Rebarrelling my old 243 to another 308 based cartridge

[Jakethefake]

I have an old Brno 243 which is a nice rifle, but unfortunately the barrel is shagged. I have a new Howa in 243, so not much point in getting the same.
Initially I was planning to have it rebarrelled in 358 win, but I don't think I really have a use case for that.
Its a light weight sporter so I want to keep it that way. The plan is that will be used for pigs and hopefully deer, and carried on foot in the bush.
I don't really want to go to 308, as my Dad has an old tikka 308 I can used when need be, and I'll probably wind up with it eventually anyway.

So I'm thinking either 260 rem or 7mm-08. I reload so factory availability of ammo is not a major concern. I understand there is good availability of projectiles for both calibers.
I like the idea of the 260 as I already have an old 6.5 Swede that I really only use for plinking. Any 6.5 pills that don't work well in the 260 can be used for plinking ammo for the Swede.
On the other hand I wonder if the 260 has enough over the 243 to be worth it, so maybe 7-08 is the better choice.
Ultimately I'm guessing I wouldn't be unhappy with either of them, but maybe someone can swing me one way or the other?

Also, any thoughts on twist rate and barrel length would be great. Either way I'd like to keep the barrel as short as can be considered practical for the cartridge. And I figure I'll be running projectiles on the heavier side, probably bonded bullets, or nosler partitions.

[bladeracer]

I have an old Brno 243 which is a nice rifle, but unfortunately the barrel is shagged. I have a new Howa in 243, so not much point in getting the same.
Initially I was planning to have it rebarrelled in 358 win, but I don't think I really have a use case for that.
Its a light weight sporter so I want to keep it that way. The plan is that will be used for pigs and hopefully deer, and carried on foot in the bush.
I don't really want to go to 308, as my Dad has an old tikka 308 I can used when need be, and I'll probably wind up with it eventually anyway.

So I'm thinking either 260 rem or 7mm-08. I reload so factory availability of ammo is not a major concern. I understand there is good availability of projectiles for both calibers.
I like the idea of the 260 as I already have an old 6.5 Swede that I really only use for plinking. Any 6.5 pills that don't work well in the 260 can be used for plinking ammo for the Swede.
On the other hand I wonder if the 260 has enough over the 243 to be worth it, so maybe 7-08 is the better choice.
Ultimately I'm guessing I wouldn't be unhappy with either of them, but maybe someone can swing me one way or the other?

Also, any thoughts on twist rate and barrel length would be great. Either way I'd like to keep the barrel as short as can be considered practical for the cartridge. And I figure I'll be running projectiles on the heavier side, probably bonded bullets, or nosler partitions.

I would lean toward 7mm-08 and use Barnes TSX/TTSX or other copper bullets. You don't need as much mass as a jacketed lead bullet as the mono bullets tend to hold together better, which also lets you push them a bit harder. For pigs though I'd go with cheaper bullets like the Speer Hotcore 145gn and 160gn for the 7mm. If you ever decide to come down to Victoria to shoot some of our sambar, the 6.5's aren't legal here on the big deer species.

Your Swede should be shooting sub-minute already with handloads, but a modern rifle should be a fair bit lighter.

[northdude]

If your looking at 7mm and like the old school stuff would a 7x57 be worth a look?

[straightshooter]

Jakethefake
Your initial instinct will probably give you the most satisfaction.
Just how much advantage do you think a 6.5 or 7 mm will really have over a 6mm.
A 358 Win will be fairly happy with a 20" barrel and for fun there is always a wide range of pistol projectiles available and rifle projectiles if after serious game.

[Jakethefake]

If your looking at 7mm and like the old school stuff would a 7x57 be worth a look?

I had given some thought to that, but I assume 7mm-08 will be a much easier conversion from the 243. Will 7x57 fit in a short action?

[Jakethefake]

Jakethefake
Your initial instinct will probably give you the most satisfaction.
Just how much advantage do you think a 6.5 or 7 mm will really have over a 6mm.

Well, hopefully enough that its a worthwhile exercise.

A 358 Win will be fairly happy with a 20" barrel and for fun there is always a wide range of pistol projectiles available and rifle projectiles if after serious game.

Being able to use pistol projectiles was part of the reason I originally considered it. But I have a 1894 in 357 mag now, so it would be somewhat redundant in that regard. I certainly wouldn't discount having a 358 at some point in the future, in fact I'd really like a BLR in 358.
But for now I feel like I'd get more use out of something like the 7-08.

[bladeracer]

If your looking at 7mm and like the old school stuff would a 7x57 be worth a look?

I had given some thought to that, but I assume 7mm-08 will be a much easier conversion from the 243. Will 7x57 fit in a short action?

