What size should I spec out for my new .45 mold?

[TMenezes]

Hi guys! I have been having a great time casting my own bullets. Until now most of my casting has been done with Lee molds. Unfortunately Lee doesn't offer a 270K style mold, or a flat based LFN style mold of any style bigger than 255gr. Also I prefer casting with aluminum molds, that's why I am turning to a custom mold from AccurateMolds.com

Here's the problem, I am not sure what diameter to spec the mold out to. So let's say my Ruger 45 Colt slugs out to .451 then I was thinking I should spec it out to drop .452 slugs right? I see some of you guys speccing out custom molds .001 bigger than than your bore and others speccing for .454 and sizing them down. What are the pros and cons to these differing methods. If I spec .454 then I assume sizing becomes mandatory right?

I am not a big fan of mandantory sizing. I don't mind sizing my hunting loads, but I want my bullets to be close enough that I don't feel like I have to size the just for fun range loads used primarily for knocking down bowling pins.

Just FYI my lead is Lyman #2 mixed more or less 50/50 with scrap sheet lead rolls from the metal recyclers. I lube with a coat of LLA and load em up. I do have access to my uncle lubrisizer but haven't messed with it yet.

I am looking at the 45-270K mold or the 45-280 in a LFN looking style mold but haven't decided which one to get yet. Any suggestions on which mold I should would be cool to.

[TMenezes]

http://www.accuratemolds.com/bullet_detail.php?bullet=45-280C-D.png

http://www.accuratemolds.com/bullet_detail.php?bullet=45-270K-D.png

Sorry couldn't get my phone to paste these in my first post. These are the 2 molds I am going back and forth on. A third possibility would be the 45-270 in a tumble lube configuration. However, even though I tumble lube I have no experience casting with a tumble lube specific design so wasn't sure about going that route. I do have access to my uncles Lubrisizer but haven't messed with it yet.

http://www.accuratemolds.com/bullet_detail.php?bullet=45-270M-D.png

Thoughts? Opinions? I am interested in anything you all can teach me about this hobbie.

[MtGun44]

You need to slug the cylinder throats (front diam) and size your boolits to that
diameter, assuming it is at LEAST as big as the groove diameter of your barrel.
Some guns seem to do best with throat +.001.

Bill

[Dale53]

TMenezes;
There are several considerations here. I size to the throat diameter. In case of my Ruger .45 Colt/.45 ACP convertible, the throats are now .4525" (used pin gauges and reamed to that pre-determined size). I spec'd my mold to cast the Mihec version of the RCBS 45-270-SAA to .454" with wheelweights and size .002" (and end up with a .452" bullet). The reason I did this is that different alloys cast different sizes. The extra .002" gives me a bit of "wiggle room" so that if I cast the bullets of another alloy and it is .001" less I don't have an undersize bullet. My Star sizer sizes nose first (as does a Lee push through sizer) and it can handle a reduction of .002" without a problem. In a perfect world, as cast size would be preferable. However, there is NO perfect world and I prefer to have a bit of "wiggle room".

I have used salvage metals (wheelweights and scrap metal from dead soft to linotype) most of my shooting life with excellent results using the methods I have mentioned above. That includes high level competition.

FWIW
Dale53