OK, I'm confused. Help straighten me out.

[BJK]

I've been looking at molds for .300BLK subsonic. I found an MP mold that casts .311D bullets. Clearly these will need to be sized after coating them. I think my understanding of that is correct. Yes?

I found a LEE mold that casts .309D bullets. If the bullet needs to be larger than the bore how can these be sized? What am I missing?

TIA

[Czech_too]

It's been my experience that most moulds, regardless of maker, will drop a larger than designated boolit. This difference may be as little as .001 to as much as .003
Factors to consider here are the temp. of the melt(lead) and the temp. of the mould. The higher the temp. the more expansion, material wise, of the mould. The same can be said of the melt(lead).

[Rcmaveric]

While most mold makers mark their molds by the diameter of the bullet they drops. Lee seams to mark theirs by the bore they are designed for.

Regardless of maker. I always verify actual bullet diameter. Alot of things affect bullet diameter like alloy and casting Temps. Its not uncommon for diameter to be different than whats labeled.

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[ABJ]

The main three corporate mold makers use a specific alloy to determine the as cast size.(RCBS,Lyman and Lee.) Magma uses 92-2-6. Lyman uses Lyman #2, not sure what lee or RCBS use.
I think you would be better served using Accurate Molds because you spec the mold to your alloy. This will take the surprise factor out.

My experiences with Lee rifle boolits, and all Lyman and RCBS throw a little small with my alloy which is 94-2-4. Conversely Lee handgun molds seem to throw a little large, go figure.
Tony

[GhostHawk]

There is also one other option. To "bump" them up then size them.

Even giving one a tap with a rubber mallet to seat a gas check will bump them up "some"
More so with softer alloys.

They can also be increased in size in the bore. Called "Obteration" This was used in many black powder guns.

[Rcmaveric]

The main three corporate mold makers use a specific alloy to determine the as cast size.(RCBS,Lyman and Lee.) Magma uses 92-2-6. Lyman uses Lyman #2, not sure what lee or RCBS use.
I think you would be better served using Accurate Molds because you spec the mold to your alloy. This will take the surprise factor out.

My experiences with Lee rifle boolits, and all Lyman and RCBS throw a little small with my alloy which is 94-2-4. Conversely Lee handgun molds seem to throw a little large, go figure.
Tony

I forgot about that. Alot of the mold makers have on their websites what alloy they use or what alloy the mold is calibrated for.

Some of the makers will allow you to specify your alloy for the mold.

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[BJK]

Thanks gents!

FWIW, at this time I'm planning on subsonic loads and COWW for lead, Hi-Tek coated bullets. I may eventually want to go supersonic with cast but I'll cross that bridge when I get there.

edit: So I just placed a BO for the LEE mold. I can't cast anything until winter relaxes it's grip and I should have by the time that happens. Now I need to find a push through sizer. Like I did with the 9mm sizers should I order a range? It's for .300BLK (at this time, but maybe other .308 firearms in the future) so I assume I want .308-.311 would that be correct? Any changes you'd make to that? What I see available are .308, .309, and then it jumps to .311.

[Rcmaveric]

Cast bullet sizing is a debated subject. My personal opinion is to go with the largest that will chamber reliably. The more support the bullet has the better.

Only 30 cal I own is a 30-30. Its throat diameter is .310 and that is what I size to. However, 9mm calibers i have several different cartridges and multiple fire arms of each. They all have .358 throat so I only needed one diameter sizer.

So just buy the mold and then buy additional sizes as and when needed. I always look for a bullet designed for the intended cartridge.

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[BJK]

I'm just trying to make sure I have what I need. I don't trust todays changing political winds.

This is the LEE mold I B/Oed (see link below). It's definitely for .300BLK. So is the MP mold that I have my eye on and that's an 8 cavity mold designed for production.

https://www.midwayusa.com/product/1010217751?pid=938614

[Rcmaveric]

I would roll with the Lee mold. Measure the the throat diameter of the gun and order that sizer.

