I got the dies and 70 grain bullets today. I made some magazine function dummy rounds but I can't really check anything till the barrel gets back with the pinned flash hider (short barrel). I figured I'd try them through a Pmag. The rimless 256 Winchester Magnum next to a .223 Remington round.
I'm not sure what the final exact size will be since I just got the dies and the barrel is not here for me to check headspace, etc.
Last Edit: May 10, 2011 17:48:33 GMT -5 by 22boomer
Cut some brass down and sized in std 256 Win Mag dies. Also did a full length .223 case.
Now just need a reamer..... and some time......
The 256 Rimless / Ferret / Universal could be a fun round, but bullet selection will be key for performance. QL shows 2940 fps with the Hornady 60gr bullet with M1 Carbine length - at 5.56 pressures of 62KSI. Any larger bullet and you get below the neck, reducing powder capacity. Maximizing capacity with the Hornady 100gr SP puts us at 2.030", and the ability to run stock mags, and will hit 2200fps + with 4198 powder. We did that with the Tok Mag (9mm Mag brass). So this round is another one of the "why not" conversions...not going to do anything we haven't already done performance wise. As an interesting "what if" the same bullet in a full length 5.56 case shows the bullet is below the base of the neck reducing capacity, but we should be able to grow the 256 case .250" and gain something, whether it would be worth the effort or not. But, as we all remember, we just did that with the x39 case and the 257SS and 257 ARS
QL does not accurately grow cases in the program to do comparisons, so when I get some time I'll use Quick Design to modify a full size 5.56 case to .257 bullet and import back to QL and see what it looks like.
Fun Fun Fun
Did a Quick Design 5.56 necked up to .257 with no other changes. Max bullet wgt is a 75gr flat base to keep from going below the neck. QL shows just over 3000 fps with 75gr bullet and 24.5gr of 4198. 60gr bullet can hit well over 3200 fps
I got involved with the rimless 256WM some time back and I like the little round although I can't say it's any type of super replacement for some other cartridge. My barrel is only 11.5" long but I can get 2500fps using the Sierra 70gr blitzking bullet and Lil' Gun for powder. Actually got it up to 2600fps but had high pressure signs. COL is 1.85" on my last bunch of rounds. I use a 20 round Pmag with a little block in the front to allow a full magazine and smooth feeding.
You can do nice machine work and could probably get the barrel extension to accept those 60gr flat nose bullets but I had zero luck -- that's the reason I used the 70gr Blitzkings. I would like to see what this little round would do in a 16" barrel. Longer, heavier bullets might work nice in a standard mag without any block in front. I hope you have fun with this cartridge. I got the barrel from another gun fellow that didn't have time to play with the round. It was originally meant to be something like the Knight's PDW round (6X35) and be used in something shorter and lighter than the M4 carbine. I can't make stuff like that but I sure had a lot of fun shooting this stuff -- it works really well in my AR. What I had hoped for was that I could find a 60gr bullet similar to the 70gr Blitzking in shape but I found the choice of light bullets in 25 caliber really stinks.
Another company makes special bullets in 25 caliber but they are super expensive. They have removable tips and they are designed so they can even be put in the cartridge with base facing out. If I could afford them I would have turned some of the top off to lighten them to get the 60gr bullets I want but they are priced like they are made of gold. See them here cuttingedgebullets.com/cgi-bin/commerce.cgi?preadd=action&key=ESP_I70_RAPTOR
Last Edit: Oct 20, 2012 17:24:30 GMT -5 by 22boomer
Hey 22B, it thought I might just be typing to myself all this time. Yes, I saw those bullets in Midway catalog; cool but expensive. I made some VLDs for the tok from solid stock so maybe I'll try some for the 257. Next time I place an order from Manson I'll get a reamer coming. Speaking of PDW - been playing around with that idea too.....
With the velocity I could get out of an 11.5" barrel with a 70gr bullet I would love to see a 60gr spire point -- I'll bet that would haul butt. I had thought about making a die and press to see if I could reform the 60gr flat nosed bullets but I don't have either the money or the talent to do that.
I really hope this all works out -- no telling just what Obama's plans are for all the semi's that owned by civilians. I hope it's just another ban like Clinton did -- it just eliminated the flash hider and bayo lug from my DCM service match rifle. I sure hope they come to some realization that the problem is all the nutcases and somehow they need to be identified. I sure hope things work out for you.
Will get to the 256 when I get a chance. As far as the "next Ban" it is going to be interesting. I hear Sen Diane Fienstien introduced a bill to make all tactical arms Class III requiring them to have the tax stamp of $5 - $200 each. So keep your ears to the ground and make sure your elected officials know how you feel. Main issue will be is this is a hot button issue and the next election is not for 18 months. Politicians will hope we have short memories unlike 2010....
Ordered a couple blanks in 1:14 and 1:10 twist to work on the 256WMRimless and our 257 ARS. The 257 clearly liked the lighter weight bullets with the 1:14. Pulled the 256 Win Mag into Quick Design to play with some lengths also. This one has been on the back burner for along time along with a number of projects but hopefully in a few weeks we can get some progress. The M1 Carbine mag adapter will handle these rounds up to a point. The selection of lower wgt bullets is going to come into play here. Lets see what happens in the next month or so.