How is the 25-06 doing as far as popularity? Does it have a solid niche in todays market? Are ammunition, components, and rifles readily available?

The reason that I ask is because I put together a rifle using a pre 64 action and the "used" barrel/components end up with a 257 Roberts with about .015"excess headspace over a NoGo gauge. This not due the action having wear, but an issue of mismatched parts. The barrel isn't caliber stamped.

I may just use it as is, may set it back, or may ream it up to a 25-06. It is a full length action with 30-06 box anyhow.

I think that the 25-06 is alive and well.

It is alive and well what caliber is the rifle now.

Ooops, fixed it. 257 Roberts with .015" over a NoGo gauge.

Just got a job in yesterday, new Krieger barrel, chamber to .25-06

You have several options.

1. You can use it as-is simply by necking down 7x57 brass and leaving a "false" shoulder for proper headspacing on the first firing. After that, simply back off your .257 die so that you don't push the shoulder back too far.

2. You can also run your .257 cases over an expander (maybe .277"), then treat them as above.

3. You can have the barrel removed and face off enough to properly headspace it for standard .257 chamber length.

4. You can run a .25-06 chambering reamer into it to convert it to a .25-06 (or even .25-06 AI if you wish). The .25-06 is probably more popular and more available than the .257 Roberts, so such a conversion would have no negative impact on your rifle's utility.

And since the barrel is not original, such a rechambering would have no impact on your rifle's market value.

Stonecreek really nailed all your options.
The 25/06 is alive and well and more popular than a 257 Roberts.
If I were in your shoes I would pull the barrel as Stonecreek suggests and face off enough to go back to a standard .257 Roberts. I happen to really like that round and it is very effective on Deer and Antelope for me and my youngest son.
If you have the hots for a 25/06 then ream it on out to that chambering.

You did not mention the barrel length. With a 22" barrel, I would stay with the Roberts.

It is 24 inch. It is a pre 64 Win 70 there is no "facing off a little" involved; it is a full turn then probably deepening the cone breech and extractor cut, and deepening the chamber.

For the record a friend had a pre 64 Roberts with .052" excess headspace. Believe it or not, the gun didn't blow the cases on factory ammo. .015" is about negligible as long as you don't overly resize the brass on subsequent loadings. I am leaning towards keeping it as is for now. I may warm up to a 25-06, but already have a few 30-06's.

I have 2 25-06's. Plenty of powder, bullets and loads available if you reload. Most gunshops will carry several brands/sizes of factory ammo to feed it as well.
Since you have it fixed, go ahead and enjoy the Roberts. If/when you shoot it out, or, if you start feeling you want something 'more', you can always re-bore to the 25-06 and start anew!

Both are great rounds and for the deer there in Pa, it should work just fine.

The 25-06 is plenty popular out west. Have talked with a lot of people that use them. Several of the kids I went to school with carried the 25-06 for both deer and elk.
I have a Remington Sendero in 25-06 and it has taken antelope, deer, and elk as well as a bunch of coyote.

I've owned three of them.....all on '98 Mauser actions. It's one fine deer round for sure.

My favorite caliber for antelope and deer.

Just off hand I'd say it has a better future than the 257 Robts..

In Todays America, I wouldn't make book on anything but a 30-06 and 270 for future brass and components, if that? I have never seen anything like what has happened in the last 4 or 5 years, and the big boys are blaming it on US for panic buying..Thats

Its manipulation brought on by a anti administration and the greed of ammo companies that make more money off selling loaded ammo as opposed to reloading components..

All the reason to not forgive Rem and Win. who will make no more brass for the next 3 years, and that's just a scam, they are out of brass making business, end of story! American shooters should start using PPU, Norman, RWS, Jamison and those that have not buckled under, and not buy Win or Rem products at all..