30-360 DW or 300BO rimmed

[blackbahart]

was doing some pondering for a 30 cal rimmed for a martini.So ran a 360 DW case into the 300 die and it shaped up kinda purddy
so in effect basically a 300 BO rimmed .Chambered the 30 cal barrel with the BO reamer ,cut the relief for the rim and installed on the lil martini .Did some test firing today for function using BO data and she functioned flawless
made a file trim die to size the brass
seems to be nothing new but a fun project to do in the cold ,will mount scope and test for effect when it warms up some

neat project and no need for special reamer nor dies .

[Jedman]

That is a perfect cartridge for a Cadet rifle ! I used the 300 blk out platform for a break action 410 shotgun that I relined with a 30 cal liner with a larger diameter chamber OD. Since the shotgun would be dangerous with the pressures that the standard blk out run at I shortened the dies by .060 and form the cases on 357 mag brass and it makes a nice shortened rimmed cartridge that I load lightly.


Jedman

[Silvercreek Farmer]

Very nice!

[wmitty]

Neat cartridge! Sort of a 30 badger on steroids.

[wmitty]

Neat cartridge! Sort of a 30 badger on steroids.

[cwlongshot]

I have read if the idea and LIKE IT!

Only I wouldnt shorten the case. No reason for that extra step. Use a FL Maxi case or a european rimmed case as your parent case.

BO is limited cause of the AR-15 magazine length. You have no such limitation.

I know of some guys who simply had a rim cut done to a maxi chamber. That gun fired both rimmed and rimless BO cases. 357 Mag worked too just had a short neck.

CW

Edit: I like the lil 300 allot. But Id absolutely go FL if this was me. Its easy to load down hard and unsafe to push too hard. There is no replacement for displacement.

[BABore]

Neat cartridge! Sort of a 30 badger on steroids.

I had Manson make up a reamer for this about 3-4 years ago called the 300 BBS. I shove the 360 DW case into the same Redding 30 Luger/7.62 Tok die I use for the 30 Badger. No trimming required. I have only used it loaded subsonic to date. I do have a bunch of test rounds loaded up with Nosler 125 gr. BT's to see how fast it will go.

Another reamer was made without the rim feature so we could cut a rimless version. It used 223 cases in the same die set and was chambered in a couple AR's.

[Dinny]

I had a rim counterbore cut back in 2014 on my 300 BLK Handi rifle. My chunky, arthritic fingers prefer grabbing a rimmed case from the chamber, especially when it's cold outside. I nicknamed mine the 300 Dinny Rimmed (DR). CW was nice enough to get me started with some converted 357 Mag brass, but nowadays I convert DW brass and leave the trimmer set up for my 348 Win brass.

Thanks, Dinny

[barrabruce]

DW Brass for it over here seems less common than unicorn droppings.
I could get some 357 max brass for a price.

Wouldn’t you be near 30-30 Wesson territory?

I may have to stick to 357 mag brass and shorter chamber form.
Call it the 300 blk rimmed short magnum..
Seeing that the 22 magnum is mo better than a stinky ‘ol hornet.
It could kill charging buffalo with a name like that
Ha

[Silvercreek Farmer]

How does it compare to a 30/30 in terms of case capacity? How many PSI for the Martini action?

[barrabruce]

222 rimmed 42 000 psi
Or 357 mag or max.
25-30/30
How much do you want to be kicked around and how much trouble you want to load a round.
You need some taper and they have little extraction leverage.
Still most actions are 100 years old as well.
They are a nice little jewel of an action thou.

[Jedman]

I shortened the rimmed blk out version for a reason in my rifle. It is built on a Yildiz folding 410 shotgun that is super lightweight with a aluminum alloy receiver. I originally chambered it to 32 H&R mag. But somehow the chamber came out bad at the case mouth it was out of round and fired cases were hard to extract. The gun is not suitable for high pressures and I wanted to keep the cartridge as small as possible so the shortened bulk out fit the bill. It is a hand loading only cartridge and I load it light to keep primer flow from binding up the opening of the break action and it keeps someone from being able to chamber a 300 blk out in it and close the action.

Taking .060 off the bottom of the sizing die pushes the shoulder back and lengthens the neck so formed on 357 mag brass it works out well for my use.

Jedman

[blackbahart]

the reason I am trimming the case after forming from 1.4 to 1.368 is I do not have a neck reamer and was done on a kind of a whim .
I could have deepened the chamber by.032 also to avoid case trimming also ,but I thought of that during test firing
I would like to say I had a good reason ,but I don't .

quick load used to make up test ammo
barrel is a gain twist 24" 14 to 8
110 soft point privy 17 IMR 4227 34,803 psi at 2150fps
150 #3031 HNDY 17.5 IMR 4227 40,227 psi at 2000 fps

well with in the capabilities of the martini and will know more when I target it ,currently -40C here first one then the other in *F,,,, LOL
here is a pic of the martini ,just realized they all look the same just vary in wood and optics LOL

[barrabruce]

Please let us know how it goes when you get to test it out.

How does one extract a case when it is stuck in the cadet action from firing pin hole extrusion?
I haven’t had trouble yet but if I load one up ; well you know.
I have seen dings in the top of the swinging block on some thou.

[blackbahart]

I always bush the firing pin holes to .060 so the primer flow is avoided and cci 400 primers .My 5.6x50 was my first binding with the primer flow so now I always bush them now
looks like a few more days of -30C highs, supposed to break on Monday to more normals and should get out to fire for effect and crony the loads
put some 110 gr sp together too ,more apt to use them as more affordable than the 150 gr to test also