6mm Remington Conversion

[Deputy819]

Got a question for a Gunsmith about whether or not it's possible to convert a 6mm Remington into a .243 Winchester without setting the barrel back. Considering that the 6mm Remy is a necked down .257 Roberts and a .243 is a necked down .308 can the chamber just be "cleaned up" with the .243 reamer or will there be "shoulder issues" requiring barrel set-back? Thanks a bunch!

 

[Jerry M]

No gunsmith here but a 6 mm Remington is longer than a .243 Winchester, so to answer your question No, the barrel would have to be set back.

 

[Deputy819]

No gunsmith here but a 6 mm Remington is longer than a .243 Winchester, so to answer your question No, the barrel would have to be set back.

Gotcha! Thank you, sir! My Smith is doing a complete overhaul on a rifle that I never could get to shoot consistently and he said he'd check his "books" on the specs regarding the rechambering and get back with me. I knew I could probably get an answer here sooner.

 

[therifleman556]

If you can't get it to shoot as a 243, what guarantees it will perform as a 6mm? Personally, if I'm spending money for work done I'd be putting a new barrel on first.
It may work as intended, but you could also be paying to have a questionable barrel converted to a caliber that requires different dies and brass that still might not shoot well.
I myself would love one of the high stepping 6mms, but it looks like you might be shelling out some coin for little assurances.

 

[Rick Richard]

If it were me, I would replace the barrel with a good custom barrel and true th action. That would highly increase the chances of getting it to shoot up to your expectations. Just my experience and may be cheaper in the long run.

 

[Capt RB]

Gotcha! Thank you, sir! My Smith is doing a complete overhaul on a rifle that I never could get to shoot consistently and he said he'd check his "books" on the specs regarding the rechambering and get back with me. I knew I could probably get an answer here sooner.

Get a new smith!! He's an idiot if he cannot give that answer immediately!!!!

 

[shortgrass]

Get a new smith!! He's an idiot if he cannot give that answer immediately!!!!

Gotta' agree with that ^^^^^^ 100%. Accuracy is in the barrel, not the cartridge it is chambered for,,, until you get down to the PPC's and Br's. If your rifle won't shoot consistently just a re-chamber isn't gonna' help.

 

[Deputy819]

If you can't get it to shoot as a 243, what guarantees it will perform as a 6mm? Personally, if I'm spending money for work done I'd be putting a new barrel on first.
It may work as intended, but you could also be paying to have a questionable barrel converted to a caliber that requires different dies and brass that still might not shoot well.
I myself would love one of the high stepping 6mms, but it looks like you might be shelling out some coin for little assurances.

Thanks for the responses, gentleman. It's going FROM a 6mm Remy TO a .243 Winchester. Action has already been trued and the barrel is a Douglas XX match grade barrel. I just never could get consistent groups out of it no matter what components I tried OR what new "tools/toys" I added to my reloading bench. There aren't any guarantees it will perform better as a .243. Gonna put it in a new H.S. Precision Stock (it was previously in a Choate) and the Leupold scope that was on it has been sent back to Beaverton just to make sure that wasn't the problem. The Smith that did the original build quoted me @ $300.00 to re-chamber to a .243 and open up/skim bed the new stock. If none of this proves effective then that rifle will be parted out and sold off and I guess I'll just buy a Ruger Precision Rifle and forget the whole "custom build" scene.

 

[Deputy819]

Get a new smith!! He's an idiot if he cannot give that answer immediately!!!!

I kinda thought that was a little odd myself. The length difference didnt occur to me until it was mentioned. Duh! I was more hung up on shoulder differences between the two cartridges.

 

[therifleman556]

Shows how well I comprehend what I'm reading. Sorry folks, guess I have to change my posting permissions to "only after 2 cups coffee"

 

[Deputy819]

Nah, you're fine. I appreciate the feedback!

 

[LoneTraveler]

The 6mm Rem. and 243 Win is a pair of Bastard Children when converting from one chamber to the other. The 243 W. case length 2.045, 6MM Rem. 2.233. The 243W Body Shoulder is .454, The 6MM Rem.is .429. If you go 6MM Rem to 243W the barrel will have to be set back for the shorter case. If you go from 243 W to 6MM Rem. The barrel would have to set back so the larger body to shoulder diameter will be cleaned up in the new chamber.

If the rifle did not shoot to expectation as a 6MM rem. With the cost of cutting and threading a setback job, and cutting new chamber. You may want to consider a new barrel and a chance to get the better accuracy you are looking for in this rifle.
Good Luck on this adventure.

 

[Deputy819]

The 6mm Rem. and 243 Win is a pair of Bastard Children when converting from one chamber to the other. The 243 W. case length 2.045, 6MM Rem. 2.233. The 243W Body Shoulder is .454, The 6MM Rem.is .429. If you go 6MM Rem to 243W the barrel will have to be set back for the shorter case. If you go from 243 W to 6MM Rem. The barrel would have to set back so the larger body to shoulder diameter will be cleaned up in the new chamber.

If the rifle did not shoot to expectation as a 6MM rem. With the cost of cutting and threading a setback job, and cutting new chamber. You may want to consider a new barrel and a chance to get the better accuracy you are looking for in this rifle.
Good Luck on this adventure.

Thank you, sir. Will strongly consider your suggestion.

 

[johnnyk]

I have read/heard of certain rifles being re-chambered (from 7mmRemMag to 7mm STW) that actually shot better after the chambering job was complete. It is possible that the original chamber (6mm) is not concentric (share the same center) with the bore.
You could also consider the 6mm AI, 6-284 Norma or even the .243AI. All are high stepping 6mm's and would be better than the standard .243Win, as far as case stretch goes. Good luck and let us know what happens. Interested to see if a chamber job helps. johnnyk.