6mmRem to a 243Win.


PDA






Samclrk
August 25, 2013, 01:53 PM
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..?

If you enjoyed reading about "6mmRem to a 243Win." here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
squarepants33889
August 25, 2013, 02:00 PM
I'm not sure if I am over or under thinking this. Maybe I will sit back and see if it clears up.

morcey2
August 25, 2013, 02:12 PM
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

Jim Watson
August 25, 2013, 02:14 PM
The 6mm is better anyhow, unless you depend on buying ammo at Cheapmart.

toiville2feathers
August 25, 2013, 02:46 PM
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.

Abel
August 25, 2013, 02:49 PM
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.

morcey2
August 25, 2013, 02:49 PM
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

Samclrk
August 25, 2013, 02:53 PM
Thanks for the replies.

ETXhiker
August 25, 2013, 02:54 PM
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.

Samclrk
August 25, 2013, 03:14 PM
ET,yes.That was my question..Thank you

gunownerz
August 26, 2013, 06:22 PM
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.

W.E.G.
August 26, 2013, 06:31 PM
You can buy an already-a-243 for the less money you can buy a 6mm and re-barrel to some other caliber.

planetmobius
August 26, 2013, 08:16 PM
The 6mm is a superior round. Keep it.

Outlaw Man
August 27, 2013, 11:16 AM
...or to rebarrel to another 6mm with a bit faster twist to handle 100 grain bullets better.
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.

sixgunner455
August 27, 2013, 11:34 PM
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! :D

Samclrk
August 27, 2013, 11:42 PM
I realize the 6mm is more powerful.but is it as accurate?Or more so?..I only shoot at paper.

Woolecox
August 28, 2013, 12:04 AM
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..?
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.

http://i714.photobucket.com/albums/ww142/woolecox/243%20Ackley/PlanoCase2.jpg

Fire formed 243AI case

http://i714.photobucket.com/albums/ww142/woolecox/243%20Ackley/243CartComp.jpg

303tom
August 28, 2013, 12:23 AM
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..?
NO, because it will not fit !....................Yes You Can !...................

Samclrk
August 28, 2013, 11:59 PM
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.

Samclrk
August 29, 2013, 12:08 AM
Thanks,Mr.Woolecox..Nice looking rifle.

DM~
August 29, 2013, 03:26 PM
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.

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

AABEN
August 29, 2013, 03:34 PM
Why not fire form your brass? You can get a book on how to fire form brass to make the 6MM. Good Luck.

DM~
August 29, 2013, 04:56 PM
Why not fire form your brass? You can get a book on how to fire form brass to make the 6MM. Good Luck.

NOT out of .243 brass you can't!

DM

Woolecox
August 29, 2013, 10:51 PM
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.
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.

Samclrk
August 29, 2013, 11:37 PM
Just axeing a question...The 243 case will hold any load that is listed in the reloading charts for the 6mm data loading charts.I shoot 81 grains of powder in my 243 every day..The actions ARE the same.But like people are saying,the 6mmRem chamber is bigger, it will have lower pressure..That is what puzzles me ...But I guess it`s true.No arguement there..Just like a 30-06 has a lower chamber pressure than a .308

243winxb
August 29, 2013, 11:52 PM
Cant use the 6mm data in 243.

morcey2
August 29, 2013, 11:59 PM
Just axeing a question...The 243 case will hold any load that is listed in the reloading charts for the 6mm data loading charts.I shoot 81 grains of powder in my 243 every day..The actions ARE the same.But like people are saying,the 6mmRem chamber is bigger, it will have lower pressure..That is what puzzles me ...But I guess it`s true.No arguement there..Just like a 30-06 has a lower chamber pressure than a .308

:eek:
You can't fit 81 grains of powder in a 243 case. Ever. Period. You can't fit 81 grains of powder in 30-06 case.

The 6mm chamber is bigger because the 6mm cartridge case is bigger. The 6mm actually operates at a higher pressure than the 243 according to SAAMI. 65kpsi v. 60kpsi respectively. Most reloading data has them both at about 60kpsi.

There isn't a huge difference in performance between the two, but you can't fit the max load from most 6mm load data into a 243 case without going over the case capacity. You have a fundamental misunderstanding of case size, chamber size, and the physics of fitting 10 lbs in a 5 lb bag.

