What is a 6mm Dasher

The 6mm Dasher is a centerfire rifle cartridge designed for long-range shooting. The 6mm refers to the caliber or bore of the bullet, which is a 6mm or .243 inch diameter. The Dasher is not just a pretty catchy name given to it by the creators to differentiate it from the 6mm BR and BR variants from which it was wild catted, it actually has a backstory too, but more on that below.

The Creation

According to an article in the February 1999 edition of Precision Shooting Magazine, the 6mm Dasher was a then brand new wildcat thought up and created by gunsmith Dan Dowling and friend Al Ashton. The “DASHER” in the name was deduced by combining “Dan” and “Ashton”. They actually first developed the .22 Dasher and then later to a 6mm Dasher.

There are no 6mm Dasher SAAMI specifications, even though it has been around for over 20 years and has become massively popular will all of the varieties of precision rifle shooting sports, so it may be unlikely they will ever publish them, unless they get pressure from rifle manufacturers.

6mm Dasher Specifications

6mm Dasher Brass

Initially to create brass for 6mm Dasher cartridges, was done by fire forming 6mm BR brass. Thankfully though, there are many companies now including Peterson, Alpha Munitions and a few more, making 6 Dasher brass cases. The 6mm Dasher trim length for cases is 1.535″.

New Cartridges

Why create the 6mm Dasher in first place when there is already the 6mm BR and multiple variants of it. Well, for the certain benefits it provides over the 6mm BR if those are required by your shooting style. The 6mm Dasher can launch the popular high-BC 105/108gr 6mm bullets to around 3000fps with roughly only around 33gr of powder, and whilst the 6mm BR can be pushed to this level, this severely decreases it’s brass and Barrel life because of the dangerous levels of pressure needed to get to that level in the BR. In the 6mm Dasher however, that velocity with those bullets is still attainable without dangerous pressure levels, meaning longer brass life and reasonable barrel life. With the 40 degree shoulder, similar to Ackley Improved cartridges, the brass also does not stretch with every firing and need not be trimmed often.

Create Your Own

So far, there aren’t really any large scale manufacturers making a chambered 6mm Dasher Factory Rifle, however, there are somewhat off the shelf 6 Dasher rifles available from companies custom rifle building companies.

Creating your own 6mm Dasher chambered rifle is also fairly simple, you simply use the action of a rifle, or 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 a 6mm barrel to it, or get a prefit barrel chambered in 6mm Dasher for it. My personal 6mm Dasher, was a full build bought from Short Action Customs, where they chambered and fitted the barrel for me on the action, in a stock, with a trigger. So I basically bought a ready to shoot 6 Dasher rifle from them and I am still completely in love with it.

6mm Dasher Reloading Dies

6mm Dasher Twist Rate

Because the dasher was designed to get the most out of the longer, high-BC 6mm bullets with as little powder as possible, it is recommended to get it in a 1-8″ twist or smaller, with my preferred being a 1-7″ twist rate barrel. This ensures that those long bullets are stabilized sufficiently even at the relatively lower velocities.

6mm Dasher for Hunting

Although some that are used to the ultimate velocity 6mm cartridges like the 6mm Creedmoor and the .243 Win, don’t really think of the 6mm Dasher as a hunting cartridge, don’t let that fool you. It can be a very formidable hunting round with the correct loads and bullets.

My personal favorite hunting bullets in my 6mm Dasher is the Sierra 90gr Gamechangers. They offer a great BC for hunting bullets, expand consistently, and they are very effective at delivering lethal shots, especially when I push them around the 3000 fps muzzle velocity mark.

There aren’t many videos online documenting hunting shots with the 6mm Dasher, but just hang on, I have now made that another goal of mine, so watch me adding more 6mm Dasher hunting shots and kill-shots videos pretty soon.

