View Full Version : rechambering?

January 18, 2014, 08:58 PM
Hi I was wondering if you all could answer a question for me. Can a rifle be rechambered from 300 win mag to 30-06?

Willie Lowman
January 18, 2014, 09:21 PM
They can be re-barreled. .300 win mag can also be loaded down to 06 power.

January 18, 2014, 10:00 PM
The head of the 300 Win Mag is much larger than that of the 30-06. Not only would you have to get a new barrel but you would also have to get a new bolt. I'm betting it would be cheaper to buy a new gun once you got done purchasing all the parts then paying a gunsmith to assemble.

January 18, 2014, 10:07 PM

Welcome to TFL !

Short answer: "No".

Rechambering is only successful when the new reamer is larger than, and will totally clean up the existing chamber - IOW, the rechambering must be for a larger cartridge, not smaller.

The .300 Winchester Magnum:

Has a larger/fatter case than the .30-06

Has a (larger) belted case - which in turn requires the bolt face be larger than a .30-06 boltface.


January 18, 2014, 10:39 PM
I agree with AllenJ, it would probably be cheaper or about the same for you to sell the current gun you have now and just buy a 30-06. Plus you end up with a brand new rifle.

January 19, 2014, 12:12 AM
Depending on barrel taper, it could be possible to cut 2.6" off of the breech, and rechamber to 30-06.

I know long range high power competitors, will cut off enough to remove the flame shot portion, the lands, and rechamber 1" shorter. Of course they are rechambering from the original reamer, so the chamber diameter is the same. Also the target barrels that they use are 28-30".

I don't know if this is practical in a shorter barrel, I have never heard of this being done. It just seems like it would be possible if not practical.

January 19, 2014, 07:04 AM
ok thanks
so would rechambering from a 270 to 30-06 be better id assume?

January 19, 2014, 08:02 AM
NO!! Rechambering has nothing to do with bore diameter. A .270 has a bore diameter about 0.030" smaller than a 30/06. Where do these ideas come from?

January 19, 2014, 11:05 AM
so would rechambering from a 270 to 30-06 be better id assume ?

You know what "assume" does, don't you ? . :p

Even if the .30-06 chambering reamer would totally clean up the .270 chamber (AFAIK, it won't), you would be in serious peril, should you attempt to drive a .308" boolit through a .277" bore.


Jim Watson
January 19, 2014, 11:18 AM
The problem is the decline of the English language.

"Rechambering" used to mean reaming the chamber so as to use a cartridge of a larger volume but the same caliber.
In the Internet Age it has come to mean any modification to another round. It can include rechambering, reboring, and rebarreling. With bolt and magazine modifications as required.

Read some of the above posts and other threads and see if that is not so.

And what was that about the difference between "clip" and "magazine?"

Bart B.
January 19, 2014, 11:46 AM
There's been a few folks who had their shot out barrel for cartridges smaller than a .30-06 (.257 Roberts in one instance I know of) rebored and rifled to 30 caliber then rechambered with a .30-06 reamer. While the accuracy such a barrel will have when all's done won't be quite as good as before, it's good enough for hunting larger game at shorter ranges.

Jim Watson
January 19, 2014, 12:03 PM
That used to be done a good deal, and goes way back.
I have a .38-55 that started out as a .32-40.

The rebored barrel may not have ended up on the same gun. I had an old article on the practice including "I may not have the only octagon barreled Mauser, but it is probably the only one barreled with Savage High Pressure Steel."

These days, reboring is expensive and slow. A new barrel does not cost much more and is usually more available.

January 19, 2014, 02:02 PM
guys first off im asking b/c I dont know so if I use wrong terminology I am sorry. If you can explain exactly what the right terms are that would be cool.

ill explain the situation so it makes more sense.
I had a winchester model in 30-06 years ago which i sold. I am looking to get the same kind back, which has proven to be a difficult task. I have found the same rifle in 270 and 300 win mag. My idea is to buy one and have it converted (for lack of a better term due to insufficent info) to a 30-06. So my question is which would be a better caliber to purchase?


James K
January 19, 2014, 02:31 PM
You can't rechamber a .300 Win Mag to .30-'06. You can drill a small hole bigger but can't drill a big hole smaller. And you can't rechamber a .270 to .30-'06; you will have to have the barrel drilled out and the rifling recut. You can re-barrel the .270 to .30-'06.

But .30-'06 Model 70's are so common that it would probably be less costly and a lot easier to just buy the gun you want and not sink money into converting anything.

A note on re-boring a barrel: The way folks talk on the internet about re-boring a barrel, it sounds like it involves a quick trip to a local gun store, or a DIY job with a Dremel tool and a rusty can opener. Not true.

Re-boring and re-rifling a barrel is a very specialized job, requiring costly equipment. It is done only by a few shops that specialize in the work, and they are usually heavily backlogged. The general gunsmith is not set up to do it; if you take the gun to your local gunsmith, he will only send it to one of those shops and meet the same delay. Nor is it always possible. The new caliber has to be big enough that drilling the barrel will remove all the old rifling Converting a .30 caliber to .375 is possible; converting .30 to .303 is a lot harder. And the outside diameter of the barrel has to be enough also. You can't bore a barrel to .50 if the outside diameter is only .48".


