What is a 6mm Creedmoor
First off, the 6mm? The 6mm, refers to the bore diameter of the barrel, more specifically a .243″ or 6mm bullet diameter. The bullet diameter is .243″, the same as any other .243 or 6mm centerfire cartridge like the 243 Win, 6mm Remington, 6XC, 6GT, 6mm BR and 6mm Dasher. The Creedmoor in 6mm Creedmoor is named for the fact that it comes from a 6.5mm Creedmoor which has been necked down to accept a .243 bullet, the Creedmoor in 6.5mm Creedmoor originally comes from Creedmoor Sports, for whom the 6.5mm Creedmoor cartridge was developed by Hornady and Creedmoor Sports jointly.
The 6mm Creedmoor or 6Creed as some call it, was a natural evolution as with almost any other 6.5mm Creedmoor that was eventually necked down to 6mm for faster muzzle velocities and lower recoil for PRS style racegun competitions.
The oldest actual mention of the idea for a 6mm Creedmoor that is laid down in historical record, is this post on Snipershide by user skeetlee, known in real life as Greggory Lee Gardner of Lee Gardner Precision. He mentioned that he wants to invent a new cartridge by necking down a 6.5mm Creedmoor to a 6mm and that it would make a mean varmint cartridge. The fact that this was said on such a knowledgeable forum, with no objection by anybody and the first person to mention that such a reamer has been made before by PT&G was in 2010 on that thread. So although John Snow from Outdoor Life magazine and website has claimed that it was his idea as early as 2007 but that they only made such a rifle later in 2009 for an article that appeared in the magazine in 2010 (earliest mention I can find of an Outdoor Life magazine that contains an article of a 6mm Creedmoor is of the Aug 2011 issue), that cannot be verified, so we will officially going with Mr Lee Gardner as the first documented person to think of the idea of the 6mm Creedmoor.
There is also talk on a post over on Accurate Shooter forum by a person calling himself gnoble, that he built this or a very similar cartridge back in 2001 already by shortening a 243 Mashburn (I think he meant a 244 Mashburn). Depending on how much shorter he actually made it, this could be the case as the rare wildcat 244 Mashburn cartridge also had the same rim, also very little tape in the case body, and also featured a 30 degree shoulder, but this again could not be verified other than that claim.
6mm Creedmoor Brass
Initially to create 6mm Creedmoor brass cases, one would simply neck down high quality 6.5 Creedmoor brass with a good full length sizing die and enough case lube. Thankfully though, there are many companies now including Hornady, Peterson, Starline and a few more, making 6mm Creedmoor brass cases. There is also 6mm Creedmoor SRP brass available offering small rifle primer holes for shooters preferring small rifle primers, the only benefit I have actually been able to prove with small rifle primer brass, is that the primer pockets take longer to stretch when running hot loads.
Ultimately, it is the shooters that decide which new wildcats or cartridges become popular and are there to stay and which aren’t. They decide that with their own hard-earned money. Looking at the immense popularity of the 6mm Creedmoor in recent years, especially in the PRS racegun and other fieldshoot type competitions, the availability of factory ammo and factory chambered rifles in it, it would appear to be here to stay, with many claiming it displacing the legendary .243 Winchester.
People quickly make jokes about the 6.5 Creedmoor cartridge when they hear a shooter has it, but you never hear anybody joke about the 6mm Creedmoor, as there is no denying the seriousness of a 108gr ELD-M bullet charging down range at 3100+ fps.
Create Your Own
There are many large scale manufacturers making a 6mm Creedmoor Factory Rifle, including Ruger, Tikka and Howa to name just a few.
Creating a 6mm Creedmoor rifle custom or from one of your current rifles is also fairly simple, you simply use the action of a rifle with a compatible bolt face and action length as can be seen on our bolt face database, and then have a gunsmith chamber and fit a .243 barrel to it. The gunsmith would need a 6mm Creedmoor reamer to create a chamber in the barrel for it. My personal 6 Creed is a Remington 700 Stainless Action from a rifle originally chambered in 308 Win, the action was then trued, fitted with a Lothar Walther .243 barrel in 1-7 twist on it with the chamber cut for a 6mm Creedmoor. It has served me well in both the NRL and PRS league, and I have taken more than 30 different animals with it successfully.
