I'm thinking about having a M70 re-barreled to 6.5x.284. I plan on using this rifle for mainly target/varmit shooting. Possibly antelope hunting to.
With 120-140 grain bullets. I know this is a hand loaders only cartridge, which is o.k. Formed brass is available . I'm looking for information on what ratio of barrel twist is best for the 120-140 gr? Any reloading info or just general hunting/shooting with this cartridge is also appreciated.

I'd use a 1:9" twist.....further I'd go with the 6.5-06 over the 6.5-.284.

Hornady's fifth edition has loads for both cartridges.

I should have mentioned that the M70 I will be using is a short action (.308). The gunsmith recommends a 1:10".

I like 1 in 9 for heavier bullets, especially since you plan to use this as a dual duty caliber. For target only, 1 in 10, would work. I also was going to go down this road and changed my mind. Might later. I believe you make a good choice. I see people do some amazing things with this caliber at 1000 yards. Seems to be a breeze to reload also compared to long actions.

My Cooper will have a 1 in 9-twist rate. Cooper recommeds a 1 in 9 for 120 to 140 grain bullets.

Looks like I'll go with 1:9 twist. I suspect I will be useing 140 grains the most.

You started any load development yet?

I have not started any load development yet. I hope to get a load from Cooper when I get my rifle. I talked to them when I ordered my rifle. They said they would include load data for me. I plan on shooting 140's & 120's. I hope the 140's don't take up too much room in the case?

Wolf killer,

Went and seen the smith (Harry McGowen) over in St Anne, ILL (he used to run an add in Shooting Times). Took the Win M70 7mmSTW to have a Timney trigger put on and glass beded. I talked with him about twist rates for the 6.5 he usually goes 1:8 or 1:10. So I guess this muddies the water a little bit for me!? He showed me the Button rifleing method....pretty neat and fast, good finish on the bore. I will probably go with the 1:8 since I like 140 grain 6.5 bullets for their penetration.

Me too!? The 6.5x.284 has a slightly longer case than the .308. I too was thinking about having to seat bullets deep in the case[:'(][&:].

What ya plan to use your Cooper for? Hunting what? target shooting? Those are sure nice rifles....I thought about a .17 Remington or .220 swift on a Cooper Varmit extreme...could not afford it and an elk hunt though.

I was told by a rep at Cooper the 1 in 8 twist rate was the best way to go with 140 grain bullets. He felt the 1 in 9 twist rate would be a good match for 140 & 120grain bullets. I told him I would be shooting 120 grain bullets for antelope & deer hunting. Have you seen how long a .264 - 140 grain ballistic tip bullet is? Just from the looks of them, I doubt I will be shooting them much? The 140-grain bullet is going to take up powder space.