what does "u" designate on a Lyman mold

[Brother_Love]

thanks, malcolm

[beagle]

A prefix "U" indicates a mould that was cut with an undersize cherry. I have several so marked in my moulds and the .45 ACP casts at .452" and the .30 casts at .310 so they're really not that undersize./beagle

[lurch]

I thought the "u" designated an undersize mold... No?

[Brother_Love]

I was afraid it was for undersize. I just purchased the mold and did not know of the "u" designation until I received it. I will cast a couple in a little while and mic them. If it iundersized I will list it in classifieds and maybe someone else needs it.
Thanks, malcolm

[.30/30 Guy]

+1 for lurch

I have a Lyman 358495U that casts at 0.356.

[Brother_Love]

Just cast about 15 of them and they "mic" at .311[smilie=w: (would have dobne more but it is 90+ outside at 10 am). I am happy plus this is a magic mold. I heated on top of the pot, first bullet was a keeper and they drop as I open the mold:bigsmyl2:. I wish all of them would work like that.
Malcolm [smilie=s:

[Crusty Deary Ol'Coot]

Sorry,

Don't know what the "U" stands for, but if you see an "R" stamped into a Lyman mold, it is a "reject" mold for whatever reason.

I haven't checked it out for awhile, but they used to have a list coming out for grab bag mold offerings, which were stamped with the "R".

These might be a mold which was cut slightly wrong, a discontinued style, one which was rusted, or????.

I have had a few, all of which cast fine.

One a .44 mold cast waaaaaaaaay heavy for that style/number, but the boolits shot like crazy in my SBH Hunter.

When the list came out, it was first come, first served.

AS I recall, an "R" mold did not have the normal Lyman warrenty.

Keep em coming!

Crusty Deary Ol'Coot

[MT Gianni]

The U came about in the 50's and early 60's when lube-sizers were not always true and sizing in some cases hurt accuracy. The molds labeled 311xxx were actually undersized to cast .309 and minimize sizing for shooting as cast. Most are not under bore diameter.

[JeffinNZ]

From the feedback of late it appears all Lyman's new moulds should have 'U' stamped on them.

[Catshooter]

Well Jeff I've bought eight Lymans from Midway over the course of the last seven or eight months and none have other than perfect. Don't know what to say.


Cat

[captaint]

So, now they're all marked U and R.......right??? Hehe Mike

[9.3X62AL]

Buckshot "got" me again. He told me the "U" stamping meant that the mould was intended for underwater use only. He didn't specify dipper or bottom-pour casting. Maybe the CASTINGS are for underwater use only--like fishing weights. Maybe he'll come out tonight and clear this all up.

[Bent Ramrod]

A lot of the Lyman moulds of that time were significantly oversized. I have a nominal 311291 that is .314 or so on the diameter and a 316475 that is .319. Castings from moulds like these tended to stress the Ideal #45 Lubrisizer unduly when they were sized down to the diameters recommended by the gun writers of the day. It may be that Lyman hit on the marketing ploy of offering the "U" designation to get a few more moulds out of cherries that had started out well beyond maximum dimension and were now sharpened down to an irreducible minimum. The two or three "U" moulds I have are actually pretty close to the nominal mould diameter.

[Char-Gar]

Lyman sharpened their cherries several times over their useful lives. Each time, they go a hair smaller. When the cherry got down to their minimum specs, they made one more run of molds and makred them U for undersize. After than run, the cherry was distroyed and a new one ground.

[Green Frog]

OK, so what if the letters after the numbers are "C" or "D" instead of "U?" I have a 515139 C and a 515139 D, the former of which I use for my Maynard 50 and the latter of which is just waiting as a backup. The only rumor of explanation I ever got was that the letters were to denote different cherries by different makers(?)

Froggie

[Ben]

From the feedback of late it appears all Lyman's new moulds should have 'U' stamped on them.


That's the best one that I've heard lately.
Based on my attempts to obtain a decent copy of the Lyman 311284, I'd have to say that I'm in full agreement with you Jeff !

[crazy mark]

It means "unsafe" and you should send it to me. It will cause you to cast dangerous boolits.