6mm Creedmoor Dies
All the die manufacturers including Hornady, Lyman, Redding, RCBS and other make 6mm Creedmoor Dies, but out of all of them that I have used, I still prefer the Redding as the best 6mm Creedmoor Dies for sale, because of the quality of the product, and then the design of the expander which works very well for me. In fact, I now only have RCBS dies for all of my calibers except the rare wildcat calibers that RCBS do not make dies for.
6mm Creedmoor Twist Rate
For the the heavier bullets like the 108gr ELD-Match, Hornady recommends 1-8 inch twist barrel, which is what I am also shooting them with in my PRS 6mm Creedmoor rifle and it suits those bullets perfectly.
For 75gr and lighter competition and varmint bullets, a 1-10″ twist rate would be fine.
6mm Creedmoor for Hunting
The general rule of thumb for caliber to animal size, is 6mm, 243 Win, 270 Win and up for any smaller CXP2 type antelope, and 30-06 Spingfield or larger for CXP3 medium to large game. That is not cast in concrete however and many larger CXP3 animal have been taken with 6mm Creedmoor rifles, but usually either at long range with high-shoulder shots, or close range with headshots, but this is not recommended.
The 6mm Creedmoor can be seen as the replacement for the .243 Winchester, so all the animals that was generally considered fine to be hunter with it, the 6mm Creedmoor can be used to hunt with just as well. As can be seen with the Kudu bull taken at 180 yards late evening with a well place head shot.
What the 6mm Creedmoor absolutely excels at though, is those same small to medium CXP2 type animals, but at long range, with consistently expanding high-BC match bullets like the Hornady 108gr ELD-M or the Berger 105gr Hybrid Target. For these shots, high shoulder is recommended. First you will see the video showing a guy that has hunted hundreds of those sized animals with his 6mm Creedmoor at long range and high shoulder shots. The next video, you will see the explanation of why a high-shoulder shot, with such a bullet is the recommended shot and with expanding match bullets.
6mm Creedmoor for Competition
With similar advantages for precision rifle competition shooting as the 6.5 Creedmoor, the 6mm Creedmoor is also a superb competition cartridge, especially for small caliber long range shooting and PRS competition shooting. It can accommodate the newer, longer and heavier 6mm bullets that offer good ballistic coefficients, whilst still shooting them a fast muzzle velocities without too much recoil. Overall a superb if not one of the best PRS and racegun competition cartridges.
If we look at the debate of the 6mm Creedmoor vs 6.5 Creedmoor for PRS shooting and competitions, both have their own merits. The 6mm Creedmoor being faster, less recoil and flatter shooting, the 6.5 Creedmoor having larger and better BC bullets, allowing the spotting of bullet trace, hits and misses better on target and doing better with the higher BC bullets out at extended distances, and greater availability of bullets and components.
6mm Creedmoor Ballistics
What makes the 6mm Creedmoor ballistics so favorable, is that it lends itself perfectly to fully exploit the newer generation of high BC 6mm bullets available on the market. Coupled with fast twist rate barrels, the 6mm Creedmoor has the powder capacity to get 3100+ fps velocities from these long, and heavy-for-caliber bullets. Sending a 108gr high-BC bullet downrange with a muzzle velocity of 3200 fps, with a relatively low recoiling rifle, makes for exciting long range shooting and hunting. Now add to that the 30 degree shoulder of the Creedmoor case design, and you also do not have brass that grows with every firing, and so you easily get over 10 reloads out of a 6mm brass case if you anneal between each firing. Ballistically speaking, the 6mm Creedmoor is the .243 Win of the next century.
6mm Creedmoor Barrel Life
Barrel life variable depend on your rifle, barrel, load, velocity and bullet. Many factors determine the number of shots a barrel can take before the throat and rifling of the barrel become worn to a point where the accuracy wanes, usually evident through inconsistent groups or sudden slower muzzle velocities. We have found some 6mm Creedmoor shooters pushing the bullet speeds in excess of 3000 fps to get around 2000 shots out of their barrels, and some have been able to extend that with proper barrel care life letting the 6mm Creedmoor barrel cool between firing strings, and hBN or other coatings on the bullets, or using the Tubb Throat Maintenance System bullets every few hundred shots.
