243 Catbird

[andrews1958]

Does anyone have one? How do you like it? Grain bullets used? Is the spead as fast as claimed? I heard it is a real barrl burner?

 

[Knotwild]

I used to hang out years ago who made them. I can't remember, but I think Layne Simpson came up with it? I remember it as fast and flat, and that was before Berger hit mainstream. I also remember that it consumed barrels like I do a good fish sandwich.

 

[jackieschmidt]

This is one of Kenny Jarrets creations, they started with a 270 Winchester case to get a little more neck length. It s basically a blowed out 270/6mm with a 35 degree shoulder.
Of course, that much powder behind a 6mm bullet bullet is going to be a tad harder on barrels Regardless of the hype.
unless the laws of physics gets repealed, you want to push 70 grain bullets 4100 FPS, something is going to suffer.

 

[NZ_Fclass]

Seems like a difficult way to make a 240 Weatherby.

 

[TAJ45]

Seems like a difficult way to make a 240 Weatherby.

Can't really disagree there BUT, the brass is cheaper and lots easier to come by.

 

[NZ_Fclass]

Can't really disagree there BUT, the brass is cheaper and lots easier to come by.

But the dies are not and I expect a rifle in a rare wildcat cartridge to not be worth too much when you have finished building it - and is the performance any better than a 6mm Remington, if one used a proper barrel twist?

( said he, just building a 6mm SLR....)

 

[Kurz]

Everyone has an opinion...

Here is a Case:

243 CATBIRD​

The .243 Catbird was designed as an ultra-long range 6mm varmint round. It is based on the .270 Winchester case necked down to .243 and blown out with a 35 degree shoulder.

From Jarrett's site:

.243 Catbird​

68-70 gr. bullet ................... 4100 f.p.s.
85 gr. bullet ........................ 3800 f.p.s.
95 gr. Nosler Partition ......... 3500 f.p.s.​

The .243 Catbird was conceived to be an ultra-long range 6mm varmint round, but also works quite well for a deer cartridge. It is a .270 Winchester case necked down to .243 and blown out with a 35 degree shoulder. This case is delivering some impressive velocities. Our original goal was to get 4000 f.p.s. with a 68-70 gr. bullet. However, we surpassed this goal with 4100 f.p.s. We were able to achieve 3800 f.p.s. with an 85 grain bullet and 3500 f.p.s. with a 95 grain Nosler Partition. This cartridge packs plenty of punch for long range varmint hunting or medium range deer hunting.

Cases for this chambering are quite easy to form. You simply run a .270 Win. case through a Catbird full length sizing die, load it with a reduced load and fire-form it by simply shooting it through your gun. There are two versions of this cartridge. One of them has a tight neck and the other has a standard neck. The cases for the tight necked version must be neck turned before they can be loaded and fired. Once cases have been fire-formed for either version they can be reloaded as any other cartridge. While this cartridge may not be for everybody, many people will love the high velocity and the accompanying flat trajectories that can be achieved. This round may be the fastest 6mm. cartridge ever developed. Of course, you have to give something to get something. She is a “barrel eater” -- expect about 1500 rounds of good accuracy.

 

[andrews1958]

A very impresive caliber. Looks like it is similar to a 220 Swift that shoots heavier bullets

 

[Keefe300]

This is an interesting cartridge. I looked at this and the 6-06AI before deciding to build a 6mm-280AI. Decided to go this route due to factory brass for the 280AI. I can neck the brass down and no fire forming needed.

 

[CJ6]

With the listed ballistics .... It's nothing a 6-284 can't do.

 

[Frankm]

Keefe300, we did same thing, use 280AI brass and neck down and not have to fire form. We are running .272 neck so turning brass but still not FF ing definitely saves barrel life!

 

[Kurz]

The 6mm-284 has a 35 degree shoulder and about the same capacity when a bullet is seated. It's easy to neck down any one of the better brass manufacturers for this variant.

The Berger 105 gr. VLD Hunter bullets perform quite well in a DBM set up for the 2.925" OAL for feeding from the magazines.

There is very little if any real different between this variation and the 6mm-06 AI variation.