Square Lube groove or rounded?

[mtgrs737]

Hi all, the other day I was looking through my stash of moulds and I noticed that I have two Lyman 429421 double cavity moulds. One of the moulds has the square lube groove and the other has the rounded groove. What if any difference is there? I think the square one is older but will they both shoot the same? I don't think that any other moulds I own have a squared off lube groove.

[beagle]

Old Elmer swore that the square grooves held lube better than the round grooove and that's the way he designed it.

I've noticed that if bullets with round grooves are handled, they will lose some of the lube occasionally and the square grooves won't.

In normal usage and firing, I doubt that you can tell the difference in accuracy or leading.

If I had the choice, I'd use the square groove even though the bullets are a tad harder to drop from the mould because of the square grooves hanging a bit. What the heck, I've been using several 429421s for many, many years and I haven't worn one out yet so I'd use teh square groove model./beagle

[Lloyd Smale]

Ive got both in 4 cavity molds and in just about every 44 gun in just about every load the square lube grove bullet outshoots the round. Especially at lower velocitys.

[MT Gianni]

Lloyd, does it outshoot the other by inches or 0.10ths? Gianni

[Lloyd Smale]

If i had to put a number on it id say by about 25 to 50 percent in groups size depnding on the load. To me its mostly a 2 inch 25 yard bullet and the square lube grove bullet for the most part is a 1.5 inch bullet.

[BABore]

Aside from how the groove geometry holds the lube, the lube groove's depth and shape has a great effect on how the combustion's compressive force distorts the grooves to force lube out and fill the bore well. The thickness of the base band is also an important factor. Column strength.

[JudgeBAC]

Which current mold maker has a true square bottom grease groove Keith bullet?

[AnthonyB]

IMO, the RCBS 44-250K is the closest one out there. It is my favorite 44 design. Tony

[Ghugly]

I have both square and round 429421's. As far as I can tell, they both tumble lube the same. [smilie=1:

[mtgrs737]

OK, sounds like a project in the making!

After all I aready have the hardware!

[MtGun44]

I believe that current production Lyman is back to the flat bottomed
groove on the 429421 and 358429. At least one new mold the I have
seen in orange plastic box has a flat bottom, and the pix on the Lyman
web site look like they are flat bottomed.

Can anyone absolutely verify that current production Lyman is flat
bottomed lube grooves on either or both of the Keith molds?

Bill

[GLL]

All of the Catshooter Keith style Group Buy designs by 45 2.1 are outstanding "square groove" bullets. Those moulds drop the bullets with a single tap and they generate large quanties of pretty bullets in short order ! :)

My very favorite moulds are the 4-cavity square groove Keith style from Ballisti-Cast ! :) :)
They are 2 1/2 times they cost of the LEE Group Buy moulds and worth every penny !

I own several other "square groove" Keith style from RCBS, NEI, and Lyman and enjoy all of them.

Jerry

[Lloyd Smale]

me too. IMO, the RCBS 44-250K is the closest one out there. It is my favorite 44 design. Tony

[DonH]

Re: ease of casting - IMO it is not the square groove itself which causes bullet sticking in the mould but how well the cavity is centered in the blocks (or maybe if the mould has burred edges in the cavity). I have/have cast with rifle moulds with multiple square-bottomed grooves which would allow the bullets to just about fall out. Some with round-bottom or beveled grooves hang on to bullets tenaciously.

[GLL]

I have posted this photo before but it seems appropriate here !

Jerry

http://www.fototime.com/A8441B93102C41C/standard.jpg

[L to R : Ballisti-Cast #1103, NEI #256, RCBS .44-250K, LYMAN .429-421. RCBS .44-250KT. Lyman .429-336]

[leftiye]

Salivate, slobber, drool!

[MakeMineA10mm]

Sorry to get off topic, but can someone edumicate me on the whys and wherefores of the difference between the RCBS "K" and "KT" bullets???

[GLL]

RCBS has changed the designation on some of their moulds through the years. I think the "K" was designated as "Keith" and the "KT" as Keith Type".

http://fototime.com/CA31CDAE474CB6D/standard.jpg

[L to R] RCBS 44-245KT, 44-250KT, and again 44-250K

RCBS has unfortunately changed its catalog designations around. Based on the mould boxes:

my 44-245KT is currently called 44-245-SWC #82043

my 44-250KT is currently called 44-250-SWC #82044

my 44-250-K is still 44-250-K #82080

This does not really answer your question but is a start ! :)

Jerry

[MakeMineA10mm]

Jerry, it's enough! I've never seen a good picture comparing them as-cast like that. I think I've changed my mind on which one I like better. The "K" has a HUGE lube groove and too big of a crimp groove IMO. A friend once had a mould with a crimp groove like that, and while it would accept a crimp, the bullet always remained loose, which I didn't like. (And, yes, I know that the groove can also be filled with lube, but why would you need to, with that gargantuan lube groove on that thing?!?)

