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Posted By: cole_k What is a .257 Kimber? - 07/22/10
I was looking at the Hodgdon Reloading Data Center today and saw reloading data listed for a .257 Kimber.
What is a .257 Kimber?
Posted By: DeerTracker Re: What is a .257 Kimber? - 07/22/10
just from a quick search i found something that said a 25/222 Magnum wildcat.
Posted By: Outcast Re: What is a .257 Kimber? - 07/22/10
Originally Posted by DeerTracker
just from a quick search i found something that said a 25/222 Magnum wildcat.
Wasn't that a cartridge designed by John Wooters that he called the .25Copperhead?

O
Posted By: Prwlr Re: What is a .257 Kimber? - 07/22/10
Originally Posted by cole_k
I was looking at the Hodgdon Reloading Data Center today and saw reloading data listed for a .257 Kimber.
What is a .257 Kimber?


The 257 Kimber was developed by Mike Hill of Washington State and introduced by Kimber in the model 84 rifle in 1986. It is the 222 Rem Magnum case necked up to 257, body taper reduced and the shoulder moved up. (Hodgdon Data manual No. 26).
Here is the best information available on the 257 Kimber.

It may be found on Pages 959-963 of Wildcat Cartridges - Volume II by Wolfe Publishing. The book is ISBN 1-879356-18-X.
Posted By: johnw Re: What is a .257 Kimber? - 07/23/10
the copperhead is the .222 rem simply necked up to .25... i believe that all of the small head cartridges have been wildcatted...

interesting to me how remingtons shop came up with the .222, the .222 mag, and the .223...
have used them all and the .222 is my hands down favorite, but i can give no rational reason for it.....
Posted By: johnw Re: What is a .257 Kimber? - 07/23/10
i purchased my L461 H&R with the intent to do up a copperhead...
having shot the donor, i can see no excuse for tinkering....
Posted By: cole_k Re: What is a .257 Kimber? - 07/23/10
Thanks guys.
Posted By: erich Re: What is a .257 Kimber? - 07/26/10
I read the article on the 257 Kimber and it realy peeked my intrest. I ended up building a 25-204 Ruger, a better selection of brass and no fire forming. I use the load data from that article for the 25-204, matches 250 Sav factory balistics and works just fine on deer.

erich
Posted By: Centex Bill Re: What is a .257 Kimber? - 07/28/10
I am potentially interested in the 257 Kimber. Where could I rent a reamer and get reloading dies.

Bill
Posted By: HawkI Re: What is a .257 Kimber? - 07/28/10
Hodgdon has data, I'd not rent a reamer and CH-4D should have dies, if anyone does.
Posted By: MarknMaggie Re: What is a .257 Kimber? - 03/14/23
So to risk reviving a 13 yo thread, and in a similar vein, what are your experiences with the 25-45 Sharps (6.35×45mm/223)? From looking at pics on the Sharps website, the seating of the 87gr Speer SP appears to be deeper than the bullet ogive in order to fit the AR15 magazine. If true, then the case is really too long for the projectile, right? Yet, I've heard and read so many good things about the 6x45 cartridge but maybe for uses in bolt guns & not an AR? I'm interested in easy 223 AR wildcat conversions (no bolthead change-barrel only) that have deer class capability. So, 6x45, Sharps (these two only need neck expansion),the 277 Wolverine, 300 Hammer (need shoulder setback, trimming, & annealing or purchasing of backordered preformed brass). Any other possibilities? -Mark&Belle
Posted By: Craigster Re: What is a .257 Kimber? - 03/14/23
Originally Posted by Centex Bill
I am potentially interested in the 257 Kimber. Where could I rent a reamer and get reloading dies.

Bill

I would contact Manson Reamers.

https://mansonreamers.com/
Posted By: keith Re: What is a .257 Kimber? - 03/14/23
25/204 is an option
easy to open up std 204 Redding S full length and Neck sizers, and bullet seater from Forster or Redding comp
Posted By: Craigster Re: What is a .257 Kimber? - 03/14/23
If you just to have a wildcat in 25 cal, the 250 Savage AI is the most practical way to satisfy you craving.
TAG
Posted By: MarknMaggie Re: What is a .257 Kimber? - 03/14/23
Keith, I'm using an AR and STANAG magazine. Max OAL 2.26"? The 204 is longer than the 222 RemMag. The 223 case is too long with long bullets in the larger calibers like 243, 257 264, 277, etc. to still fit in an AR15 magazine.
Posted By: MarknMaggie Re: What is a .257 Kimber? - 03/14/23
Craigster- I'm talking 223 Remington based cartridges here, for the AR15 rifle, not an AR 10. But, yes, a .25 Creedmoor/250Savage AI is a neat cartridge but won't fit in an AR15.
Posted By: Chrome Re: What is a .257 Kimber? - 03/15/23
25-45 Sharps or 25-223.

