Last night I was pondering the benefits of a 6.8-30 RAR the 30 RAR is designed to shoot 125 grain bullets @ 2800 FPS but at the cost of BC. That is a weight better suited to the 6.8 for range, trajectory and velocity. 115 grain 6.8 bullets at around the same velocity or heavy 150 grain 270 bullets could make it interesting. Yes, when you neck down you get pressure issues but would a 7MM or 6.8 be worth it?

Fine for hunting but the mags have very low capacity due to the 284 Win diameter case that won't doublestack.

Was thinking this would be for a 30 RAR barrel swap so same mags and capacity.

I have the 30 RAR and will be loading lighter bullets such as 110 for it, I think that might make more sense. I would say instead of wildcatting to 6.8 I would get one in .260 Rem and have a superior round

Why not go straight to a 6.5mm instead and gain BC?

30 RAR necked down gives around 43.5 gr.

I've never looked at an RAR magazine but if it's possible to increase the cartridge length a tength by using cut down 284 Win brass then the capacity is 47.5gr and still have room for most 270 bullets.

Thanks for the numbers. 284 brass is thicker though isn't it?

Yeah I remember Constructor, a smith that chambers several wildcats for the AR, saying a while back that the capacity difference between the 30AR case and the 308 based BRX was very little because of that.

Load From a Disk actually gives three different case thickness for various wildcat versions of the 284 Win and I chose the thinnest one. Different brass manufacturers maybe? If I used the thickest brass the capacity shrinks to 41.4 for the 6.8 RAR and 45.2 for the .10" longer version.