6mm Dasher for Competition

Competition, being the actual main purpose for the creation of the 6mm Dasher, is where it shines. Especially in precision rifle, racegun and PRS style competitions, where the low recoil, high BC and relatively good barrel life of the Dasher because of high competition shot count are great pros. Obviously I am not the only one to think this, as looking at the statistics for the cartridges the pros used in the 2022 PRS season, you will see that by FAR the majority of the top shooters used the 6mm Dasher, with more than 50% of the top 10 shooters too.

6mm Dasher Barrel Life

The barrel life of a 6mm Dasher can vary depending on a number of factors, including the quality of the barrel steel and manufacturing processes, the type of ammunition used, the pressure of the load you are shooting through it, and the shooting conditions, with things like leaving a barrel to cool down between shots and so on. In general, you can expect to get anywhere from 2 500 to 4 000 rounds from a 6mm Dasher barrel.

With proper care, you can expect to get many years of use out of your 6mm Dasher barrel, more so than with the hotter 6mm cartridges like the 6mm SLR, 6mm Creedmoor, .243 Win and the 6mm GT.

Here are some specific examples of barrel life for 6mm Dasher barrels:

• A shooter on the Shooters’ Forum reported getting 2,300 rounds from a Lilja barrel before it started to show accuracy degradation.
• Another shooter reported getting 3,500 rounds from a Krieger barrel before it needed to be replaced.

As you can see, there is a wide range of how many shots of barrel life for 6mm Dasher barrels. The best way to get the most out of your barrel is to use high-quality gunpowder, clean it regularly with the correct technique and products, and avoid shooting long strings of shots overheating the barrel often.

6mm Dasher Load Data

Load data is specific to every rifle and every person depending on the components you want to use like the bullets or brass, and depending on the type of shooting you want to do with it. Using someone else’s load data could be dangerous, so I always recommend getting the load data from the manufacturer of your chosen propellant or bullet, starting from their minimum recommended load and working your way up to your desired muzzle velocity and node.

That being said, the 6mm Dasher has gained so much popularity because among other things, it is very forgiving and very easy to find a load for that groups well and consistently. The most common powders I found that was used by competition shooters in 6mm Dasher loads were Hodgdon Varget and VihtaVuori N150.

So here are a few proven loads that group well and are not close to the maximum pressure of the cartridge:

6mm Dasher load data for the Berger 105gr Hybrid bullet:

• Powder: Hodgdon Varget
• Charge weight: 32.3-32.5 grains
• Case: Lapua brass
• Primer: Federal 205 Small Rifle
• Muzzle velocity: 2925-2975 fps from a 26″ barrel

Load data for the 6mm Dasher with the Berger 105gr Hybrid bullet:

• Powder: IMR 4895
• Charge weight: 32.0 grains
• Case: Lapua brass
• Primer: CCI 450 Small Rifle
• Muzzle velocity: 2900 fps from a 26″ barrel
• Powder: H4350
• Charge weight: 31.5 grains
• Case: Lapua brass
• Primer: CCI 450 Small Rifle
• Muzzle velocity: 2875 fps from a 26″ barrel

6mm Dasher Magazine Feed Issues

There has been a lot of talk online and I have seen many people struggle with magazine feeding issues with a 6mm Dasher or other 6mm BR variant cartridge from normal short action AICS or AW mags. This depends on a lot of factors, not just on the 40 degree shoulder angle as many think. Most of the Sherman and Ackley Improved wildcat cartridges also feature 40 degree or even steeper shoulder angles and they do not struggle to feed that often, so I would be more inclined to think that the feeding issues if they occur have more to do with how short the case is compared to the length of a short action, or maybe that in combination with the steep shoulder angle. It has a lot to do with the shape of the feeding lips of the magazine, the feeding ramp of the action and the feed-style of the bolt.

Whatever the cause may be, it is very easily solved with a Dasher or BR magazine conversion kit from Primal Rights or one of the other manufacturers. As has been proven by the majority of top PRS shooters successfully using the 6 Dasher in the PRS league, where magazine feeding issues could not at all be tolerated as they will ruin a competitors chances to finish a stage on time. So if you 6mm Dasher magazine feed issues, get a kit, solve them, and get shooting.

