View Full Version : Re-Boring .243 to .257Roberts

November 18, 2012, 05:46 PM
I have an older Ruger M77 FlatBolt that I have to finally do something with and have decided to have it re-bored. Can anyone recommend a smith to handle it? I have lined up a couple but they are loaded with work and I'd like to get this knocked out.
Ive decided to open it up to a .25 Roberts. The rifling currently has seen its better day but I love the rifle and do not want to re-barrel and change the aesthetics.

Jim Watson
November 18, 2012, 06:09 PM
I don't think a .257 Roberts reamer will clean up a .243 chamber. It is much more tapered.

There is a wildcat .25 on the .243/.308 case or you could to to the .260 Rem.

November 18, 2012, 06:30 PM
I have never really looked into re-boring a rifle barrel. But i feel like the process of boring the entire barrel out to an entirely different caliber and re rifling the barrel is going to be not just labor intensive, but very very specialized labor at that. Its the sort of thing i wouldn't want to trust to anyone but a company that makes their own barrels to do it.

Its going to be expensive, like more expensive than buying a brand new barrel chambered in .257 Roberts and having it installed..

Why not just re-barrel with one as close to stock contour as possible?

You could get a brand new match grade barrel in the same contour and color for probably half the price it will take to get your old barrel bored out.

The barrel maker Lilja might do it, but they are just going to say exactly what I did even if they were willing to.

November 18, 2012, 06:31 PM
Good choice on going to the 257 Roberts. You might want to rebarrel. My barrel maker is out of business but I'm sure there some makers out there who could provide you with an excellent replacement.

November 18, 2012, 11:28 PM
A few issues:
* A 257 Roberts reamer will not clean up the 243 chamber, as already mentioned.

* A .250" bore may not fully clean up the .243" groove diameter of the 243 barrel.

* As already suggested, you would be better off going to a cartridge based on the 308 Win if you are dead set on reboring.

* You may be better off rebarreling, it will cost about as much as reboring and re-rifling, possibly less.

Bart B.
November 20, 2012, 07:23 AM
A rebored/rerifled barrel will never shoot as accurate as the original did. Rifling tools tend to make bigger groove diameters at each end of a bored and reamed barrel blank; they're belled a bit at their ends. Some top quality match barrel makers air or hole mic gauge their barrels and put a mark on their outside at each end where the bell starts. That's why 'smiths cut off the first inch or two of a new barrel's muzzle and the chambering reamer takes out the bell at the breech end.

I suggest contacting Ruger about getting a replacement barrel with the same contour so you stock will fit it. You could probably get two or three of them for the cost of having a smith rebore/rerifle your old one.

There's been a few 'smiths that relined a barrel with a rifled tube that's been fit to a shot out barrel after it's been gun drilled and reamed to a bigger hole. But usually for barrels using low pressure cartridges. My brother had his 16 gauge - 7x57mm Mauser three barrel drilling's shot out rifle barrel relined with a .22 K-Hornet chambered tube but he never loaded the ammo up to max SAAMI pressure specs; mild loads only.

old roper
November 20, 2012, 11:19 AM
I think Jim Watson is right about not having enough to rebore to a .257 Here is link


Here is another the old LaBounty reboring with new owners


I've had only one barrel rebored it was done by LaBounty in 308 Norma mag and it was chamber by him.

Most custom barrels can be made to match existing contours and length and you have to weight cost of new barrel vs reboring and where you save is having rifle rechamber by who's doing the rebore.

Mine was done in the 80's and I had better accuracy with the rebore and here is something from the Clearwater on accuracy

What kind of accuracy can I expect?
Each barrel leaves our shop with a bore that is consistent in diameter and twist rate with a fine hand lapped finish. These are two traits of many that contribute to accuracy, and the only two over which we have control. Reboring will do little to straighten a crooked bore (although some crooked barrels shoot pretty well). A bolt action that has an out of square bolt face, crooked barrel threads, only one bolt lug bearing, poor bedding or any other problems known to cause poor accuracy will not shoot very well even with the best of bores. If you are considering a rebore to correct an accuracy problem it is wise to eliminate as many other potential causes as possible before reboring or rebarreling. A gunsmith familiar with action accurizing/blueprinting techniques can identify and correct many problems. This will allow one of our rebores (or any good barrel) to shoot to it's potential. With this in mind, you may expect your newly rebored barrel to shoot as good as when it was new, many times they shoot better and almost always foul less. Performance equal to the better cut-rifled aftermarket barrels is common.

November 20, 2012, 04:22 PM
Barrel, .257 Roberts, 21-3/4", Blue



SKU: 978300

Our Price: $150.65


I bought one of these for a small ring Mauser and I get right at one inch groups at 100 yards.


November 23, 2012, 02:41 PM
Be sure and check the magazine length very carefully. I *think* Ruger built their 257 Roberts on a long action and your 243 is probably a short action.

James K
November 23, 2012, 07:47 PM
It always amazes me that folks discuss reboring and re-rifling barrels like it was done all the time on the kitchen table with an electric drill and a rusty can opener. Highly specialized and expensive equipment is required. There are not many shops capable of actually doing that work, and a gunsmith who says he will do it probably intends to outsource the work. Plus, almost always, the cost will exceed that of rebarrelling.


November 25, 2012, 02:48 AM
Get a new rifle. Thats like trying to put a LT-1 350 in a Honda Del Sol.

November 25, 2012, 11:01 PM
Why do you "have to do something with it"?

It's already a .243.

Whats wrong?

If the barrel is beyond repair Ruger will rebarrel it for you in .243.

They do a good fast job and don't charge much.

Otherwise just sell the rifle and buy another.

November 26, 2012, 03:44 PM
Savage99 is right, Ruger is the manufacture and you can sent it point to point without getting an FFL involved to reduce costs.