So I've been trying to do research on these and while there are many articles comparing the two calibers they are almost always using factory ammo with different grain weights or bullet profile or even different style guns all together. So what I want to know is there a scientific, evidence based study on these two? Ie: hand load both calibers with the same projectile and the same charge weight and then shot out of nearly identical guns, and then do a comparison. I would like to know if there was any actually study done like this because I can't see what actual advantage 6mm could have over the 243, and it just seems the way the "studies" are being done it's just meant to backup the marketing hype.
6mm Creedmoor and .243 WIN, is there really a difference?
- Thread starter welder179
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6cm has a faster twist rate in factory rifles to take advantage of heavy VLD bullets that would keyhole in a factory 243 twist rates.
I find the Creedmoor cartridges are targeted to the off the shelf crowd...you can get good long range factory rifles and ammo at reasonable prices. That's the appeal.
I find the Creedmoor cartridges are targeted to the off the shelf crowd...you can get good long range factory rifles and ammo at reasonable prices. That's the appeal.
I build a 6x47 Lapua (6mm Creedmoor) 7 years ago with 1-7.5" barrel twist and it's roughly 30% accurate, is more efficient and allow the use of high BC bullets.
The relative advantages 6mm Creedmoor are:
For up to 500m paper punching for extra low recoil long range deer hunting it's unbeatable.
Impotant: Make sure to consider buying both a 308 Win (superior versatility) and a 223 Rem (accurate and inexpensive to shoot) before jumping to more "specialized high performance" cartridges game like 6mm and 6.5mm Creedmoor.
Alex
The relative advantages 6mm Creedmoor are:
- excellent factory match ammo
- excellent medium game long range hunting ammo
- shorter case length (by 4mm - allows to use high BC bullets)
- sharper angle of shoulder (better for propellant combustion - extra accuracy)
- longer neck (better for accuracy and improves barrel life)
- smaller case expansion ration (improved propellant combustion efficiency)
For up to 500m paper punching for extra low recoil long range deer hunting it's unbeatable.
Impotant: Make sure to consider buying both a 308 Win (superior versatility) and a 223 Rem (accurate and inexpensive to shoot) before jumping to more "specialized high performance" cartridges game like 6mm and 6.5mm Creedmoor.
Alex
A 6x47 lapua is not a 6mm creedmoor it’s simply a 6.5x47 lapua necked down. A 6 creedmoor in nothing more than a 6.5 creedmoor necked down. All great calibers but not the same. And too the ops questions a 6mm creedmoor is a bit better than a 243, nothing wrong with the old 243 but the 6creed is more efficient and will do everything the 243 will do but with less powder, brass will not have to be trimmed as often because of the 30 deg shoulder compared to the 20 deg on the 243, creed case is s not short which will make seating and using the heavy vld bullets easier and not be limited to mag length. Great brass available for both but small primer pocket options for the creed is a nice choice to have.
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Not planning on jumping into anything specialized right now, I just like doing research and having a scientific reason for things. So you say the sharper angle and longer neck help accuracy and barrel life, in what way do these things help? Do you have evidence to back this up? Not criticizing you just trying to seperate fact from fiction/opinion.
It is largely accepted in the target shooting community that short and fat cartridges with steep shoulder and long necks are more efficient, have longer barrel life and are more accurate as a generalization. Look at the 6BR case, for example.
The exact scientific reasons for this are not clearly known, but the anecdotal evidence is very strong. The general idea is the this particular case format burns more of the powder inside the case and not in the throat of the barrel, prolonging barrel life. The long neck also lengthens barrel life and aligns the bullet as it enters the rifling, enhancing precision.
Getting back to the 6 CM vs .243, the Creedmoor will need roughly 42gr of a single base powder like H4350 to push a 105gr bullet to around 3030fps. The 243 will need roughly the same amount of double based powder to do the same, which burns hotter and reduces barrel life. Or you can use 46-48gr of a slower powder to hit the same speed. Hence the 6CM is more efficient, less powder for same velocity.
Go to this link: ht tps://precisionrifleblog.com/2018/12/14/rifle-caliber/ and read the section titled 6BR-Based Cases. Pay attention to the case capacity and muzzle velocity graphs especially.