[Crusty Deary Ol'Coot]

Mark, you are indeed "Crazy"!!!!!!:kidding:

Considering you live in Oragone and/or Wershington, both soon to be infected with Califunnyia - ittesss. :hijack:

Therefore, All the molds are being collected over here is Ideeeeeeeeeeeeeho where they will be loved and fed and groomed and in general well taken care of.:smile:

Those wishing to protect your valuable and much loved booooooolet molds, need only send me a "PM" requesting my mailing and or UPS address. A loving home awaits!

:lovebooli Keep em coming! :cbpour:

Crusty Deary Ol'Coot ;) [smilie=1:

[Changeling]

Unreliable.

[JIMinPHX]

would have dobne more but it is 90+ outside at 10 am

Sweater weather out by you then...

About 110 here & the AC quit on me the other day.

[Bent Ramrod]

I've heard the later letters (other than "S" and "U") are codes for the cherries, which Lyman now buys from a toolmaker. No more in-house tooling production,apparently.

[Larry Gibson]

My older Lyman 311466 drops the bullets at .314 which I find to be some what large although they do shoot quite well in my .30 cals when size down to .311. In January I picked up a 4 cavity 311466U in excellent condition while on a trip for a very good price. I just recently got atound to casting some bullets in it. They drop right at .3108 and are very consistant in weight and dimensions cavity to cavity. Hornady GCs fit perfectly on the shank and the slide into a .311 sizer for lubing quite effortlessly. I've 550 of them cast, GC'd and lubed and will try them in my Palma 14" twist barrel from 1900 up to 2600 fps. In this case I'm not sure that the "U" means "undersized" as they are casting out pretty much at .311 as a "311xxx" mould should.

Larry Gibson

[J..]

Lyman has/had several codes that were stamped on moulds.

The "U" does indeed stand for 'undersize'. Additionally, the following codes were also used:

"O" - Oversized. These are sometimes encountered but not nearly as often as the U.
"S" - Short. The mould casts a weight lighter than the normal nominal weight for that mould.
"L" - Long. The mould casts a weight heavier than the normal nominal weight for that mould.
"EX L" or "XL" and "EX S" or "XS" were also used to denote 'extra long' or 'extra short'.

The S and L were usually used on bullets that featured many grooves and by adding/deleting grooves the weight was changed (the Herrick-style bullets are good examples of this).

These notations were pretty much obsolete in the late 1970's when Lyman did some major housecleaning in their mould production. By then the "B" and "C" (Special List) were discontinued and all a shooter could get was the "A" list, or normal production items.

In more modern times, individual cherries are given two-letter suffixes. For example, if you buy a #429421 it may be stamped "429421 AW" or "429421 BX". Those are strictly for keeping track of usage and tracking any problems with a specific cherry.

And, of course, each half of the mould block is stamped with an assembly number to keep the two halves from getting lost in production.

There may be a couple other codes that were stamped on moulds but I haven't come across any others in my research.

[Crusty Deary Ol'Coot]

"J" Thanks for all the info.

But, don't forget the "R" which stands for "reject".

I have one here on the desk in front of me, and as I stated in an earlier post, it was a marking put on substandard or discontinued molds sold in Lyman's grab bag offerings.

A mold stamped "R" was not under their normal warrenty.

Each of the "R" molds I have had, cast fine and one, an waaaaay over wt mold. for .44 shot extreemly well!

Keep em coming!

Crusty Deary Ol'Coot

[Changeling]

Urin Now, don't call us!

[adrians]

i have a lyman 457124U havn't cast any yet ,it waits to be seen if final dia is as advertised.

[shotman]

ok what does B mean?

[Bret4207]

The "S" was also used for "Special". I have Lyman literature somewhere that notes that. The Problem is, what does "Special" mean? Light, heavy, undersized, oversized, hollow based, flat based, tapered, extra grooves or fewer than normal. I've seen all mentioned as coming in under "Special" from back in the day when Lyman would cut custom cherries.

And then there's the 360271S which always seemed to be an "S" mould.