6mm Creedmoor vs. .243

[dahermit]

I am a traditionalist who looks with a jaundiced eye to everything "new" and "better" but am willing to be swayed by convincing evidence.

Therefore, inasmuch as the 6mm Creedmoor is based on a .308 case albeit shorter and with a sharper shoulder, what is the advantage of the 6mm Creedmoor over a standard .243 Winchester, whether standard or with an improved shoulder?

[ruger357w]

The 6mm creedmoor has a faster twist rate barrel for heavier bullets

[mikejonestkd]

The creedmoor launches same weight bullets about 100 fps faster than the 243 win.

[dahermit]

Originally Posted by mikejonestkd

The creedmoor launches same weight bullets about 100 fps faster than the 243 win.

So, what has it got over the 6MM Remington?

[Colorado Redneck]

150 fps. Creedmoor has an 8 twist, and is spec'ed at higher pressure.

[kilotanker22]

The 6mm creedmoor case was based on the 6.5 creedmoor case. Which was based on the 30 TC case. The 243 is based on the 308 case.

The advantage of the creedmoor cartridges over their 308 based counterparts is this. Having a shorter case allows you to seat the bullets further out of the case and still fit into a standard magazine. Eliminating some of the space that the long bullets protruding into the case of the 308 based counterparts. Increasing Available space for powder in one way.

The sharper shoulder and straighter contour of the case walls allows increased powder capacity in the shorter case. Also the 6mm creedmoor will have a tighter twist rate to stabilize those heavy for caliber bullets. I am no expert, but that is what I take away from the differences.

[dahermit]

The 6mm creedmoor case was based on the 6.5 creedmoor case. Which was based on the 30 TC case. The 243 is based on the 308 case.

And the 30 TC case is based on a shortened .308 case so wouldn't the .243 Case be longer than the 6mm Creedmoor case?

[dahermit]

150 fps. Creedmoor has an 8 twist, and is spec'ed at higher pressure.

6mm Creedmoor SAAMI pressure = 62,000 PSI
243 Winchester SAAMI pressure = 60,000 PSI
6mm Remington SAAMI pressure = 62,000 PSI

Handloaders do no usually have access to pressure testing equipment. Therefore, they usually keep increasing the powder charge incrementally until pressure signs appear and then back off (or at least that is how it was done in my day). In modern rifles, would not the pressure signs appear in those cartridges using identical rifles at the same pressure?

[dahermit]

The creedmoor launches same weight bullets about 100 fps faster than the 243 win.

That would seem to put the 6mm Creedmoor at the level of a 6mm Remington then, would it not?

[kilotanker22]

Yep

[kilotanker22]

The 243 case is like .125 longer than the Creedmoor I believe.

[old roper]

Myself I think 6CM good case and should take care of those that don't like short neck 243 or twist.

I shoot 243 and 243AI both with good barrels and I can see 6CM if I wear out barrel on 243. David Tubbs shorten 243 case for 6xc then you fire form 22-250 case and it had 30 degree shoulder.

[std7mag]

Mikejones,
I'll see your "100 fps gain over the 243" and raise you another 100fps with same 243 Win using an appropriate powder and staying within pressure.

Ask Kilo how...

[dahermit]

I'll see your "100 fps gain over the 243" and raise you another 100fps with same 243 Win using an appropriate powder and staying within pressure.

And another 100 fps by going to the 6mm Remington. For the life of me, I do not see the appeal of a 6mm Creedmoor. Or the 6.5 Creedmoor for that matter...but it seems to be the hot chambering now for bolt rifles.

[ammo.crafter]

I'll stick with my 98 Mauser converted to Remington 6mm.

[std7mag]

I could possibly give your 6mm Rem another 100 fps too.

[Chainsaw.]

Everyone keeps talking about the case and its attributes, but what comes to my mind is the most important aspect, and that is what does it doi down range? I am reminded of the test that someone (military?) did with 308 vs 6.5 creedmoore at long ranges. IIRC they shot a high number of rounds at a long distance, my memory is crap so I don’t recall the distance either but lets just say 1000 yards. Across a large number of rounds fired in identical conditions the 6.5 proved to be more accurate.

So, what does more of what you want down range? Thats the real question.

[std7mag]

In this case, there is no "better" down range.
A 6mm bullet weighing 105gr is same as a 243 bullet weighing 105gr.

7mm-08 kicks a 308 square in the coconuts at long range.

The discussion isn't 308 vs Manbun. It's 243 vs Manbun Lite.

[Chainsaw.]

Right over your head.

[dahermit]

Everyone keeps talking about the case and its attributes, but what comes to my mind is the most important aspect, and that is what does it doi down range? I am reminded of the test that someone (military?) did with 308 vs 6.5 creedmoore at long ranges. IIRC they shot a high number of rounds at a long distance, my memory is crap so I don’t recall the distance either but lets just say 1000 yards. Across a large number of rounds fired in identical conditions the 6.5 proved to be more accurate.
So, what does more of what you want down range? Thats the real question.

We do not want to trust in an anecdote as evidence. We do not know how many rifles were used, if there were more than two rifles involved, test conditions, if the rifles were identical save for chambering etc., etc.

Such stories have no value in comparing one chambering to another...my uncle Fudd can sling B.S. with the best of them if we just want to be entertained.

[jmr40]

You CAN make a 243 and 6CM cartridges to pretty much the same thing. But it's more than the cartridge case. Rifles chambered in 243 were designed from the ground up to shoot "HUNTING" bullets in 55-100 gr weights. The 100 gr "HUNTING" bullets were relatively short and could be shot from most 243 barrels.

But target shooters wanted to shoot 108-115 gr "TARGET" bullets which are much LONGER. Even a 100 gr "TARGET" bullet is much longer than a 100 gr "HUNTING" bullet. The longer "TARGET" bullets won't fit in a traditional 243 magazine or chamber unless they are seated so deep they limit powder capacity or create a dangerous over pressure round. Initially target shooters were using 243's modified with longer magazines, longer throats, and barrels twisted for use with the "LONGER" bullets, which if done right creates exactly the same effect as 6CM.

Rifle manufacturers could have modified their 243 rifles to shoot the "LONGER" bullets and they could have offered factory loads with those bullets. But those rifles wouldn't have shot standard 243 ammo as accurately. And it might create a dangerous situation if the newer ammo with longer bullets were fired from an older 243 designed for hunting bullets

It was really much simpler, and safer to offer shooters who wanted to shoot longer bullets a different cartridge to do so. And BTW, this is exactly the same reason we have 6.5 CM and 260. Both of the CM versions simply offer off the shelf rifles and ammo that do the same thing that target shooters have been doing with modified 243 and 260 rifles and non-standard loads.

[RC20]

Its pretty much a wash for most of us.

Target shooters eek out a living on the tiniest fine line cuts so anything that increases that for them is what the 6 and 6.5 CM are all about.

A poor 6 CM barrel will shoot worse than a good .243 barrel. Back to the issues, its a system, shooter, cartridge, gun (all aspects) and ammo (more tiny details)

I have a 308 barrel that is so picky it doesn't even like a Lapua case.

The other aspect is marketing and kind of like Sig who got a 357 named after them and the Glock 45 GAP that is gone the way of the dodda bird.

Shoulder improves supposedly is more efficnet and you gain a bit of space for powder. all vastly overated for most of us I think.

If you look at the 7.5 Swiss or the 8mm Mauser they had that 100 years ago.

One is still widely used as it was widely distributed. the other no matter how modern is pretty niche.

[kilotanker22]

Originally Posted by std7mag

Mikejones,
I'll see your "100 fps gain over the 243" and raise you another 100fps with same 243 Win using an appropriate powder and staying within pressure.

Ask Kilo how...

Um yeah. I have had 3 6.5 Creedmoors. With a certain powder I was able to to beat max loads of other powders by 100fps plus. With no signs of pressure. Of course with a 260 or a 243. I would not be able to make that claim. These were compressed loads with the bullets seated way further out of the case than I could have loaded with a 260. Without a custom barrel and long action magazine.

I very much like the Creedmoor cartridges. For the same reason that I will buy a 300 PRC as soon as I can get a factory rifle chambered for one.

Although to each their own. I can definitely see the benefit of the shortened case and faster twist factory barrels. Especially with the new trend of Low Drad match style hunting bullets. Although I wouldn't say one is superior to the other. You would be pretty naive to believe that there is no advantage.

As far as the 6Creedmoor or the 243 win. Either would be ok. I have loaded for a couple 243 rifles. With excellent results. I don't have any 6mm rifles anymore. Why? Because I feel like the heavier, higher BC bullet availability and energy downrange of the 6.5 is a definite advantage over either of the cartridges that the OP listed.

[std7mag]

I'm thinking someones been sniffing too much 2 stroke exhaust fumes...

I had this gun once, at band camp. Was nothing like what your talking about. But it would beat this other kids rifle, that he didn't have at the time.

When comparing apple to apple, you don't bring up brick to golfball.

Kilo, say the word. Savage in 300 PRC is easy!

[kilotanker22]

Originally Posted by std7mag

I'm thinking someones been sniffing too much 2 stroke exhaust fumes...

I had this gun once, at band camp. Was nothing like what your talking about. But it would beat this other kids rifle, that he didn't have at the time.

When comparing apple to apple, you don't bring up brick to golfball.

Kilo, say the word. Savage in 300 PRC is easy!

Yeah I got a little off topic there, but my comments about the 6.5 Creedmoor and the 260 REM directly related to the OP's topic. I was trying to portray my preference for the Creedmoor case as opposed to the 308 based cases. By putting a comparison out there that I have direct experience with and also relates to the comparison at hand. So to me it really was still comparing apples to apples... Just more like Red delicious and Cortland