Cast Bullets, the .30-06, and Going Heavy

[Bigslug]

Been wanting to do something like this for years, but it took a couple of side roads for the knowledge and opportunity to come together.

And yeah. . .I'm still trying to lure Zee to the Dark Side with bullet casting. Even if this project doesn't do it, it will be fun to bring you along for the ride.

THE FIRST PROBLEM: Cast bullets cannot be thrown as fast as jacketed for several reasons. One of them is an "RPM threshold" caused by your rifling's rate of twist that exceeds a cast bullet's material capabilities. Without getting into the weeds of the technicalities, all we need to know for this discussion is that with the industry standard 1-10" twist for factory .30-06 barrels, the wheels usually come off your accuracy cart somewhere above 2100 fps when shooting cast. There are guys going significantly faster with custom slow twist barrels, but as I'm shooting a lot of historical toys, here we are.

THE FIRST SOLUTION: If you can't throw something fast, it stands to reason that you should compensate by throwing something big. There are a lot of good 200 grain .30 caliber bullet molds out there. I have several. . .

BUT WHAT I'VE REALLY WANTED for years is 220 grains. It's the original FMJ bullet weight for the .30-06 / .30-03 left over from the pre-spitzer and .30-40 Krag days. Yeah, it gives up some trajectory (I do that with 2000 fps cast bullets anyway), but it has the potential to gain a lot of penetration. This takes us into the territory of W.D.M. Bell using his 175 grain round nose 7x57's to hunt elephant, so there is - admittedly - a boyish desire to create Walter Mitty's Dangerous Game Rifle here. Which brings us to. . .

THE SECOND PROBLEM: 220 grains fills up a lot of room. One of the tenets of cast bullets in bottlenecked cases is that you want your base and lube grooves enclosed in the bullet's neck and not creeping back into the powder chamber. On a plain base, this prevents erosion of the nice sharp edges of the base that you want for accuracy, and on a gas-checked bullet (which we're using here), it keeps a poorly-crimped check from falling off into the case. That's the hard limit for seating depth on the back. The hard limit on the front of course is where the bullet contacts the lands when chambered. Standard groove diameter for American .30 cal is .308", and with cast, we usually size our bullet shanks between .309" and .311" for good sealing of the barrel. BORE diameter, however, is .300", and you have to make sure that your bullet stays enough below that diameter in the nose to be able to chamber.

And yeah. . . it also has to fit in the magazine.

THE SECOND SOLUTION: So I got in touch with Accurate Molds and did some back and forth to custom-design THIS:

31-225A Blueprint.jpeg (106.1 KiB) Viewed 130 times

What we've got here gives me very nearly the .30-06's max overall cartridge length of 3.340" when seated with the gas check at the back of the case neck. The front-rear length of the gas check cup and the taper at the front of the .310" driving shank and .299" nose (A.K.A. "the bore-ride section") give me a little play, but it took some serious farting around with other bullets across multiple rifles to figure out where all those diameters and lengths wanted to be.

So, I was pretty darn giddy when this showed up:

31-225A Mold 2.jpeg (107.76 KiB) Viewed 130 times

I've come to like iron molds. Heavier than aluminum; not as heavy as brass; yeah you have to oil it to prevent rusting in storage, but the output is nice. . .so very nice!. . .Hmmm. . .possibly out of room for pics on one post. Let's try a second. . .

[Bigslug]

As I was saying. . .output:

31-225A sized & unsized.jpeg (51.25 KiB) Viewed 127 times

31-225A Loaded.jpeg (75.33 KiB) Viewed 127 times

Straight out of the mold and with a gas check crimped on and base sized to .310", ready to be tumble lubed. Sample round loaded to just shy of max .30-06 COAL.

Plan is to try IMR 3031 for the initial load workup as I have it on hand not doing much else, and it's got a widespread following as a cast bullet propellant across many different cartridges. If that's a dud, we'll try others. Outcome to follow.

[PFD45]

This should be interesting.
Good science!
Will those work in a magazine or single load?

[CPJ 2.0]

I like that. Would be pretty nifty in a .300 blackout.


And Zed will NEVER cast bullets. Ever.

[Bigslug]

Will those work in a magazine or single load?

Magazine. There was a fair bit of work done to ensure it. I've got a 200 grain mold with an almost identical nose that I made test rounds with. I seated them WAY out long; the driving band that far forward wouldn't allow the bolts to lock up, but it did allow me to test feeding of the nose profile with max allowable COAL / magazine fit.

My pre-'64 M70 had some issues feeding from the left side of the magazine (flat nose ran into the right side rear of the chamber entrance). . .until I swapped in the follower from my Hawkeye. Another Hawkeye follower is on order from Ruger. . .

[Bigslug]

And Zed will NEVER cast bullets. Ever.

I think he's somewhere between this:

Luke INJY.jpeg (17.76 KiB) Viewed 118 times

...and this:

Luke NOOO!.jpeg (20.31 KiB) Viewed 118 times

[Bigslug]

I like that. Would be pretty nifty in a .300 blackout.

If the current suppressor/NFA fight continues to go well to the point that we can own that stuff in CA, you can bet your ass I'll be looking into a Blackout bolt action. As it stands, I've not yet had cause to really geek out on it's chamber dimensions.

But the cool thing about Accurate Molds: you can find a blueprint you like in their catalog and request that they lengthen here, shorten there, add or remove a gas check shank, set the base and bore ride diameters to be what you want with your alloy mix, etc...

I own a bunch of NOE molds and they are (usually) great for off-the-shelf, standard dimensions drawn up around known cartridges, but for old, weird, and unique, Accurate will make what you want, so long as it's not a hollow point or base and you can live with a non-pointy nose meplat of 0.18" or bigger. They've got blueprints for the French Chassepot needle rifle, the Civil War Maynard, the stock chamber throat for the .348 Winchester, percussion-to-catridge conversion Colts - pretty much name it.

[Zee]

I like that. Would be pretty nifty in a .300 blackout.


And Zed will NEVER cast bullets. Ever.

Nope.

[Bigslug]

I like that. Would be pretty nifty in a .300 blackout.


And Zed will NEVER cast bullets. Ever.

Nope.

I play with 800F molten metal, you play with poisonous snakes. We've all got our kinks.