The 7x57mm is long action, same as the 6.5x55mm. You could chamber it but you'd be stuck with very short bullets to get a max length of the 2.800".

[bladeracer]

In the 7mm-08, 78gn SP bullets for small game, 175gn bullets for really big stuff, and a wide choice in between for everything else.

I'm hoping Hornady do their new CX bullets in 7mm soon.

Jakethefake
Your initial instinct will probably give you the most satisfaction.
Just how much advantage do you think a 6.5 or 7 mm will really have over a 6mm.

Well, hopefully enough that its a worthwhile exercise.

A 358 Win will be fairly happy with a 20" barrel and for fun there is always a wide range of pistol projectiles available and rifle projectiles if after serious game.

Being able to use pistol projectiles was part of the reason I originally considered it. But I have a 1894 in 357 mag now, so it would be somewhat redundant in that regard. I certainly wouldn't discount having a 358 at some point in the future, in fact I'd really like a BLR in 358.
But for now I feel like I'd get more use out of something like the 7-08.

[bigpete]

358w. Everything else is lame

[SCJ429]

What about 6 or 7mm BR Norma, or 6x47 Lapua or 6mm Creedmoor? To be different 7mm Creedmoor?

[SCJ429]

Or open up the bolt face and run 7mm WSM or 7mm RSAUM?

[deye243]

708 1 in 9 twist 22 inch if you use a 160g cup and core pill will drop anything up that way or use a 139 grain for the smaller stuff flatter shooting harder hitting than the 308 if there's any range and fantastic barrel life all that coming from a 260 owner

[wrenchman]

6.5x55 i was thinking of having a 243 swapped to i have a swede now that i got a great deal on

[6878mm]

Cannot go past any of the 6.5s 260rem,

[yoshie]

I re-barreled an old BRNO 243 to 260 Rem a few years ago now, I think is the most versatile calibre for Australia, biut since you already have a 243, 358 seems the next best option.

What about 358-284 Norma for a bit more punch?

[bigrich]

the one thing to be careful of , is COL . i have a tikka t3 in 7-08 and it's penalised with 2.8" mag length . it has so much more in it if i could seat 150gn projectiles out further for more powder room . so check the mag length of your brno first . if you've got 2.9" or more the 7-08 can be a real fire cracker

[SCJ429]

Cannot go past any of the 6.5s 260rem,

What can a 6.5mm case do that a 6mm case can't do better?

[GQshayne]

I reckon a 7mm/08 is a good option. Good all round cartridge for Oz.

[bladeracer]

I reckon a 7mm/08 is a good option. Good all round cartridge for Oz.

Agreed, it's hard to beat in most situations.

[Jakethefake]

Appreciate all the responses. At this point I'm pretty sold on 7mm-08. Going down south for sambar isn't something I'd considered, but now you've put the idea in my head bladeracer, I'd like to have the option.
I forgot to mention earlier, but I'm not particularly interested in magnum cartridges, and part of the reason I was only considering -08 based cartridges is because there is plenty of load data for 2208, which I have plenty of, and they only need standard large rifle primers, which I also have in stock, so I would only need brass and projectiles(and dies, of course), to get started, and if I can't find brass I can neck down some 308 brass. Although I would prefer to keep the head stamp correct if possible.

Plus it should be nothing more than a straight barrel swap for the old Brno. I think I'll have Allan Swan do it. I understand he's pretty busy these days, but the rifle has been waiting five or six years in the safe for this, another six months or so won't hurt.

[deye243]

Cannot go past any of the 6.5s 260rem,

What can a 6.5mm case do that a 6mm case can't do better?

On meat and bone ......... everything. It ain't always about paper

[deye243]

Appreciate all the responses. At this point I'm pretty sold on 7mm-08. Going down south for sambar isn't something I'd considered, but now you've put the idea in my head bladeracer, I'd like to have the option.
I forgot to mention earlier, but I'm not particularly interested in magnum cartridges, and part of the reason I was only considering -08 based cartridges is because there is plenty of load data for 2208, which I have plenty of, and they only need standard large rifle primers, which I also have in stock, so I would only need brass and projectiles(and dies, of course), to get started, and if I can't find brass I can neck down some 308 brass. Although I would prefer to keep the head stamp correct if possible.

Plus it should be nothing more than a straight barrel swap for the old Brno. I think I'll have Allan Swan do it. I understand he's pretty busy these days, but the rifle has been waiting five or six years in the safe for this, another six months or so won't hurt.

Just keep I mind that for pills over 140g 2209 is a better option for a number of reasons as in lower pressure and more velocity and a lower flame temperature something that adds greatly to throat and Barrel life

[SCJ429]

:friends:

Cannot go past any of the 6.5s 260rem,

What can a 6.5mm case do that a 6mm case can't do better?

