25x45 or 25/223
 

Anyone tried this one? I was researching 6x45 for hunting with the AR15 and came across someone offering the 223 necked up to 25. I know the 6x45 will push the same weight bullet a bit faster then a 223 but I don't know if the quarterbore will go past the point of diminishing returns. The other issue would be OAL in the magazine. Since I don't varmint hunt (at the moment) a 25 makes more sense to me, especially if I can use the same bolt, magazines, and cases like the 6x45. I don't mind handloading but would like to stay with more common components and spare parts then the .25 WSSM would allow. If you could get 250 Savage performance out of an 20" AR that would be plenty, that may be way to optimistic though.
TIA,
sharps54

If you can get your hands on "Wildcat Cartridges Volume II" it give a few defferent ideas on this. Most of the 25x47 brass is made from the .222 Rem Mag. case because of the longer neck. made with .223 brass, the neck is pretty short, the author go's on to state that with high velocity loads would in time erode the throat of the chamber.
velocitys in this artical range from
3,396 with a 60gr bullet
to
2,985 with a 100gr bullet
it doesn't give a OAL of a loaded cartridge so I can't help you out on if it will fit a AR mag.

Here is a link where this subject was originally discussed :
http://www.oa2.org/forums/viewtopic.php?t=7322

Welcome aboard sharps54

slightly modified 25-223 Rem.
 

Here is a photo of the 6.35x43mm wildcat. It is basically a 223 Rem necked up to 25 cal and shortened (~2mm) from 45mm to 43mm. I had to shorten the case a bit so when the bullets are seated deep enough to fit in an AR15 mag. the case mouth does not ride up too far on the bullet ogive.

CH-4D had a set of 25-223 dies in stock so I was able to put together several dummy rounds and see how they fit in an Ar15 mag. Others have had reamers made for this wildcat so the reamer drawing only have to be modified to accommodate the throat and lead. Kurtz gave me some suggestions and for throat and lead dimensions... The drawing is pretty much finalized, so on Monday the drawing and dummy rounds go off to PTG.... Hopefully, in about 4-6 weeks I get my reamer.



The reloading data for the 257 Kimber listed below should give one an idea of the velocity potential. I am going to build a 20" barrel for this cartridge so I expect to get velocities about 75 to 100 fps slower than those listed below.

257 Kimber (a.k.a. Copperhead) Barrel Length: 22"
Bullet--------Powder---- Grs.------Vel. (ft/s) Grs. Vel. (ft/s)
75GR. HDY HP---H335------28.0------2769---------31.5------3195
75GR. HDY HP---H4895-----28.0------2756---------31.5------3192
75GR. HDY HP---H322------28.0------2806---------31.5------3198
87GR. HDY SP---H335------29.0------2870---------31.0------3030
87GR. HDY SP---H4895-----29.0------2824---------31.0------3056
87GR. HDY SP---H322------25.0------2604---------28.0------2868
100GR. HDY SP--H4895-----26.0------2527---------28.0------2760



From Left to RIght.Black Hills 69g 223, 100g Sierra MK, 6.35x43mm w/100g Sierra MK, 100g Sierra GK, 6.35x43mm w/100g Sierra GK, 75g Hornady V-Max, 6.35x43mm w/75g Hornady V-Max, 85g Nosler Ballistic Tip, 6.35x43mm w/85g Nosler BT, 100g Sierra Pro-Hunter, 6.35x43mm w/100g Sierra Pro-Hunter, unloaded 6.35x43mm case, and Black Hills 77g 223.

Thanks for your time,

320pf

That looks like about a 100ft/sec gain over published 6x45 data.
That should be good for an additional 3-5% energy with the larger diameter bullet and about 35% more than the 223.

The reason I went 6x45 was the mass availablity and choices in bullets.
The .257 diameter has never really had a lot of bullet choices.

ar mag limit
 

Given the length limit of the AR15 mag, the bullet choice/weight is pretty much max at 100 gr.

I also shoot the 300 Whisper and I wanted a wildcat that did not require much case prep. but was looking for more velocity than the 6x45mm. The Hodgdon reloading manual indicates that a 75g bulllet in a 6x45mm tops out at about 2900-3000 fps. The ballistics for this wildcat should approximate the 250-3000 savage.... We will see.

Kutz's 25x40mm actually got me motivated to build this wildcat.

So how do you like shooting the 6x45mm?

320pf

I don't even take a 223 for coyotes anymore.... just the 6x45's
The energy difference is apparent

Have you tried the 6x45mm on deer size game? I would guess that the 6x45mm work pretty well...You are only giving up about 100-150 fps to the 243W or 6mmRem.

320pf

I haven't tried it yet on anything other than coyotes.
I primarily shoot 80 grain for hunting and 60 grain for targets.

In the 80 grain I am about 300ft/sec slower
In the 60 grain I am about 500ft/sec slower.

I am hesitant to use it on antelope or mule deer. We really don't have whitetail deer here. I guess I am hesitant because I also have a 243 that I use on those.

Well I finally got my 6.35.43mm (257/223) project together. Here are some early results:

Load Data: (standard disclaimer as with any wild-cat, use at own risk and work up slow)

100 gr Speer SPBT (16 inch 1:10 twist barrel)

23.0gr H4895 = 2294 fps
23.5gr H4895 = 2336 fps
24.0gr H4895 = 2350 fps
24.5gr H4895 = 2400 fps
25.0gr H4895 = 2463 fps
25.5gr H4895 = 2505 fps

75 gr Hornaday V-Max (16 inch 1:10 twist barrel

25.5gr H4895 = 2560 fps
26.0gr H4895 = 2600 fps
26.5gr H4895 = 2678 fps
27.0gr H4895 = 2728 fps
27.5gr H4895 = 2803 fps

I think that H4895 is a bit too slow of a powder for this cartridge. Also there is no way that I can get anything close to the amount of powder in this cartridge as that listed for the 257 Kimber. I have some IMR 3031 around to try but from the data posted by Kurtz on his 25/40mm I think that 1680 may be the best powder.

We will find out.


320pf