Quote:
Originally Posted by 320pf
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
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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
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