Less Than 50 BMG .510 Rifle Cartridges

[Deleted member 46119]

Thanks looks pretty cool what cartridge is your wildcat based on and what actions are compatible with this particular cartridge? Thanks in advance for any and all thoughts,opinions,or answers.

It's based on a 505 Gibbs. So is mine but short. 2.6" case.

The loaded round is very long... While the will fit in a Mark V or CZ 550 or "custom". It will still be single load.

 

[375rifleman]

jfseaman ok you say that the CZ550 action will work. You also say that it would also be a single load (single shot) would having a CZ550 repeater in this cartridge even be a possibility? I like the idea for this cartridge but I also like bolt action repeating rifles. Thanks in advance for any and all thoughts,opinions,or answers.

 

[Topshot]

My THUMPER gets 2450fps easily with the 750gn A-Max at a loaded length of 5.050".
If you seated it to standard 505 Gibbs length that would be suitable for magazine lengths of 3.9 inches, the bullet would be too far down into the case.

So the only option for a magazine length of 3.9" would be to design a custom reamer.

You still need an action with the right bolt face diameter of 0.640" with Gibbs brass or go for one of the other case designs with a smaller case base diameter but this will cost you case capacity.

I have a usable case capacity of 148gn of powder with a seating depth of 5.050". Dropping the loaded length to 3.9" would reduce the powder capacity to about 100gn.
This might get you to your target velocity of 1800fps? There is only one way to find out.

Design your reamer, and have a go! Just like I did with my THUMPER.

 

[Deleted member 46119]

I'll have to do some scratching to figure out a design, coal and action that will magazine feed. It will give me something to do in the morning while I drink my coffee.

Swamplord knows better how long a CZ 550 can go. I know the Mark V will do just a bit more than 4 with some custom work. Stiller TAC 408 for a custom, someone here may know how long it can go.

 

[375rifleman]

jfseaman many thanks for anything you manage to come up with. I'm an open book I enjoy learning from the more knowledgeable/experienced members on this sight like yourself. I was thinking pretty hard myself about the applications of the many custom 505 Gibbs bolt action rifle actions (Lon Paul Custom Guns, Kilimanjaro Rifles, MNR Custom LLC, George Gibbs LTD, Granite Mountain Arms, Hartmann & Weiss, Heym USA , & Sabi Rifles) even though most of these are impractical simply because of cost. As well as the CZ550 Action.

 

[Topshot]

If you are buying an action just for this .510 project. I would get a Stiller 408 action.
Then if you want you can switch barrels and shoot a .375 Cheytac. .338 Snipetac, .408 Cheytac or any of the less common wildcats based on this case.

The actions come in two different diameters so you can build a lighter version if you want.

 

[375rifleman]

Topshot I recently read your post about your shortened "Thumper" and that really made me wish I had access to a neconos quickload load program to test your theory without having to make a custom reamer and development test loads. I realize that a computer program won't be exact but it could show any potential problems beforehand.

 

[Deleted member 46119]

Well, there's not much in the way of magazines between 4" and a full 50BMG.

That's a shame.

At 4" COAL, with at 28" barrel will do pretty exact to what you want. Even a little shorter.

A Mark V or CZ 550.

I'm going to have to look into bending my own magazines.

Dang it. Another reason to get the mill and lathe out of storage.

 

[hemiford]

Not to change subject, but, how long a COAL will the TAC 408 magazine
accept ? How long a cartridge can you single feed ?

 

[Deleted member 46119]

Not to change subject, but, how long a COAL will the TAC 408 magazine
accept ? How long a cartridge can you single feed ?

I couldn't find a magazine for it longer than 4" but the port is 4.4". Perhaps I'm missing something.

so single feed, maybe longer than 4.4"

 

[hemiford]

Thanks much, Mr Seaman.

From what I can gather, the longest C-T cartridge out there is C-T's own
419 gr 408, which is somewhere around 4.3~4.4 COAL. 505 Gibbs is right
at 4-inches.

I presume C-T's own magazines will hold this. I don't know where C-T
buys these mags. I also don't know much about the actions used in their
rifles. Info is hard to come by.

Reason I'm asking all this is for research on my next build. There are only
a couple of Gibbs-sized actions out there. I don't want to buy a complete
Chey-Tac rifle from them, and I'm not entirely sold on Stiller.

 

[Topshot]

This is not a real issue.

I can load to a COAL in excess of 5.100" in my Stiller 408 action without any problem at all.

The action cut out is more to eject the empty case anyway. I could load a 6" round into this action through the port if I wanted.

These babies fit.

 

[Deleted member 46119]

This is not a real issue.

I can load to a COAL in excess of 5.100" in my Stiller 408 action without any problem at all.

The action cut out is more to eject the empty case anyway. I could load a 6" round into this action through the port if I wanted.

These babies fit.

What magazine?

 

[Topshot]

No Magazine mate. Just single load through the port as normal.
If you want to got real long then remove the bolt and feed it from the rear.