The 245KT has too short of a front driving band. I would have guessed they did this to save meplat-to-crimp-groove length (possibly for short-cylinder guns), but in your pic it is pretty obvious it is the same length as the 250KT, which has a longer driving band... Perhaps it was for a short-throated chamber, like in a rifle, one where the front driving band on the 250KT would hang-up and prevent easy chambering? Another (least-likely) possibility is that they wanted to hit the number "245grs" in order to be competitive to Lyman's design?

Anyway, regardless of the reasons, I like the 250KT the best! It has pretty close to 3 equal driving bands (though the front two look very slightly shorter than the base band). It has a wide, square lube groove without being too deep. Classic SWC nose shape. And, it has a decent, without overly-large, crimp groove. I know which one I prefer now. Thanks Jerry!

BTW, just how much tin do you put in your melt to get the bullets that perfect and shiney??? :mrgreen: :drinks:

[GLL]

All but the NEI and Ballisti-Cast are linotype ! Great fillout at low temperature. :) The NEI and Ballisti-Cast are WW + about 2% tin and cast a bit on the hot side.

Just remember that the 44-250 KT is now designated the 44-250-SWC #82044 !

Jerry

[MtGun44]

In my experience, the 44-250-K is one of the best performers out
there.

Bill

[Lloyd Smale]

Jerrys right my I have the 250k the 250kt and the 250 swc and the last two are the same. Ive shot these bullets in many guns working up loads and the 250k has for the most part allways outshot the 250kt. To me the best 250 class 44 bullets have allways been the 250k and the lyman 429421 square lube grove bullet.

[9.3X62AL]

My 2-cavity Lyman #429421 is about 4 years old, came in an orange plastic box, and has square-bottomed lube groove with fairly deep crimp groove.

[Chargar]

There are no true square lube groove bullet molds. All have some angle, even it if is slight. You would have to use dynamite to get the bullets out of a true square groove mold.

I have mixed thoughts about the square vs. rounded lube groove. I think I get a little better accuracy out of the square, but it may just be psychological. If there is a difference it is slight.

[9.3X62AL]

Chargar is right about angled groove sidewalls, of course. My older #358429 is kind of an oddball, and I'm sure Mr. Keith would NOT approve--it has rounded lube groove profile, and a fairly short bottom drive band. It shoots very well, just the same. I suspect I would need to be a lot more highly-skilled with a revolver to discern much performance advantage between the two lube groove profiles.

[GLL]

I think everyone (including me) who refers to the "square" lube groove is using the term to describe "flat bottomed" vs. "rounded" lube groove profile. It is just easier than using "trapazoidal" ! :)

I am not sure one is more accurate than the other but to me the "square" groove holds lube a little better.

Jerry

[SuperMag]

Just remember that the 44-250 KT is now designated the 44-250-SWC #82044 !


Hrmmmm.....

I had a 44-250-KT that was 'defective' and I returned it to RCBS, and they sent me a current production square groove 44-250-K in its stead. I know the designations are correct, as each was stamped on the mold...

You'll note the striations on the 44-250-K... that's what you get when you fatten 'em up from .430 to .435. The bugger now weighs 262 grs of wheelweight.

http://www.salmonriverdesign.com/STUFF/twokeiths.JPG

[MakeMineA10mm]

Interesting you should point that out SuperMag, because I went to the RCBS website, and couldn't find the 250-KT (even under the right part number, jerry! :) ) any more. Looks like it may be discontinued! :(

And, another annoying thing about their "wonderful" new website, is that it doesn't say anything about cavities. Are all their moulds 2-cavity only? I know they used to make bigger ones, didn't they?

[MtGun44]

9.3x62AL,

Thanks, It certainly does look like Lyman has realized that the flat bottomed
lube groove is more popular and responded sensibly by bringing back the
older design. However, I must admit that I have about 4-5 429421 molds in
both flat bottomed and rounded lube groove style, and have had good results
with both type of molds, altho there are some molds that do better than
others. Like you didn't already know THAT. ;-)

Bill

[Bass Ackward]

Atta boy BA. You are absolutely correct.

What groove shape you really should want depends on how you want to shoot it. Some was that you can shoot it, you probably won't see a difference between the two.

If you remember, Elmer was using a 10 to 11 BHN mix at 34,000 psi which is way above the 1422 hardness theory that says top end is 18,000 psi. His biggie was that the square groove was stronger. OK. I have to believe him. It also makes the bearing area of bullets of equal weight longer. This works shifting the center of balance making it easier to stabilize and better for long range or low velocity flight.