300/357

[BigEyeBob]

I had planned to build a 300 Sherwood rifle on a martini cadet action .My&# good friend who had a really sweet custon built 300 sherwood passed away just before Christmas I ended up buying a number of rifles from his estate one being the 300 Sherwood.I also have a early Francotte Martini in 300 Sherwood ,so I dont really need three of a similar action and same calibre.
So I have a .300" barrel (unchambered ) ,a nice clean Martini cadet action frame and enough parts for the internals. I have been entertaining the idea of necking the 357 mag down to take a 300 cal projectile . I would use cast boolits ,I have a mould that I modified to cast 140grnf projectiles with , but could also use the Lee 155gn 312" and size them down to .300 .I would have to make my own chamber reamer , and dies or get them made .
Any thoughts or ideas to add from the forum?

[LAGS]

That might be a nice round in an SKS or other rifle that shoots the 7.63x39.
Sort of like the old .256 magnum in the 30 carbine rifles called the Ferret.
You would have to build a new barrel like you are, but the bolt face will work.
Hmm.
Maybe rechamber an old 30 carbine barrel and modify the bolt face to make a .30 Ferret.
But your idea sounds workable for the Martini.

[Nueces]

This has been done. Paco Kelly made one like it for lever guns, with a long straight neck and gentle shoulder, like a super 32-20. I have the reamer. Cases are everywhere and forming means only a single trip through the sizing die. It is a super 30 bore round and one I'm going to use myself.

[Sean357]

I had a thought about doing this a while back. Staring at my 357 cases and a few 7.62x39 bullets during a bored moment. Had even looked up info and found the article that Nueces mentioned by Paco Kelly. Can't remember much about it now, but I'd still like to do it. Had no money at the time for the right barrel receiver combo or suitable lever action, but now that you've reminded me about this I think I'll start setting some money aside.

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[Sean357]

Can't find the info now, might not have been Paco Kelly.

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[357Mag]

Bigeye -

Howdy !

The .351Win SL has the same rim diam that the .310 featured, just not as thick.
The .351SL case is also a couple 10ths longer, and also is wider @ the base.

Extraction should be ok, in a rifle set-up for .310 to begin with.
Perhaps the difference in rim thickness would not be insurmountable ?

Just a thought.


With regards,
357Mag

[curator]

The "rimmed" version of the .300 AAC "Blackout" or .300 Whisper/300-221R is a .357 Mag necked to .300 just a hair shorter case length. Anything the .300 Blackout will do your design will do as well. Of course, the aforementioned cartridges are designed for heavy sub sonic bullets and are rifles with fast twist rates. Several after-market barrel makers who specialize in T/C Rncore and Contenders offer this chambering

[WALLNUTT]

Sounds like the 32 Miller short only 30cal. Should be a hoot.

[BigEyeBob]

Groove diameter on my barrel is .300" the twist is 1:14 .

[paul h]

The "rimmed" version of the .300 AAC "Blackout" or .300 Whisper/300-221R is a .357 Mag necked to .300 just a hair shorter case length. Anything the .300 Blackout will do your design will do as well. Of course, the aforementioned cartridges are designed for heavy sub sonic bullets and are rifles with fast twist rates. Several after-market barrel makers who specialize in T/C Rncore and Contenders offer this chambering

The rimmed 300 BO/Whisper et all is properly formed from 360 Dan Wesson brass, as it's a 1.415" long case and trimmed to length. The .357 mag being 1.290" long is more than a hair short, and the 300 bo doesn't have the longest neck to start with so the 357 brass wouldn't be the way to go IMHO.

[rockrat]

Or make a 300/357maximum

[BigEyeBob]

357 max brass is not easy to get here ,was never popular .Shipping brass from OS is very difficult due to restrictions put on by govt here and OS.Of course one option is to sell the barrel and get some other calibre or just put it in my stash .

[PaulG67]

This is a project I have been working on for a couple of years, it has been real slow, I want to get a commercially made reamer but they are not cheap. I have about 400 brand new Starline 357 Max brass that I bought years ago and have not used and a barrel that I am going to make for my contender, also one to make for my TCR-87 as I believe the caliber is well suited to single shots. This is what I am going to chamber in them.

I formed the cases by simply stuffing a 357 Max case in a 357 Max sizing die and then into a 30 Herrett sizing die which creates a neck of .290"-.295" in length, just right I think. I am going to attempt making a "D" reamer to chamber the barrels. I have one drawn up that I think will do the job just got to get out to the shop and make it however I am going to call PTG first and inquire if they have one or can make one.

[Der Gebirgsjager]

I like it, Paul. Should be a good cartridge. And, from past experience with PTG I think they're a good choice to make your reamer. Of course they'll want a couple of your finalized design cartridges to work with. Dummies without powder would be best.

[PaulG67]

I am sure you are exactly right Der. I just have to make the time to call them. I have a 357 Max reamer that needs sharpening I will ask if they can do that also.

[M.A.D]

Try running 357 max cases up into a 30-221 fireball FL Size die and trim... Makes a brilliant case and works great on a Martini. And end up with something like this ..

[garandsrus]

This has been done with both 38 Special and 357 Mag, the 38 is called the 30 Badger. Search on this site for posts about it.

[BigEyeBob]

what diameter projectile is used in the 30 badger ? .308 I assume .
Im talking a bullet diameter of .300" a true 30 cal.

[reed1911]

Yes, the Badger is a .308, but the same loads could be used with your .300/.357.

[mcdaniel.mac]

Try running 357 max cases up into a 30-221 fireball FL Size die and trim... Makes a brilliant case and works great on a Martini. And end up with something like this ..

I keep seeing this beautiful rifle, and I feel it would be a shame not to stop and say so.