Why are .30cal. molds from Lee & Lyman undersized?

[Maven]

All, Denver's question on Saeco molds (and my reply) prompted me to ask the above question, which E.H. Harrison himself asked (author of NRA's "Cast Bullets" based on articles appearing in the "American Rifleman" from 1957 - 1979). And yes, I know all .30cal. molds aren't undersized, and other cals. may be too, so let me be more specific. To wit, Lee, Lyman and even Saeco bore-riding designs often cast too small to give optimum results from a standard .30cal., but not .30-30Win. bbl., when cast of WW + 1% Sn, or Lyman #2 (5% Sn). E.g., my Lee C-309-180R, Lyman #311291 & its elongated cousin, #311284 and Saeco RG-4 (now #301) have foreparts that are too small (.299" - .300") and thus, don't ride the bore of my .30-06 (Mod. 70). It's not just confined to .30cal. bbls. since I have a Lyman 95gr. bore rider and RCBS 105gr. SP in .243Win. whose noses are also too small.

Does this condition exist because there"s little agreement on standard bbl. dimensions, e.g., .30cal.; because there's little agreement on what constitutes a standard alloy; because mold manufacturers (not the custom shops) were/are unable to hold close tolerances and sell molds at reasonable prices; because manufacturers (again, not the custom shops) don't set high enough standards for quality control? Have our expectations of CB performance changed so much over the last four decades that we demand better molds with more precise/better fitting CB's? Is it a combination of all of these factors? Inquiring minds want to know!

[Haywire Haywood]

I'll take a poke at it. It depends on what alloy they use as a standard when making their moulds. Lyman moulds cast .xxx using their #2 alloy, I read here somewhere that Saeco uses "Taracorp alloy" as their standard. The Dan over at MM says that WW+2%SN is terrible about producing shrunken bands and 50/50 WW Lino is even worse.

Next....
Ian

[Oldfeller]

It is to educate us on our purpose of existing -- to endlessly modify and fix our molds and equipment so that stuff actually fits.

To wit -- what does it take to get a mold that FITS your gun, land top rider style? Fits it at the worn throat end/rifling start portion?

===========================================

LEE is also "fit cowardly" -- they work to the smallest fit up they think may exist out there to keep lawsuits and complaints at bay.

They will never make a land top rider nose that fits a microgroove barrel, because somebody could stick it in a normally rifled barrel and pull a bullet upon unloading, dump a casefull of powder into their action and COMPLAIN about it.

Oldfeller

[9.3X62AL]

Dunno why the 30 caliber (or the 45 caliber rifle) molds from Lee and Lyman are undersized, but those conditiuons have paved the way for folks like NEI and Mtn. Molds to fill the gaps.

Dan's commentary about "SBS" (Shrunken Bullet Syndrome) using WW/Lino-50/50 or Taracorp are consistent with my own experience. I use a lot of Tara in rifle boolit casting, and most of my rejects are due to SBS. I messed around with casting temps while pouring this alloy, and found that cooling the alloy to ~675* F caused the SBS to practically disappear AND I gained about .001"-.0015" in diameter over castings poured at 775*-800*. This effect occurred in iron, steel, and aluminum molds--and if I intentionally ran the casting process faster (heating up the mold blocks more rapidly), SBS re-occurred and diameters shrunk back to the dimensions produced with the 800* alloy. All pouring was done from an RCBS bottom-pour furnace in drop-pour fashion.

Summed up--by cooling the Taracorp a bit while pouring, and slowing the rate down just a little, I was able to cut the reject rate significantly and boost diameters closer to manufacturers' claimed proportions.

[Char-Gar]

I have no idea why Lyman and Lee make undersize molds on the nose, but They are not the only one's. I have a couple of NEI 30 cal molds that run .297 on the nose.

However my lack of knowledge won't stop me from offering an opinion or two on the subject.

