eastbank said:i have a rem 40xb in 6x47 and its a easy wildcat to make, 222 rem mag case(204 ruger cases can be used) necked up in one step and ready to load. 60gr bullets at 3200fps and 75gr bullets right at 3000fps. eastbank.
That's the 6x45 - one of the best AR15 wildcats out there IMO. If I recall correctly it will throw a 90gr accubond at about 2700 and more or less mimic the supersonic distance of M118LR, and maintain enough velocity to expand out to about 400y depending on elevation. All without using any non-standard parts other than the barrel, and with none of the bolt, extractor, and magazine issues associated with overly large bolt face cartridges like the 6.5 Grendel.With the available powder capacity, seems like a 6mm would be a better fit for a .223 based wildcat.
I built a couple of Grendel/264 lbc's and yes they had some issues at first--but my understanding is that the platform has matured and they have been ironed out--what issues remain?I'm researching that cartridge now. I think it probably has the same issues as the Grendel.
technically the 6.5 grendel is based on 220 russian rather than x39... but the end result is basically a 6.5x39 there is the 25-45 sharps which is a 223 necked up to 243, which is somewhat similar to what you're looking for.I can't find one anywhere. Seems to be one based on .221, X39, and one or two others, but none off the .223 that will feed from standard AR mags. Seemed pretty odd to me. Wanted to make sure I wasn't missing it somewhere.
then you are certainly brave. I ordered special grendel mags. even though they use the standard mag profiles, the followers and feed lips are very different from factory 223, enough so that I can instantly tell the difference between the two.While not based on the 223 case, the 6.5 Grendel will feed from a 223 AR magazine.
(At least mine certainly does)
257there is the 25-45 sharps which is a 223 necked up to 243
Isn't that pretty close to a 25-45 Sharps?
I've developed some very good loads for my 25 x 45 with 90 gr gamekings. Sharp's is gradually developing and releasing new loads--I think they have a new 100 gr cartridge out. But like the 5.56 there's only so much space for a long bullet. I wish nosler made a 257 ballistic silver tip around 90 to 100 grs--I bet it would be stellar in the 25 x 45.The 25-45 gets good numbers, however, it has two or three main
limitations:
>The .257 Cal projectiles were designed mostly for higher capacity/velocity
cases like the .257 Roberts...and thus a higher expansion threshold.
>There are not that many .257 Cal projectiles with high BC's available...although this is getting better...
>Using full length .223 Rem. cases (45mm) in the 25-45 round limits which
projectiles you can use say 60gr. to 100gr. pills, the higher BC pills will not
properly seat in the case without trimming the necks down.
I do however like the quarter bore a lot and they do come close to the 6.5mm based rounds like the 6.5mm PCC round.