Is my 6mm rifle capable of shooting 243?

S

shmitty

New member
My deer rifle as a kid was a 243....I thought. I had let a family member borrow it for several years (like 20) and recently got it back. Funny thing is, it's stamped 6mm REM on the barrel and model is Remington Mohawk - 600. I have ammo still from shooting it a long time ago and it's all 243.

So, is this the same rifle? And a better question, can I shoot 243 through it since I cannot find 6mm anywhere.

I just joined this forum and tried to search for this answer, so thanks in advance if you can help

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6mm Remington and .243 Winchester are two distinct rounds and are not considered interchangeable even though they do shoot bullets with the same diameter.

The 6mm Remington is based on a necked down .257Roberts while the .243 Winchester is based on a necked down .308.

The 6mm Remington is the longer of the two cartridges and runs at a slightly higher pressure. I was able to find some evidence that .243 Winchester will chamber and fire in at least some 6mm Remington rifles. Even so, it's not a recommended practice.
 
No, you cannot shoot .243 in a 6mm. While the bullets are the same diameter, the brass is not the same size.

The .243 is based on the .308 case while the 6mm is essentially made by necking down the .257 Roberts (which is an altered 7x57).

What this means is that the case shapes are not the same.

You should be able to find 6mm ammunition through sources like Midway USA, Midsouth Shooter's Supply, or Natchez Shooters Supplies.
 
Any chance you wrote down (and still have) the ser# of the one you used as a kid?

I've never seen a Mohawk in anything but .243. I have one. Also have Model 600s (not Mohawk 600) in .222, 6mm, .308, & .350Rem Mag.

Any chance that old ammo (.243) has some fired cases??

The 6mm case is 0.078" longer from the base to the base of the neck than the .243 is. .243 cases fired in a 6mm chamber will have the shoulder blown forward that amount, which would be obvious if compared to an unfired case, or one fired in the correct chamber.

The .243 case is also spec'd 0.024" greater diameter at the shoulder than the 6mm case, which might make it a crush fit in a 6mm chamber, depending on individual case and rifle tolerances.

As I see it, the possible options are (in no particular order)..
#1) you mis-remembered the caliber of the gun
#2) its a different gun, same make, & model, but in a different caliber...
(perhaps something happened to it, and your relative replaced it with the closest thing he could find?)

#3) its the same gun, but rebarreled from .243 to 6mm...
(same as #2, but relative shot out the barrel, and could only get a 6mm barrel to replace it with... if either one of these, you need to talk to that relative, :D)

I have no idea what actually happened, just naming possibilities....

#4) it is the same gun, a rare factory mismark and you never realized it as a kid...
#5) You are misidentifying a Model 600 as a Mohawk 600


One thing I do know is that you SHOULD NOT shoot .243 ammo in a 6mm chamber, (even if it does work). I don't know from personal experience if it will chamber or not.

If it were life and death, I'd say try it. It's not. 6mm Rem ammo and brass aren't common, but they are out there, still. If you handload, brass can be formed from several other cases, 7x57 Mauser was the parent case for the 6mm (.244 Rem).

I will tell you this from personal experience, if you have a case rupture in a Rem 600, some gas WILL hit you in the face.

If at all possible, some clear pictures of your rifle would be nice. The 600 series rifles went through several variations, with the Mohawk being the last ones catalogued.

Hope this helps. DON'T SHOOT .243 in a 6mm gun!

Take it to a gunsmith and have the chamber checked, that at least will settle if the barrel is properly marked, or not...

Good Luck, let us know more, when you can.
 
Okay thanks. I found some 6mm ammo online... I must have shot 243 rounds through this gun previously. Is that possible?

I will only use 6mm in the rifle now

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I have always thought that the 6mm Remington is a slightly better cartridge than the 243 for those who reload. If you don't reload, the 243 is a far better choice. If you are comitted to the rifle, it's an excellent excuse to take up reloading.
 
Okay thanks. I found some 6mm ammo online... I must have shot 243 rounds through this gun previously. Is that possible?
Click to expand...

Yes it is possible. Plenty of 308 has been fired out of 30-06 chambers by mistake, and other than accuracy being poor the Garands were no worse for wear.

But it is not safe.

Jimro
 
Could it be that you were shooting .244 Remington back then which is what the 6mm started out as and the .243 was a mistake?
 
I'm not sure you could chamber .243 cartridges in a 6mm Remington easily. The 6mm Remington has more taper to the case than the .243 Win. The 6mm tapers from a base diameter of .470" to a shoulder diameter of .429" and the .243 Win has the same base diameter but a shoulder diameter of .454". The shoulder on the 6mm Rem is 0.164" farther forward than the .243 Win though, so it might chamber but I imagine it would take some effort to do it.
 
"...must have shot 243 rounds through this gun..." Not likely. Like taylorce1 says, a .243 won't fit in a 6mm chamber. You won't be able to "chamber size"(a 100% self-invented term) 25 thou and 6 degrees of taper.
http://stevespages.com/jpg/cd6remington.jpg
http://stevespages.com/jpg/cd243winchester.jpg
"...marginally superior..." Tryin' ter start a fight, eh? Difference is similar to the .30-06 and .308 velocity wise. About 100 fps with like bullet weights. Biggest difference is that you can find .243 ammo/brass anywhere. 6mm Rem not so much.
 
Could it be that you were shooting .244 Remington back then which is what the 6mm started out as and the .243 was a mistake?
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Wondering if this is the case. "When I was a kid", how long ago was that? 6mm Remington and .244 Remington are the same round, it was just reintroduced with a different twist rate in the rifles.

Could it have been .244, and you are remembering .243?
 
"...marginally superior..." Tryin' ter start a fight, eh? Difference is similar to the .30-06 and .308 velocity wise. About 100 fps with like bullet weights. Biggest difference is that you can find .243 ammo/brass anywhere. 6mm Rem not so much
Click to expand...

The 6mm give a little better ballistics because the neck is longer and the taper is not as severe as the .243. You can seat longer, heavier bullets easier in the 6mm.

The real advantage for a person that reloads is the neck being longer makes it easier to neck resize the 6mm.

Have had a 6mm Ruger #1 since 1980 and have found I could neck resize the brass five times before it had to be fully resized and then trimmed.

Used to regularly shoot with a friend that use a .243. In the field, there really wasn't any difference between the rounds.
 
Shooting .244 through it makes sense, I believe that they used the same case, just altered the ballistics a bit and althered the twist rate.

Could a 6mm and a .243 share the same bolt? I don't think that the shell holders are interchangeable.

In any case, I am afraid that the difference in case dimensions could make that a dangerous plan. I'm not exactly sure, but as said, the taper is wrong, the head may be wrong, the shoulder may be off, it would take a little looking to be sure, but I think that if it didn't fireform properly, it could cause a gas leak or even dangerous rupture.

My brother had a 6mm, I had a .243, I congratulated him on picking the one that he couldn't find ammo for. He never shot it much and resold it soon.
 
briandg said:
Could a 6mm and a .243 share the same bolt? I don't think that the shell holders are interchangeable.
Click to expand...

Yes both the 6mm Rem and .243 both use the same bolt face size. They just don't share the same sized shell holder because the rim thickness is different.
 
I had to make a few phone calls today just to make sure I was correct. A old neighbor of ours used to hunt with a reminton 742 chambered for 6mm. When he couldn't get shells for it he would buy the 243. He didn't like doing it because they didn't eject very reliably but he did do it. I had to call his son to verify. He said when his dad passed all he had was a box of 243 and no 6mm. He did not own a 243 chambered rifle.
 
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