6GT vs 6 Dasher

The 6mm Dasher and the 6mm GT are both high-performance 6mm cartridges that are popular for long-range shooting. They are both evolutions on the 6mm BR case, but the 6mm GT was based on the .22-250 case, has a longer neck and a slightly different shoulder angle.

Here is a table comparing the two cartridges:

As you can see, the 6mm GT has a slightly higher case capacity than the 6mm Dasher. This gives the 6mm GT the potential to achieve slightly higher velocities if that is what you are after, but at the cost of barrel life of course. However, the 6mm GT also has a slightly longer overall length, which can make it easier to feed from a magazine than the shorter BR variant cartridges. This isn’t necessarily an issue anymore as there are sufficient magazine options and conversion kits available allowing the BR variant cartridges like the 6mm Dasher to feed very reliably as can be seen in the PRS scene.

Ultimately, the best cartridge for you will depend on your specific needs and preferences. If you are looking for a cartridge with the absolute best performance velocity, then the 6mm GT is a good choice, but is that little gain worth it compared to the cost in barrel life it then gives? Only you can decide that. However, if you already have a 6mm GT rifle, or a 6mm Dasher rifle, the difference would be too small to validate the cost of another whole setup, or changing over to the other in my opinion.

6mm Dasher vs 6mm Creedmoor

The 6mm Dasher and the 6mm Creedmoor are both popular precision rifle cartridges, but they have different strengths and weaknesses.

The 6mm Dasher has a smaller case capacity than the 6mm Creedmoor, which means it can’t achieve the same higher velocities, but gets near it with much less gun powder usage. This makes it a good choice for high volume competition shooting. The 6mm Dasher also has a slightly longer barrel life than the 6mm Creedmoor, due to the lower pressures it generates.

However, the 6mm Creedmoor has a wider range of bullet options available as it has the needed extra powder capacity to push the heavier bullets at higher velocities, and it is easier to find factory ammunition for.

Ultimately, the best cartridge for you will depend on your specific needs and preferences. If you are looking for the absolute highest velocity for longer range or hunting, then the 6mm Creedmoor is a good choice. If you need a cartridge that is more versatile and easier to load for, then the 6mm Dasher is a better option.

Here is a table comparing the two cartridges:

The 6mm Creedmoor is the speed demon out of the two, and often called the .243 Win for the next century. It has now become widely available in both factory rifle chamberings and factory ammo, so if availability and ultimate velocity are big considerations for you, the 6mm Creedmoor will serve you well.

If pure competition shooting is your main goal, especially in race gun or bench rest style shooting, the 6mm Dasher is known to be much easier and more forgiving to tune and find a load for, and combined with better expected barrel life, the 6mm Dasher should be your cartridge of choice.

6mm Dasher vs 6mm ARC

The 6mm Dasher has a slightly larger case capacity than the 6mm ARC, which allows it to achieve slightly higher muzzle velocity and energy. However, the 6mm ARC is slightly more efficient, meaning that it can achieve similar performance with less powder.

The 6mm Dasher is also currently still slightly more popular than the 6mm ARC because it has been around longer, but both cartridges are readily available, and with the Hornady marketing machine behind the 6 ARC, the fact that there is already factory rifles and factory ammo available for it, both mean that it will be very soon to overtake the Dasher in popularity, but most often for different reasons and goals.

Ultimately, the best cartridge for you will depend on your specific needs and preferences. If you are looking for the cartridge with the highest performance in bench rest or PRS type competition shooting from a standard .308 bolt faced rifle, then the 6mm Dasher is the better choice. However, if you are looking for a cartridge that is more efficient available in factory ammo, possible to get in certain mini-action, can work in semi-auto rifles, then the 6mm ARC is a good option.

Here are some additional factors to consider when choosing between the 6mm Dasher and the 6mm ARC:

• