Lyman 358311U- whats 'U' mean?

[hc18flyer]

There is an old Lyman single cavity 358311 mold with a 'U'. Before I buy it, what does the U designate? As long as it throws .358+, I'm GOLDEN!
Thanks, Tom

[GP100man]

"U" may designate "undersized" or "U" in an aphabetically numerated run, if it appers on both blocks it could have been used to keep the halves together.

Then it may mean nuttin , like what does "DW" mean on this 357446 mold ??

http://i746.photobucket.com/albums/xx110/GP100man/102_0489.jpg (http://s746.photobucket.com/user/GP100man/media/102_0489.jpg.html)

[Beagle333]

Buy it, and if it turns out undersized.... learn to powdercoat! :wink: You'll probably prefer it anyway!

[bhn22]

"DW" is a manufacturing code to identify the cherry, and the vendor of the cherry, as far as I know.

Hmmm... I have a couple of 357446s myself. The Lyman is marked "BW" & "547", and the Ideal is marked "144".

[Bent Ramrod]

Lyman used to offer "U" or "Undersized" moulds on special order for those who preferred them. At that time, a boolit cast from one of their "normal" moulds could be three thousandths over the prefix (e.g. 311) on the side of the blocks that was the nominal diameter. Consequently, the "U" moulds are likely to be closer to the nominal diameter than the normal offerings of the era. I have a 225438 U and a 311413 U both of which cast to very close to the nominal diameters.

[bhn22]

As an aside, the older Lyman bullets were often oversized. For example, I have an Ideal 358311 that drops at .360+ with a fairly soft alloy. This is likely the reasoning for the "U" molds. Also, antimony was nearly unheard of in bullet casting before the 1950s, Keith speaks of linotype in "Sixguns", only to say it's too hard for use in bullets. Hard cast bullets were usually 1:15 to 1:10 tin to lead back then. The finished diameters on bullets cast with such alloys would be a bit smaller than they would be with todays alloys.

[williamwaco]

ndersized.

See:

http://reloadingtips.com/pages/lyman-mold-reference.htm

[Char-Gar]

With use, the Lyman mould cherries got dull and were resharpened. With each sharpening they got a smidge smaller. The last time they were sharpened and used, before being discarded, Lyman marked the mould blocks produced by these last leg cherries "U" for undersized.

Folks often wonder why bullets dropped from older Lyman moulds often vary from mold to mold, and the reason may be found in the resharpening of the cherries. Get a mold cut with a new cherry and it was large. With each resharpening the bullets got smaller.

When buying Lyman moulds, you could order one of the "U" molds. Depending on the style of bullet this could be a good thing or a bad thing. It the bullet had a nose that rode the lands, it would most likely be undersized to do the job properly, but on a Loverin style mould, they would quite well, just producing a body that required little or no sizing.

I have a Lyman 311467U that is a real jewel, casting Loverin bullets that run .308 to .309 on the body.

[Scharfschuetze]

This has been a most interesting and illuminating thread. It also explains why the old sweats swore that Lyman molds were usually oversize or inconsistent and thus their recommendations to buy the Ohaus/RCBS, H&G or Saeco molds when I first started casting. I followed that advice for a couple of decades with satisfaction; but I now enjoy several newer Lyman molds that do what they're supposed to do.

[Larry Gibson]

Old Ideal and many original Lyman moulds were cut for the use of #1 alloy. That alloy was 80 parts lead, 10 parts tin, 7 parts antimony and 3 parts copper. When that alloy is used in the older 311xxx moulds, for example, they cast very close to nominal. When Lyman bought the company they continued to use the same cherry cutters and specifications. As Lyman #2 alloy (a ternary alloy of 90 parts lead, 5 parts tin, 5 parts antimony) and similar alloys became the common alloys used for casting many of the older moulds cast quite a bit oversize. Thus Lyman offered "U" marked undersized moulds for those using the newer alloys. At some point Lyman pretty much revamped the specifications so all moulds cast to nominal or slightly over with #2 alloy as the older #1 alloy was no longer used much.

For example; I've an older Lyman 311466 that casts .313+ with Lyman #2 alloy and right at .3115 with my alloy with copper in it. My 311466U casts right at .311 with #2 alloy. This gives rise to the oft heard complaint that newer Lyman moulds cast "undersized". They don't if a correct alloy such as #2 or even COWWs with 2% tin added is used. However with many batches of straight COWWs they can cast undersize just as RCBS moulds will and some others with specifications for use with better ternary alloys such as linotype.

If one wants as cast to be .002+ over nominal designated bullet diameter with plain COWW alloy then one is better off finding an older Ideal or Lyman mould or ordering a custom mould. Some small custom mould makers have designs based on plain COWW alloy (NOE ?) but a word to the wise; in case you've not noticed COWWs are becoming a thing of the past and will no longer be available in the very near future. When that happens you will be custom mixing an alloy because a good ternary alloy such as #2 alloy will then cast quite large in those moulds. You will then be asking for "U" designated moulds or buying new Lyman or RCBS..........

Larry Gibson

[Scharfschuetze]

Larry,

Speaking of the alloy's effect on diameter, you probably remember the boolits from my Hoch nose pour mould that shot/shoot so well in my 2 groove Springfield. It's diameter was specifically cut for COWW with 1 to 2% tin added and it always produced/produces a bullet that doesn't need sizing at .309 to .310."

I guess one of my projects this summer will be to come up with a batch of alloy that matches the old COWW formula for this mold.