On meat and bone ......... everything. It ain't always about paper

Using that thinking, why not 30 cal, surely it must be so much better on meat and bone.
A 6.5 is only a tiny step up from a 6mm, in most hunting situations it would make little difference.

[bladeracer]

:friends:

Cannot go past any of the 6.5s 260rem,

What can a 6.5mm case do that a 6mm case can't do better?

On meat and bone ......... everything. It ain't always about paper

Using that thinking, why not 30 cal, surely it must be so much better on meat and bone.
A 6.5 is only a tiny step up from a 6mm, in most hunting situations it would make little difference.

I think the difference between these two calibres is pretty wide actually. I consider the 6mm's more of a small-game calibre because it's limited to fairly light bullets - 50gn to about 105gn. The 6.5's though start at 85gn and go up to 160gn so I put them within the same realm as the 7mm's (generally 100gn to about 175gn). I think on medium game the difference between 80gn to 100gn bullets and 140gn to 160gn bullets can be fairly significant. On smaller game it probably isn't significant.

[bigpete]

Anything is better than a 6mm

[SCJ429]

[quote="SCJ429"


Using that thinking, why not 30 cal, surely it must be so much better on meat and bone.
A 6.5 is only a tiny step up from a 6mm, in most hunting situations it would make little difference.

I think the difference between these two calibres is pretty wide actually. I consider the 6mm's more of a small-game calibre because it's limited to fairly light bullets - 50gn to about 105gn. The 6.5's though start at 85gn and go up to 160gn so I put them within the same realm as the 7mm's (generally 100gn to about 175gn). I think on medium game the difference between 80gn to 100gn bullets and 140gn to 160gn bullets can be fairly significant. On smaller game it probably isn't significant.[/quote][/quote]
Not sure I understand your reasoning there Blade, that the difference between 6mm and 6.5mm is pretty wide but the difference between 6.5mm and 7mm is not? The difference is identical for each jump. What the smaller calibre misses out in projectile weight it has the advantage in speed and BC. This means less wind drift and more energy delivered onto the target.

[bladeracer]

Not sure I understand your reasoning there Blade, that the difference between 6mm and 6.5mm is pretty wide but the difference between 6.5mm and 7mm is not? The difference is identical for each jump. What the smaller calibre misses out in projectile weight it has the advantage in speed and BC. This means less wind drift and more energy delivered onto the target.

There is virtually no difference in bullet weight between the 6.5mm's and the 7mm's. Some 6's have a lot of velocity but so do some 6.5's and 7's.
The 6.5's and 7's generally have better longer-range ballistics than the 6's.

Taking three high-BC bullets in three common cartridges that make similar velocities, .243 with the 103gn ELDX, 6.5x55mm with the 147gn ELDM and the 7mm-08 with the 162gn ELDM all making 2650fps and zeroed at 200m (I also happen to own all of these rifles). All of these can certainly be tuned to make more velocity but I think these are reasonable loads to work with near the top end of load data in 22" barrels. And all of these offer different bullets that can swing the results significantly depending on purpose. An extra 100fps is not going to make a significant difference in their performance at longer ranges.

The .243 starts out making 2650fps and 1606ft-lb.
100m 70mm high
300m 270mm low
400m 775mm low
500m 1565mm low
600m 2680mm low
700m 4185mm low
800m 6175mm low
900m 8700mm low
1000m 11,870mm low 10mph wind 2950mm 318ft-lb 1180fps
So by 1000m it's making 1200fps, 320ft-lb of energy, is twelve meters low and drifting three metres on the wind.

The 6.5x55mm starts out making 2650fps 2293ft-lb.
100m 65mm high
300m 250mm low
400m 710mm low
500m 1405mm low
600m 2365mm low
700m 3615mm low
800m 5220mm low
900m 7200mm low
1000m 9625mm low 10mph wind 1955mm 698ft-lb 1460fps
By 1000m it's making 1450fps, 700ft-lb of energy, is 9.5m low and drifting two-metres on the wind - that is a very significant advantage. Even within the 500m hunting distances, although there is little difference in trajectory, the wind drift advantage is very significant, as is the energy.

The 7mm-08 starts out making 2650fps 2527ft-lb.
100m 70mm high
300m 250mm low
400m 710mm low
500m 1425mm low
600m 2400mm low
700m 3675mm low
800m 5320mm low
900m 7345mm low
1000m 9850mm low 10mph wind 2060mm 732ft-lb 1425fps
By 1000m it's making 1425fps, 730ft-lb of energy, is ten-metres low, and drifting two-metres on the wind.
If you can push the .6mm bullet at 3000fps you'll see similar trajectory to the 6.5mm and 7mm, but you still have 30% more wind drift due to the light bullet.

