I really like the Model 70 and I have built some pretty nice target rifles on Model 70 actions. I just don't think they are quite the equal of the 700.
As for the reasons, I think it is a little difficult to identify features which make or break the actions but I'll try.
Bedding surface. The 700 bedding surface is simple and on a single plane. It is round which may be a problem where the action is subject to much torque (fast twist barrels, rapid fire operation).
The model 70 bedding surface is complex, multi-plane and the base is located further below the centerline. The Model 70 offers greater resistence to torquing. I think the Remington come out ahead (mrginally) just because of the ease of bedding.
Concentricity: the Remington design is concentric. Although the Model 70 is more rigid, the Remington design might do a better job of transmitting forces from firing through the bolt lugs to the receiver. The fact that the Remington bolt lugs are slightly wider may also play a part.
I don't believe most gunsmiths do the same sort of truing operations to a model as they do to a 700 and some may not even be capable of doing so. If they did, the results might be closer than they often are.
I have a post -64 Model 70 which has been trued as well as I can do it (actually, all of my Model 70's have gotten the same treatment, with minor variations according to their intended purpose). The threads have been opened up to 1 1/16 inchx16 TPI (just like a Remington!), the locking lug seats re-machined in the same set-up and the receiver face trued; also in the same set-up. The bolt has been sleeved and the bolt face bushed. The locking lugs have been re-machined on their bearing surface. The action is bedded on a machined aluminum block which is glued into a Mac Millan stock. Theere is a skim coat of epoxy over the block to ensure even contact. This rifle has been a 6.5x55, a 308 and a 6BR. It has shot quite well in all calibers but has never quite been as good as I think it should be. It has been, in reality, a .4 rifle at best. At three hundred meters, I could shoot 200's but the x-count would never be over 12 or so out of twenty shots (this as a 6BR). 5 shot groups ran around .380 MOA. By the way, the rifle weighs about 14 pounds complete. I threw together a 6BR on a Remington 700 for a guy to shoot coyotes. I trued the receiver face and the bolt face and did nothing else. I bedded it into a factory 700 stock. This 11 pound rifle shot 5 shot groups also around .380. It made me want to throw rocks at my Model 70!
I recently shot a few groups through a 308 barrel which I screwed onto a trued 40X. It shot very well. Sub .3, mostly. (the 308's recoil causes me to shoot the occasional flyer) I put this same barrel onto a trued Model 70 short action and it now appears to be a solid .4 moa rifle. Now, in all fairness, there is a difference in stocks (BR for the 40x, Marksman for the M70) and scopes (36 on the Rem 24 on the Winchester) but I still feel there is a significant difference in performance which may not be attributable to these differences.
I have too much work in the shop to be able to do it now, but when I can, I'll try to run a more equal comparison. I can set two actions up the threads and headspacing are the same and stock them similarily. Maybe this winter.
By the way, centering the bolt at lock-up does seem to help the old M70 quite a bit. I got the impression it was good for about 1/8 moa of vertical improvement.
It may well be that the 700 got the reputation for accuracy, via the BR world, just because the 222 Remington came along with a Remington action and that action was easy to work with. Istill suspect the 700 has an edge though. That I continue to shoot some Model 70's is probably more indicative of a personality flaw in the owner than of the action's suitability. Regards, Bill.
