much one has to wonder.