I have an AR with an 18" barrel that gets 2,625 fps with 100 gr Hornady SP. I had a T/C Encore with a 20" MGM carbine barrel that I was able to load past 2.400" OAL and was able to get 2,740 with Nosler 100 gr Ballistic Tips.

My Ruger RSI 250-3000 gets 2,780 fps with Nosler 100 gr Partitions out of an 18" barrel.

I've built several 6x47 Remington's which uses the 222 Rem mag brass, which sometimes is hard to find. Running the .25 Sharps is much easier due to the brass being so easy to load for.
Posted By: 5sdad Re: What is a .257 Kimber? - 03/15/23
Originally Posted by Prwlr
Originally Posted by cole_k
I was looking at the Hodgdon Reloading Data Center today and saw reloading data listed for a .257 Kimber.
What is a .257 Kimber?


The 257 Kimber was developed by Mike Hill of Washington State and introduced by Kimber in the model 84 rifle in 1986. It is the 222 Rem Magnum case necked up to 257, body taper reduced and the shoulder moved up. (Hodgdon Data manual No. 26).


Good lord! The .222 Magnum was introduced in 1958, and it took until 1986 for that vital slot, so wide that an elephant could be driven through it, to be filled?
Posted By: Jericho Re: What is a .257 Kimber? - 03/15/23
I believe I saw a custom Remington 788 in 257 Kimber many years ago at a gun show.
Posted By: SuperCub Re: What is a .257 Kimber? - 03/15/23
[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]

[Linked Image from i.imgur.com]
Posted By: Bugger Re: What is a .257 Kimber? - 03/15/23
Not sure what you’re planning on shooting with your 257 Kimber. I’d prefer either a 250 Savage or 250 Savage AI if I had plans on using it on deer.
I’ve had 223’s, 222’s, 204’s and a 7mm TCU.
I’ve been off and on looking for a fireball or a 222 Rem Mag. They would be in my eyes varmint cartridges. The TCU was only used on steel targets, I suppose it’d work on whitetails, IDK - not my first choice though.

If you’re planing to use it in an AR platform consider an AR built for 308 sized cartridges.

Love the 25 caliber cartridges.
Posted By: erich Re: What is a .257 Kimber? - 03/16/23
The 25-204 is a virtual clone of the 257 Kimber without custom dies or intricate case forming. Ive been shooting one since 2005. I was looking at the 257 Kimber when 204 brass was released and realized that the 204 brass was so close to the Kimber that it was a better deal to neck the 204 to 257. The 204 worked out so well that I built a 6mm-204 and 22-204 in 2006. Gary Readers 257 Raptor is the same às a 25-204.

PacNor chambered a 25cal barrel with a 204 reamer and cut the neck and throat separately to the dummy rounds I sent to them.

It is a little heavy handed with 75gr Vmax at 3150fps if your saving pelts on coyotes. The 100gr Partition at 2850fps is perfect for deer and I load the 85gr NBT at 3000fps for Javelina and antelope if I get a tag. 86gr bulk cast bullets over a pinch of 800x works great for small game.

For an AR I would think the 25-45 would work better with 85-90 gr bullets.
Posted By: OSU_Sig Re: What is a .257 Kimber? - 03/16/23
Erich, Is the OAL the same as the 204 Ruger?
Posted By: SuperCub Re: What is a .257 Kimber? - 03/16/23
I think I'd look at a 6x45 first if I wanted something like this.
Posted By: erich Re: What is a .257 Kimber? - 03/16/23
No, it isn't, I load the Partitions to 2.40. I've had the impression that it is too long for ARs, and 527s.
Posted By: Jason280 Re: What is a .257 Kimber? - 03/17/23
I have the .25 TCU version in a 15" Contender, use it mainly with lighter bullets.
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