There have been a few surprises regarding the barrel life of a 6mm Creedmoor rifle, and that depends on various factor including what type of barrel it is and from which material combination it was made, the cleaning methodology applied to the barrel, and the loads shot through the barrel. Like this unbelievable 6mm Creedmoor of PRS Pro Shooter Jake Millard from Panhandle Precision who has recorded 2500 rounds through his 6mm Creedmoor and the rifle is still grouping well and shooting very low SD and ES as can be seen below:
6mm Creedmoor Reloading Data
For safe reliable reloading data to start your load development journey with your 6mm Creedmoor, I would recommend working with the reloading data provided by either your powder manufacturer, like the Hodgdon reloading data portal, or the reloading data provided by your chosen bullet manufacturer. This will give you a good, safe starting minimum load to work upwards from.
6mm Creedmoor vs 243 Winchester
The case volume of the 6mm Creedmoor is on average 51.7gr H2O, with a case length of 48.77mm, and for the 243 Winchester of 53.6gr H2O with a case length of 51.94mm. The fact that the case length of the 6mm Creedmoor is shorter than that of the 243 Win, but that it can be loaded to a higher rated max pressure of 62 000 PSI compared to the 60 000 PSI of the 243 Win, means that the newer, more modern longer bullets with higher BCs can be loaded further out in the 6mm Creedmoor before reaching the magazine max overall length, compared to the 243 Winchester. This means an average of 100 to 200 fps higher muzzle velocities from the better BC bullets out of the 6mm Creedmoor, so it beats the 243 Winchester in the energy, drop, windage and ballistics departments.
Also thanks to the 30 degree shoulder on the 6mm Creedmoor, compared to the 20 degree shoulder of the 243 Win, means that the brass does not expand and lengthen upon firing in the 6mm Creedmoor like on the 243 Winchester, so you have longer brass life before case head separation happens, and also the 6mm Creedmoor barrel is not burned out as fast as the steeped shoulder angle means the junction of the burn is further from the throat of the barrel chamber.
The only place where it was always claimed that the .243 Winchester won the 6mm Creedmoor, was with ammo availability. However with the huge commercial success of the 6mm Creedmoor, it has caught up to the 243 Win, in ammo availability and often with better performing factory ammo offerings too, so now the 6mm Creedmoor is by far the clear winner between the two in the 6mm Creedmoor vs 243 Win debate.
6mm ARC vs 6mm Creedmoor
The new 6mm ARC from Hornady is currently gaining huge popularity as the newest 6mm on the block, and although it has it’s merits, ballistically it does not come close to the 6mm Creedmoor ballistics as it cannot hold nearly as much propellant. It is more suited for the shorter action rifles like AR-15s and the Howa Mini Action rifles. But when it comes to long range, and standard short actions, the 6mm Creedmoor beats the 6mm ARC quite far.
6mm Creedmoor Name
The 6mm Creedmoor is also often misspelled as 6mm Creedmoore or 6 Creedmore, it is also often called the 6-6.5 Creedmoor denoting the main 6.5 Creedmoor cartridge that it was developed from.
Why the 6mm Creedmoor of all the 6mm cartridges?
The 6mm Creedmoor is often the best option out of all the 6mm cartridge options available, for a number of reasons. Many shooters already have a 6.5mm Creedmoor rifle, so a simple barrel swap will turn the rifle into a 6mm Creedmoor. Then can just neck down their existing 6.5mm Creedmoor brass and use that. The 6 Creed can be loaded up or down. Up to achieve higher velocities to get the heavy 105gr and over high-BC 6mm projectiles to the velocities needed to get them out to distance, without having a heavy recoil. For PRS competition shooters, it can also be loaded down to the 2800 fps range to bring recoil down even lower so they can easily follow through their own shots, making it easier to spots hits or misses, and saving barrel life in the process. The 6mm Creedmoor brass is also becoming readily available in Small Rifle Primer and Large Rifle Primer configurations, so that depending on component availability of primers, it makes it easier to be able to use either.