There are no fast twist 243 factory barrels that I know of, but there was a US shooter winning matches with a custom 243 fast twist barrel. Again, the CM cartridges are a good cheap alternative to going custom, which seems to be the appeal.
I don't buy the magic case design benefits some claim, or "efficiency" where less powder somehow produces higher velocity with similar pressure to larger cartridges.
Sharper shoulders do reduce case stretch, but there are 35 and 40 degree cases out there already that do it even better.
I think I have an idea of why this may be, has to do with fluid dynamics and turbulence and laminar flow. The large case and small neck creates turbulence and makes it difficult for powder to escape the casing, but the long neck creates a smooth laminar flow inline with bore axis. I would think that this would severely reduce brass life then.
If I had the money I would be inclined to built two rifles one in 6CM and the other in 243 with the same twist and then do a real comparison between performance.
Nothing ‘specialized’ about 6mm or 6.5mm chamberings....just less factory ammo options depending on which one.
They reload just like anything else....no magic.
They reload just like anything else....no magic.
Got Juice?
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Steeper shoulder, and shorter length and fatter case "Focuses" the energy of the expanding gasses on a smaller point load (the bullet base) and so the neck tension holding the bullet takes a longer time to start the projectile moving out from the grip, but a shorter dwell time between grip and slipping out of the case. Shaped charges have the same effect in antitank rounds.
Killbillc68
Regular
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- Dawson Creek BC
6 creedmoor for sure. I have 300 Lapua brass coming and a gun being built. Take a look at this pretty sure these guys have put a lot more thought into it then most of us.
https://precisionrifleblog.com/2018/12/14/rifle-caliber/
https://precisionrifleblog.com/2018/12/14/rifle-caliber/
I've shot a decent bunch of 6mm Creedmoor, like 2 barrels' worth, this past season. Honestly, if you're choosing between the Creedmoor and the .243 and you don't already have any components for .243, there's really no reason to go in that direction. I've never shot the .243 but I'd imagine you could get the same performance (or very close) out of it as you can with the Creedmoor but the Creed (assuming same barrel and same twist) is just optimized to run out of an AICS mag. You can talk about the increased efficiency of the case and whatnot but at the end of the day, you have 2 cartridges that will both basically perform the same but one is optimized to run in the standard precision rifle mag, has a very good availability of both factory long rang ammo and a huge variety of brass options and also has purpose-built long range rifles chambered in it (if you're getting a factory rifle instead of custom). It's not really much of a choice at all in 2019, unless you just want to be "different"...
Pick your flavor and stop overthinking it.
Any 6mm other than 6 BR and derivative are destroying troat within 1800 round(if you babysit it). For me in PRS I've tried 243, 6SLR, 6x47, 6 XC and 6 creed and nothing ever survived more than 1400 rounds.
243 win is not a bad choice only if you run H1000 to preserve your troat.
6 creed and 6XC cure abusive case grow and are generally easier to tune than the 243 since they have longer neck.
6x47 is also a nice alternative if you are into neck sizing down brass.
Any 6mm other than 6 BR and derivative are destroying troat within 1800 round(if you babysit it). For me in PRS I've tried 243, 6SLR, 6x47, 6 XC and 6 creed and nothing ever survived more than 1400 rounds.
243 win is not a bad choice only if you run H1000 to preserve your troat.
6 creed and 6XC cure abusive case grow and are generally easier to tune than the 243 since they have longer neck.
6x47 is also a nice alternative if you are into neck sizing down brass.
Killbillc68
Regular
- Location
- Dawson Creek BC
Catch up to Weatherby????
I don’t see why you would pick 243 over any of these.
I love the 6XC and am considering a BR based cartridge for my next build...or maybe stick with the 6XC
Don’t get me wrong 243 is great but if you are serious about PRS you would run what is proven.
Proven by who? Prs crowd? Most bias market on earth dude.. Guys winning would win with any calibers..
243 was proven a long time ago and is more than enough for what prs is. Prs is not rocket science and most of the points are done within 700 m...let's stay down to earth.
Is all the other 6's superior? Performance wise no.
Reloading, factory ammo and ease with mags? Yes totally.
On the other hand I've now settle on the 6 creed because I needed to make a choice and stop chambering barrel for chasing the ghost of "oh that caliber will make me shoot better".