January 19, 2014, 03:16 PM
Of your choices, buying the .270 and having the barrel replaced with one chambered for 30-06 would be the best choice. (Of course it isn't going to be overly cheap, depending on what barrel you get I would assume at least $250 on the low end.) I assume the old 30-06 rifle you sold had some sort of sentimental value? Otherwise I would say the .270 Win anyway and just keep it a .270 Win. ??

January 19, 2014, 09:41 PM
Stalian, My 2 cents, buy the .270 and shoot it. If its a tack driver, keep it as is. If its nothing special, have it re-barreled to 06.

January 20, 2014, 02:11 AM
.270 is a great round. Buy yourself a new rifle and don't look back.

January 20, 2014, 09:30 AM
thanks a lot for the responses. Ill go ahead w the 270 and try it out

January 9, 2019, 10:37 AM
Been looking for a winchester or marlin straight stock lever action 30-30 for some time.I wanted one to be rebored by JES to 38-55.Today I cace across a winchester 307 in very good shape that the owner wanted to get rid of for a fantastic price.{HE hated the round ????} Can that caliber be rebored to 38-55?

January 9, 2019, 01:26 PM
Old thread, be better to start a new one.

The answer is technically yes, realistically no as its a lever action.

The problem is you have the dost of a barrel removed, install as well as the clambering

January 9, 2019, 09:04 PM
I will assume JES is a shop who advertises rebore/rerifle as a service offered.

Have you thought about contacting JES and asking him what sort of job he wants to take on,and what it might cost?

You also might check with an outfit like Numrich. Its possible they would have a used lever gun factory barrel in 38-55. You might also Check with Starline...I think they are making .375 Win brass . You might stumble across a lever .375 Win.

I once bought a rough bbl,blank,cut it tapered octagon,and fitted it to a Browning 92.

I also re-stocked it from a blank. A levergun rebarrel includes some forend cap work.I reworked a Win 86 part. You have to hang the mag tube Its not all that hard,but it takes more time than a bolt gun

I'm not a lever gun mechanic.I did not change cartridges.You might study case dimensions.Lever guns are more complex than bolt guns. Feeding from a tube mag requires parts working together with the cartridge. Mag tube and follower diameter,cartridge stops,lifters,bolt face,extractors come to mind.

Finding a 38-55 might be easier.Try a Collector Gun Show,ArmsList,etc….or have fun browsing old gun stores.You might ask the Gun Shop owner. Not all rifles are on display,maybe.

January 9, 2019, 09:57 PM
375win in Marlin & Win are not that hard to come by and JES can knock out a 38/55 out
of 336 or 94 Win very reasonable. 38/55 can be made from blowing out 30/30 brass. It comes up a little short but not enough to make a difference. I used blow out 30/30 brass for
375w but only at 38/55 load levels. The 38/55 & 30/30 are the same brass, the 375w uses a heavier case.

January 10, 2019, 01:15 AM
No you can't turn a .307 Win into a .38-55. The .38-55 chamber would never clean up a .307 Win chamber, you cold reborn to a .356 Winchester or possibly a wildcat .375-307. The .307 is similar in dimensions to a .308 Win cartridge, the .38-55 is basically a straight walled .30-30 case.

January 10, 2019, 01:18 AM
Reboring or rebarreling to 38-55 is not difficult, you need to come up with a few hard-to-find parts, but not impossible. Then you have to start loading your own ammo. Again, not impossible, just inconvenient for some people.

January 23, 2019, 01:45 PM
What is the rifle? How much are you willing to spend? Is there a reason why you want that particular rifle re-barreled? Sentimental value, want a easier shooting round, cost of ammo, accuracy?

I charge $300 to rebarrel not including the new barrel, assuming its not already chambered and threaded. Includes cleaning up the action, lapping the lugs, etc.. Different case head size and caliber has to be addressed per make/model. 700 no problem opening up the bolt or replacing. But add another $150+ to the cost for a new bolt. Savages just the bolt head can be changed. Tikkas may need a new bolt. Each situation will require its own research. Several things to take in to consideration. The cheapest option will almost always be to just buy another gun. But a good smith can take a average firearm and make it exceptional. I built a 6.5-284 out of a old .270, new barrel of course, and stock, and well everything but the action really. Turned a $250 gun into a $6000 gun. Also turned it from a 1.0 moa gun to a 1/4moa gun. With a range well over a 1000 yards.

January 23, 2019, 05:53 PM
Offroad….This SHOULD have been a new thread. Read post # 19 for the current topic.
Its about lever guns,30-30 or 307 to 38-55 conversion,etc.

January 25, 2019, 10:44 AM
I've only had one rifle re-barreled and, considering the cost and length of time it took, would never have a hunting rifle re-barreled. Trade it or sell it, and buy one with the chambering you want, preferably new, but consider used, provided you know a LOT about evaluating used guns. I sense from your previous question that you may not.