Matt

Samclrk
August 30, 2013, 12:06 AM
Sorry,morcey2..I meant to say 51 grains..Not 81..Sorry.

morcey2
August 30, 2013, 12:17 AM
Sorry,morcey2..I meant to say 51 grains..Not 81..Sorry.
Regardless, which powder is it? There are a few powders that will go to the 51 grain area in 243, but those same powders load in the 54 grain max range in 6mm. Superform is one of them. Because of the similarity in case size, there will be significant overlap in the load data, but it's a really good bet to say that every 6mm Max load will be severe overpressure loads if crammed into a 243 case.

Which powder are you using for the 51 grain loads?

Matt

Samclrk
August 30, 2013, 12:22 AM
Win780..I also use the Mag. primers

morcey2
August 30, 2013, 12:32 AM
Win780..I also use the Mag. primers
That's almost 2 grains above the max load I can find anywhere for any weight bullet for the 6mm with a standard primer. It's over 3 grains above the max for 243, again with any bullet I can find and a standard primer.

I think you've blown way past pushing the limits and right into flat-out dangerous territory.

Matt

303tom
August 30, 2013, 12:48 AM
Cant use the 6mm data in 243.
Yes you can..............
.243 Winchester.
100 GR. SPR BTSP Hodgdon H1000 .243" 2.650" 44.0 2876 45,700 CUP 47.0C 3000 49,800 CUP
6mm Rem.
100 GR. SPR BT Hodgdon H1000 .243" 2.775" 47.0 2779 41,500 PSI 50.0C 2955 48,900 PSI
Right out of the book................

Samclrk
August 30, 2013, 12:51 AM
I use a Lyman`s book ``Lyman Reloading Handbook,46th Edition``,,70grain bullet-Win785 52grains....I`ve been using this since 1963..The 6mmRem.=52grains Win 785.

viking499
August 30, 2013, 12:54 AM
81 grains?

Oops, now I see the correction.

Samclrk
August 30, 2013, 01:17 AM
LOL....Yeah,it`s late.....Sorry about that..

Bexar
August 30, 2013, 01:18 AM
I wouldn't...Sort of like trying to get .357 mag velocities out of a 38 Special case. You might be able to stuff a .38 case with enough powder but the pressure curve is going to hit quicker because of the reduced .38 Special case volume. Same effect with the .243/6mm scenario...case volume is part of the safety equation along with pressure. You might get away with it in the ,243 if you use an extremely slow burning powder but that's not my advice or recommendation. I've got a 6mm Remington case on my keyboard right now and I occasionally enjoy picking it up and rolling it between my fingers. But I digress...since you're only shooting paper and the question of terminal velocity and bullet selection is moot...do whatever brings you the most enjoyment.

Samclrk
August 30, 2013, 01:30 AM
Thanks,Bexar...I agree.

MachIVshooter
August 30, 2013, 01:54 AM
I realize the 6mm is more powerful.but is it as accurate?Or more so?..I only shoot at paper.

Accuracy is not a function of the cartridge. Platform, barrel, load & shooter determine accuracy. Some cartridges are referred to as being "inherently accurate", but that's a misconception; some cartridges are simply less finicky when it comes to variation in load. Namely, shorter cartridges tend to get more uniform burning of the powder column with a wider range of powder types and load density.

Kind of a moot point, though, as achieving best accuracy with ANY round in ANY rifle requires fastidious load development.

As for rechambering a 6mm to .243, I think that one's been drilled home pretty well, but I'll just point out one other reason to NOT do it:

In addition to greater case capacity, the 6mm also has a longer case neck and is used in mid-length or long actions; this gives you greater flexibility with bullet weights and profiles.

Also, there has been some mention of the slow twist rate. Just to clear that up, the rifles in question have a 1:12 twist, and the barrel will be labeled ".244 Rem", which is a cartridge that has the exact same physical dimensions as the 6mm. But production rifles with barrels marked "6mm Rem" have a 1 in 9" twist. I believe the change occurred around 1967, and the only reason for the renaming was the change in twist rate of the rifles; Remington was losing sales to the .243 because the slow twist in .244 rifles didn't stabilize > 90 gr. bullets well, so the .244 was relegated to use on varmints and small deer or pronghorn. The name was changed as a marketing strategy only; there is no difference in the cartridge itself.

Samclrk
August 30, 2013, 02:00 AM
Thanks,mach...

