ORIGINAL: geoffh
I had a Rem700VLS in 6mm (same case as .257 Roberts) that was a short action. What I found wasa bullet loaded out to just off the rifling would not fit in the magazine. That tells me factory ammo has a pretty short overall length and, although I don't know about the .257 for sure, could be a hangup as far as shooting tight groups with factory stuffis concerned.If ammo is designed to work in short actions, as well as long actions, then there may be long jump before the bullet engages the rifling. I've never seen that work real well for good accuracy. Just a possibility, but there are a few rounds that are made 'short' so they work in all guns.
Right on! The .257 Roberts, despite having a 57mm-long case just like the 7X57mm and 8X57mm, was
SOMETIMES made by U.S. factories on short actions instead of the size they should have used! So the ammo was usually always loaded short (
taking up a lot of powder space from the case) to fit in the undersize magazines.
Generally, whenpeoplemade up custom .257's, they used actions of the right size then had the chambers throated long (
CORRECTLY!!) so the bullets could be seated out where they belong, and gotbetter accuracy AND MUCH HIGHER VELOCITIES than they could get from the too-short factory ammo. (This too-short factory ammo may be contributing to your problem.)
So, perhaps you have a long (correct) throat and a short action! If so, it
may work out that you have to use your rifle as a single-shot with ammo that is too long for your magazine to get the most accuracy out of it.
I don't know which length of M77 action Ruger uses for their .257's. I have a 7X57 M77, and it is on the same length action as their .30/'06's. But I once ordered a replacement magazine follower from Ruger for that rifle, and they sent me a short-action follower. So maybe Ruger doesn't know either.........