1. They just might be dumb and don't know what it takes to get accuracy from a nose riding cast bullets. I have more than once run accross folks who make and sell stuff that know less about it, than their customers.

2. They must might want to make it so it will fit ANY rifle rifle barrel and spec it for the worst possible tight barrel. Universal fit might be more important that excellent accuracy. They don't want allot of molds coming back to them.

3. Most of their customers probably don't know what it takes for a bullet to fit the barrel and don't care. We all know the myths about cast bullet inaccuracy and many folks don't expect better than mediorce accuracy.

Just a couple of guess A/K/A uninformed opinions.

[fatnhappy]

Not all lyman moulds are undersized. I have, and Kenjudo can attest because he borrowed it, a 311041 that casts .301 on the nose and .312 on the bottom band with WW alloy. The lead driving band mics .310 so the boolit actually tapers in groove diameter the right way.
That might beg the question, is my mould out of spec?

[Maven]

All, Thanks for the replies, which seem to confirm my perception of Lee, Lyman and even Saeco. Fatnhappy, Maybe manufacturer's standards change as their cherries become worn? Btw, the undersized noses on my bore riders are a perfect fit for the 7.5 Swiss (K-31) and aren't too bad in my Marlin .30-30Win. One last anomaly: My #311291 with it's .300" nose gives me almost the same level of accuracy as #314299 with a .303" nose when used in my Mod. 28/30 Finnish Nagant (Sako), assuming the same powder & charge, etc. (both are sized to .311"). However, #311291, which is clearly engraved by the [microgrooved] rifling of my Marlin .30-30, isn't the tack driver I hoped it would be. (Those honors go to Ly. #311466 and Saeco #315, neither of which is undersized.) This begs the questions, How large (or small) must a bore-riding nose be to -> optimum accuracy in "standard" .30cal. bbls.? And, does bore-riding fit (size) need to vary with rate of twist, caliber (e.g. standard .30cal. bbl v. .30-30Win. bbl.) and perhaps velocity? I await your responses!

[Buckshot]

.............Possibly in Lyman's case it may also be because they were taken to task over thier (at one time) cavity sizes. I've read in old American Rifleman mags and a couple other places of folks complaining of overly fat boolits. Possibly then all thier prints for cherries were modified from somepoint in the 1950's?

......................Buckshot

[Bret4207]

In addidtion to worn tooling (cherries cost $$$ to make) I imagine there is the "fudgit" factor. The one size fits all idea. I often wonder after looking at some of the designs out there just how much accuracy the mould maker really hoped for and how much was a W.A.G. There are a bazillion designs with long, unsupported noses that have a long lived reputation for mediocre accuracy at best. I know a few guys get good work done with them, but the majority are near hopeless. Lyman/Ideal used to make custom moulds and once a cherry was made the design was up for sale to the public. On Ebay you'll occasionally see some wild, one-off design that you can't find a number for anywhere. Add those designs with unusual diameters in with the rest of the pot and I think at some point whoever the guy in charge of figuring diameters at Ideal said, " Hey, don't make these things too fat or were going to get even more flack from the public." Another factor may be the assumtion that ALL .30 cals have .300/.308 measurments and therefore a .300/.308 boolit should be dandy.

I would think the major problem is trying to satisfy shooters who didn't want to invest in a sizer. The old manuals talk about pan lubing and cake cutters. I started out with both and there's no way you get much sizing done with a cake cutter. Guys were casting to save bucks and a sizer was/is an accessory that you don't REALLY need to pop cans at the dump. But Lyman/Ideal must have figured grossly oversize boolits would lead to problems like high prerssures and boolits stuck in throats when the guy tried to unload instead of firing. Make the cherry cut at nominal specs for the standard caliber norms and a lot of headaches go away. Just my opinion and there may well be other reasons, but I'd put money on my last paragraph.

[versifier]

Bret, I think you hit the nail on the head.

[Dutch4122]

Bret, I think you hit the nail on the head.

Ditto!