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[Burnt Fingers]

A lot of people have had poor results with that Lee design.

I have the MP and it shoots much better than the Lee in my gun. Also the boolits out of my Lee are undersized. They barely make .309

[Conditor22]

I really like this boolit for 300 B0 subsonic https://noebulletmolds.com/site/shop...ty-gc-whisper/

I shoot it without adding a GC and it's a tack driver over 700X, 2400, H110 and 1680

My guns like 300 BO boolits sized to .309.

I started with lee push through sizing dies then switched to NOE sizing bushings

With NOE, once you buy the bushing body Push Through Size Die Body https://noebulletmolds.com/site/prod...size-die-body/

The 30Cal .309 Body Bushing (B309) cost $9.75 per size change https://noebulletmolds.com/site/shop...-bushing-b309/

and you only need 1 30Cal Push Rod (30PR) $7.50 for all 30 cal boolits (lee & now pushrods are interchangeable.

The NOE system takes much less room to store.


To be really sure where to start in finding the size best for your barrel doing a chamber cast (pound cast or pour cast) or pound casting the barrel is the way to go.

now you get into finding the best diameter boolit for the alloy/hardness of boolit for how hard you want to push the boolit ie finding what your gun likes best.

[notenoughguns]

I'm just trying to make sure I have what I need. I don't trust todays changing political winds.

This is the LEE mold I B/Oed (see link below). It's definitely for .300BLK. So is the MP mold that I have my eye on and that's an 8 cavity mold designed for production.

https://www.midwayusa.com/product/1010217751?pid=938614

I have this mould and it cast .307 with my alloy ( range lead + 2% tin ) and by the way , THIS is a BOAT TAIL type bullet not meant for a gas check .

[Forrest r]

Bought 1 of those lee 230gr bo bullet molds to play around with in 3 different 308w's. Never did find a load that was worth the powder I burned trying to find something that would work.

[popper]

Accurate 31-220D looks good for BO, just get PB. Profile of 31-185D works well in mine, just get longer body - it's similar to 150 GD ogive profile with blunt nose, Tom doesn't cut smaller than 0.18 meplat. I've heard the Lee does OK if GC added - the boat tail is a pain. You might consider a 2,3 or 4 hole mould. Even a 6x for rile is not much fun to use. Lots of bullets, lots of culls.
Look at the SAAMI chamber for BO, match close to that. The Rem & Win BO 220 nose runs good from an AR, others it a crap shoot. Bolt or single shot eliminates the feed problems so other ogive is OK. If small, PC - if large, size.

[BJK]

Thanks gents. I cancelled the LEE mold. I'm too new to this to have problems I'll need to try to figure out or to buy a mold that throws too small a D bullet for my lead.

[BJK]

I'm awfully hesitant about that big flat meplat on the Accurate mold Popper, but I bookmarked it.

Conditor, your NOE bullet is also bookmarked.

Anyone, would this mold be suitable for what I want?
https://noebulletmolds.com/site/prod...311-222-rn-k3/

[Burnt Fingers]

I'm awfully hesitant about that big flat meplat on the Accurate mold Popper, but I bookmarked it.

Conditor, your NOE bullet is also bookmarked.

Anyone, would this mold be suitable for what I want?
https://noebulletmolds.com/site/prod...311-222-rn-k3/

Maybe. That large bore riding nose might cause some problems in your chamber.

[AndyC]

I have this one, the Taco mold: https://noebulletmolds.com/site/shop...vity-pb-brass/

I bought it after watching this video: https://www.youtube.com/watch?v=x5aG-Nu9qis

[GoldieMI]

I have this one, the Taco mold: https://noebulletmolds.com/site/shop...vity-pb-brass/

I bought it after watching this video: https://www.youtube.com/watch?v=x5aG-Nu9qis

How do you like it?