Need some help here... But this is dangerous with all you enablers here. I have always liked the 6.5 JDJ But also I am looking hard at the 6.5 X 30-30 I have heard a few arguments on the fact about 30-30 brass not as strong and also not lasting as long as the 225 brass. Other side is the availability of the 30-30 brass. Little more work to form,, Dies are pricey,,,
Ok Lets hear it. For or against.

Have you considered the 6.5 Grendel? Factory loads and should be very close to what you're looking for

I have a 6.5JDJ and a 6.5X30JDJ. Why you ask? They are like Pok?mon, gotta catch'em all. The 30-30 base cartridge does hold a little more powder, about 3 grains or so. The brass is "thinner" and would probably not hold up as well as the 225 Win brass with top end loads. 225 Win brass is available on Gunbroker.com but has been going as high as $2 per case. If you don't set the shoulder back too much during resizing, they should last for years. SSK data for the 6.5X30JDJ does exceed their data for the 6.5JDJ. My standard 6.5JDJ load uses a Nosler 120 BT pushed to 2400 fps. The data supplied for the 6.5X30JDJ has several loads with that bullet doing 2427 to 2580fps. There is the 6.5BRM from EABCO. It uses 30-30 brass and is supposed to be optimized for the heavier bullets (140 grain) by using a fast twist and shooting at a slightly lower velocity. If you're thinking about using 375 Win brass to make up for the lack of strength in the 30-30 case, better check availability and price. They are scarcer than hen's teeth and command a premium. My vote is for the 6.5JDJ, check Gunbroker.com for used ones that usually come with dies and some brass.

Franchise No I have not looked at the Grendal. Maybe I should.

Mech 8 Thanks for that info. I knew most of it and part of why I considered the 6.5 X 30 was that brass was easier to find than the 225 brass. And Also I had looked at the 375 brass but decided against that. At the same time I knew it was thinner and knew I might have to watch loads (top end ones)
Now what I did not know was about the 6.5BRM

BTW I did see that offering on Gbroker about the 6.5JDJ with some brass,,, But for used,,for 500.00 seemed steep to me.

FWIW, Going up in neck size vs down but I have been learning to fire form for a 35/30-30 since I did not opt for the expensive dies and 35 rem dies pull neck offset due to thickness variations. 30-30 brass is so plentiful was the main driver - 18 gr unique under dacron filler in contender barrel. Tried 10 grains but it was not enough pressure. Brass formed very well. Is the 6.5x30 basically the same as 25-35? I would think 25-35 brass would be a good starting point to fire form to the chamber.

I looked and looked some more at everything, and made up my mind to go with the 6.5BRM from E.A.Brown. I think that is going to suit me better than any of the other 6.5 calibers.