243winxb
August 30, 2013, 10:25 AM
Yes you can..............
.243 Winchester.
100 GR. SPR BTSP Hodgdon H1000 .243" 2.650" 44.0 2876 45,700 CUP 47.0C 3000 49,800 CUP
6mm Rem.
100 GR. SPR BT Hodgdon H1000 .243" 2.775" 47.0 2779 41,500 PSI 50.0C 2955 48,900 PSI
Right out of the book................ Put that 50.0 gr. Compressed, in the 243 for me. Photos please. :D

303tom
August 30, 2013, 01:18 PM
Put that 50.0 gr. Compressed, in the 243 for me. Photos please. :D
Thats just being ridiculous, I`m just saying you can use 47 grs. of H1000 in the 6mm Rem. & the .243 Win. safely.............

HOOfan_1
August 30, 2013, 02:32 PM
Thats just being ridiculous, I`m just saying you can use 47 grs. of H1000 in the 6mm Rem. & the .243 Win. safely.............

I am pretty sure the OP was asking if he can use the reloading data for the 6mm Remington with the .243. Considering the 6mm starts out with a higher minimum and ends up with a higher maximum, the answer is NO!!!

Do they have loads that overlap? Yes...but why would the OP look at the loading data for the 6mm Remington in order to find an overlapping load for a .243?

USE THE LOADING DATA FOR THE CARTRIDGE YOU INTEND TO SHOOT!!!

Why would we confuse the OP by saying anything else?

DM~
August 30, 2013, 04:51 PM
i am pretty sure the op was asking if he can use the reloading data for the 6mm remington with the .243. Considering the 6mm starts out with a higher minimum and ends up with a higher maximum, the answer is no!!!

Do they have loads that overlap? Yes...but why would the op look at the loading data for the 6mm remington in order to find an overlapping load for a .243?

use the loading data for the cartridge you intend to shoot!!!

why would we confuse the op by saying anything else?

+1

dm

morcey2
August 30, 2013, 06:06 PM
I'm still trying to figure out if it's 51 grains of 780 or of 785. Either one isn't coming anywhere near a rifle of mine, be it 243 or 6mm. Both are too slow to work anywhere near optimally for a 70 grain pill. Something in the Varget/4064 thru 4350 range would work much better.


I use a Lyman`s book ``Lyman Reloading Handbook,46th Edition``,,70grain bullet-Win785 52grains....I`ve been using this since 1963..The 6mmRem.=52grains Win 785.

There's a reason that they came out with 47, 48, and 49th editions since then. As pressure measurement technologies improved, many of the existing loads were determined to be way too hot. I don't know how 780 and 785 relate in terms of performance, but I'm pretty sure that they're not equivalent. Lyman 49 doesn't even list 780 on the 70 grn laods The slowest on in there is H4831 @ 50.5 grns.

If you've been shooting the same load for 50 years, why are you asking? I'm going to make an assumption that your current 6mm barrel is shot out, which tends to happen when you're shooting a lot over 50 years, and you want to rebarrel it. 243 sounds enticing, but you want to keep the velocity you get from the 6mm. You've also run out of 785 since they quit making it at some point in the last decade (I think) and you need a new load.

If that's the case, rebarrel it to the 6mm and work up loads using the existing 6mm data. If you rebarrel it to 243, work it up with the 243 data. The newer data is significantly more accurate in terms of pressure and are much better in terms of barrel life and keeping all of your eyes, ears, and fingers intact.

Matt

303tom
August 31, 2013, 12:41 AM
I am pretty sure the OP was asking if he can use the reloading data for the 6mm Remington with the .243. Considering the 6mm starts out with a higher minimum and ends up with a higher maximum, the answer is NO!!!

Do they have loads that overlap? Yes...but why would the OP look at the loading data for the 6mm Remington in order to find an overlapping load for a .243?

USE THE LOADING DATA FOR THE CARTRIDGE YOU INTEND TO SHOOT!!!

Why would we confuse the OP by saying anything else?
Why would the OP be reloading without a Reloading Handbook ?.................This right here is the reason I don`t usually answer reloading questions, and I am done with this one !..............

DM~
August 31, 2013, 02:20 PM
Why would the OP be reloading without a Reloading Handbook ?.................This right here is the reason I don`t usually answer reloading questions, and I am done with this one !..............

I agree, it's ALSO the reason i rarely give out load data on the net too.

Anyone that's going to reload, should NOT be too cheeeeeep to buy the loading manual for the brand bullet they choose to use!!

DM

If you enjoyed reading about "6mmRem to a 243Win." here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!