6mmRem to a 243Win.

I'm not sure if I am over or under thinking this. Maybe I will sit back and see if it clears up.

No, you can't. Why not? Same reason you can't shoot 22-250 loads in a 223 case. They share a caliber, but that's it. The question actually doesn't make much sense.

If you want to keep the 6mm velocity, keep the 6mm. It sounds like you're planning on hand loading anyway, so it shouldn't be an issue. I'm building a 6mm Rem on an 1909 Argy receiver. I like the longer neck on the 6mm as compared to the 243, but they're both good.

Matt

The 6mm is better anyhow, unless you depend on buying ammo at Cheapmart.

I personally wouldn't rebarrel or rechamber a 6M/M Rem to a 243. For the most part I would consider that a step backward. The only advantage I think would be the availability of brass.
The 6M/M is similar to the 244 Rem. The 244 rem has a slower twist rate than the 6M/M and the 243 and could only stabilize light bullets.
The 243 was introduced to compete with the 244 and gained popularity because the 243 would shoot heavier bullets for hunting big game. Remington then come out with the 6M/M, but was to late to gain much popularity, even though it was a superior cartridge.

Why would you rebarrel to 243???

And why would you not want to use the 243 loads...since the brass/case is different?

And again, if you already have a 6mm, why rebarrel to 243?

This reminds me of the book Catch 22. The only reason to rebarrel the 6mm is to go up to 7x57 or 257 Roberts....or to rebarrel to another 6mm with a bit faster twist to handle 100 grain bullets better.

If you did happen to buy a 6mm with a slow twist (as toiville2feathers is referring to) I would rebarrel it, but it would stay 6mm, but with a 1:9 or 1:10 twist.

Matt

Do you mean can you use 6mm loading data after you rebarrel to .243? The answer to that would be no. Smaller case=higher pressures.

Seriously, 6mm is the superior cartridge. If you buy it, leave it alone. Still plenty of ammo for it.

Most wouldn't advise you to do so in the first place. Leave the 6mm barrel.

Short answer is no. It isn't advisable to shoot ammunition down the barrel that is meant for a different caliber...... ever.

You can buy an already-a-243 for the less money you can buy a 6mm and re-barrel to some other caliber.

The 6mm is a superior round. Keep it.

...or to rebarrel to another 6mm with a bit faster twist to handle 100 grain bullets better.

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I know a guy who did exactly this. The gun was scary accurate before, when I shot it. He's noting improved accuracy and performance.

Seriously, if you're hand loading, go with the 6mm. The .243 is a decent substitute if you're only buying off the shelf ammo.

There's nothing wrong with the .243! But, there's nothing wrong with the 6mm, either. The .243 has the market share. If I'd gotten a 6mm instead of my .243, I wouldn't be thinking about re-barreling it. I'd be looking for brass!

Samclrk said:

OK...If I buy a 6mm Rem.rifle and then rebarrel it to a 243..Can I shoot loads from the 6mm charts..And exactly why not..?

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Huh???

6mm and 243 are the same bore diameter. Why would you replace the barrel with one of the same size? The chambers are different. The 6mm Rem has a higher case capacity, exactly 1 grain in terms of powder charge.

The 6mm Rem will push a 107 grain pill about 50 fps faster than a 243 Win. Both are excellent cartridges and can be made to shoot as accurately as you want to spend. Obviously the 243 Win being the most popular and having the greatest availability of components.

I built a 243 Ackley Improved. It pushes the 107 bullet at 3200 fps with a conservative load and 3300 fps with a hot load (26" barrel). But you can also wildcat the 6mm Rem to and AI version an outdo the 243AI slightly. The ballistics on this bullet are outstanding.

You can expect to re-barrel all the fast 6mm's after about 1000 rounds. Performance has its price.

I do love my 243AI. I'm on the second barrel.



Fire formed 243AI case

Samclrk said:

OK...If I buy a 6mm Rem.rifle and then rebarrel it to a 243..Can I shoot loads from the 6mm charts..And exactly why not..?

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NO, because it will not fit !....................Yes You Can !...................

Samclrk said:

Thanks..I might consider the 243AI.,,I`m wanting the 243 ,but I`m asking if it`s safe to shoot the 6mm Rem. loading charts of the 6mm Rem.in a 243 chamber.Everybody is saying no..Thanks,everybody for commenting.

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Many of the 6mm loads wouldn't even fit in a .243 case, as the 6mm case is BIGGER! (longer)

A bigger case alows more powder to be used at the same pressure of the .243, and that = a higher velocity.

Have you even taken the time to compare the 6mm cartridge case "side by side" to the .243 to see the difference???

DM

Why not fire form your brass? You can get a book on how to fire form brass to make the 6MM. Good Luck.

AABEN said:

Why not fire form your brass? You can get a book on how to fire form brass to make the 6MM. Good Luck.

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NOT out of .243 brass you can't!

DM

Samclrk said:

Thanks..I might consider the 243AI.,,I`m wanting the 243 ,but I`m asking if it`s safe to shoot the 6mm Rem. loading charts of the 6mm Rem.in a 243 chamber.Everybody is saying no..Thanks,everybody for commenting.

Click to expand...

OK, I understand the question but why would you want to? Are you saying that you want to fire form 6mm Rem brass from 243 Win? I don't know if you can or not. But, if you can get 6mm Rem brass, that would be your best option.

There is really not enough difference between the two cartridges to sweat over. Certainly not enough to make you want to go through the painstaking process of fire-forming brass unless you already have the 6mm Rem and just cant get brass.

You certainly can't go wrong with a 243. It is an excellent cartridge. My Ackley was so accurate that I hunted with the fire-form loads until they were all shot up. I took a nice white tail in Kansas with it two years ago (243 loads). Get a barrel (any 6mm/243 for hunting big game) with a 1:8 twist. This will let you stabilize big bullets with high BC's. You can easily push the 105's at 2900 fps.