There really is little ballistic difference between the 6.5's and 7's as they shoot similar bullet weights with similar BC at similar velocities. The 6mm's have significant deficits across the board, which is why I view it as a small game calibre. By 500m it really starts dumping velocity. It's certainly capable of taking larger game, but it is not as capable as larger calibres firing heavier bullets.

[bigrich]

[quote="SCJ429"


Using that thinking, why not 30 cal, surely it must be so much better on meat and bone.
A 6.5 is only a tiny step up from a 6mm, in most hunting situations it would make little difference.

I think the difference between these two calibres is pretty wide actually. I consider the 6mm's more of a small-game calibre because it's limited to fairly light bullets - 50gn to about 105gn. The 6.5's though start at 85gn and go up to 160gn so I put them within the same realm as the 7mm's (generally 100gn to about 175gn). I think on medium game the difference between 80gn to 100gn bullets and 140gn to 160gn bullets can be fairly significant. On smaller game it probably isn't significant.

[/quote]
Not sure I understand your reasoning there Blade, that the difference between 6mm and 6.5mm is pretty wide but the difference between 6.5mm and 7mm is not? The difference is identical for each jump. What the smaller calibre misses out in projectile weight it has the advantage in speed and BC. This means less wind drift and more energy delivered onto the target.[/quote]

6.5 cal has a very good range of long high BC projectiles available .considerably better BC's than just about any other caliber . 6.5 also gives higher sectional density with it's long projectiles than other calibers for penetration . caliber width is not the only consideration

i've been using a 7-08 in the field, and 150 noslers at moderate velocity kill very well. i've also played with 358 win and it kills far better than paper statistics indicate . high velocity is good , but projectile choice for the job at hand becomes more critical .my 7-08 is extremely accurate , but mag length limits the ability to get the best out of this caliber in my tikka T3 . i'm getting 2625fps with 150 nosler BT's and accubonds , which sounds mild but had been devastating on reds and pigs with complete penetration . if i could load out further i could lift the fps considerably for flatter trajectory and more energy. from my research 260 rem and others can also be limited in case capacity with long BC projectiles taking up powder space in short mags as well.

my advice to the OP with regards to his project is to check his mag length BEFORE choosing a caliber and starting a build . i'm switching to 6.5x55 in a T3 as it uses a 30-06 length mag so i can load projectiles out . a lot of the older european and military calibers have generous free bore for the long round nose projectiles these originally came out in as well. my 9.3x62 is a good example ,(6.5x55 being another) being able to seat out has enabled me to go past listed load data to get excellent performance on large game .

[bladeracer]

Most people I find that love the .243 really like it for its velocity, but it gets those crazy velocities with the lighter bullets, which dump that velocity quickly.
A couple of examples to show this.

.243 58gn VMax 3925fps 1984ft-lb .250 200m zero (Hornady factory load).
100m 27mm high
300m 145mm low
400m 450mm low
500m 980mm low
600m 1800mm low
700m 3065mm low
800m 4950mm low
900m 7660mm low
1000m 11420mm low 10mph wind 5000mm 111ft-lb 930fps

The 87gn VMax is what I consider the most general purpose load you can use in the .243, it's hard to go wrong with it in almost any situation.
The .243 87gn VMax starts out making 3240fps and 2028ft-lb (Hornady factory load).
100m 42mm high
300m 180mm low
400m 540mm low
500m 1110mm low
600m 1940mm low
700m 3080mm low
800m 4635mm low
900m 6670mm low
1000m 9320mm low 10mph wind 3150mm 272ft-lb 1185fps
So by 1000m it's making 1200fps, 270ft-lb of energy, is 9.3m low and drifting three metres on the wind. It's trajectory is outstanding, but the wind drift is horrible, and wind is the biggest issue with long-range shooting, trajectory becomes largely irrelevant nowadays with our range-finding abilities.

Compare it with the 80gn ELDM in the .223 at just 2850fps.
100m 58mm high
300m 230mm low
400m 670mm low
500m 1360mm low
600m 2340mm low
700m 3655mm low
800m 5410mm low
900m 7650mm low
1000m 11520mm low 10mph wind 2900mm 264ft-lb 1220fps

The differences between the 87gn .243 and the 80gn .223 really are slight, and the .223 does it with significantly less powder. I run 23.5gn of AR2206H in the .223 and 36.5gn in the .243 for essentially the same performance.

[SCJ429]

But the 243 can shoot a 107 grain bullet in excess of 3000 fps and with a bit of coaxing at 3100 fps. This is about the same speed a 260 can produce with the same weight of bullet but worse BC. Hitting a goat at 500 metres with either projectile would be quiet similar but the 243 has the edge. It is like comparing the 7mm08 to the 308, they are very similar but the 7mm has the edge.