I recently acquired a pre 64 M-70, most likely an original 30-06, that had been rebarreled to 338 Win mag (Douglas barrel). I got it for 1/3 of the cost of an original pre 64 in 338 Winny.
The rifle had a muzzle break on it, and I detest muzzle brakes so immediately after I received the rifle I took the barrel off and took it to my Smith. I needed the threads cut off the muzzle and the barrel recrowned.
We noticed the breech was not coned. The rifle had been rebarreled like a Rem 700, with the bolt nose fitting snugly into a barrel recess. We reassembled the rifle and I noticed the bolt was a little hard to close. My smith looked and saw a rub mark in the barrel recess where the bolt was slighlty touching. So we took it back apart, put it back in the lathe, and he opened up the recess another .002." The bolt now feels as free as any other pre 64 and it feeds perfectly.
I have had Rem 700s set up very similar to this pre 64: tight belt headspace and tight clearance around the bolt nose. This is the first time I have seen anyone do that with a pre 64 M-70.
Since a picture says a thousand words, here is a picture of the bolt from the 338 on the left, and a bolt from a typical pre 64 M-70 on the right. If you look carefully, you can see that the right most lug on the standard Pre 64 bolt has a tapered face, where the 338 bolt has had the taper removed on it's right side lug. That creates a protrusion on the bolt that fits into a matching recess on the barrel.
One of the accuracy tricks with a Rem 700 is to machine the protrusion on the nose of the bolt to tightly fit into the recess of the barrel. As you can see, with a typical M-70 coned breech that isn't possible. However, this smith managed to modify the M-70 bolt so it had a protrusion that could be tighly fit into a barrel recess. He just had it a bit tight, so we had to enlarge this recess by about .002." This will still allow the accuracy trick to work, though pre 64s usually don't need such tricks to shoot well.
I don't know if the bolt protrusion is the reason, but this 338 Winny is the most accurate 338 I have ever owned.
The rifle had a muzzle break on it, and I detest muzzle brakes so immediately after I received the rifle I took the barrel off and took it to my Smith. I needed the threads cut off the muzzle and the barrel recrowned.
We noticed the breech was not coned. The rifle had been rebarreled like a Rem 700, with the bolt nose fitting snugly into a barrel recess. We reassembled the rifle and I noticed the bolt was a little hard to close. My smith looked and saw a rub mark in the barrel recess where the bolt was slighlty touching. So we took it back apart, put it back in the lathe, and he opened up the recess another .002." The bolt now feels as free as any other pre 64 and it feeds perfectly.
I have had Rem 700s set up very similar to this pre 64: tight belt headspace and tight clearance around the bolt nose. This is the first time I have seen anyone do that with a pre 64 M-70.
Since a picture says a thousand words, here is a picture of the bolt from the 338 on the left, and a bolt from a typical pre 64 M-70 on the right. If you look carefully, you can see that the right most lug on the standard Pre 64 bolt has a tapered face, where the 338 bolt has had the taper removed on it's right side lug. That creates a protrusion on the bolt that fits into a matching recess on the barrel.
One of the accuracy tricks with a Rem 700 is to machine the protrusion on the nose of the bolt to tightly fit into the recess of the barrel. As you can see, with a typical M-70 coned breech that isn't possible. However, this smith managed to modify the M-70 bolt so it had a protrusion that could be tighly fit into a barrel recess. He just had it a bit tight, so we had to enlarge this recess by about .002." This will still allow the accuracy trick to work, though pre 64s usually don't need such tricks to shoot well.
I don't know if the bolt protrusion is the reason, but this 338 Winny is the most accurate 338 I have ever owned.
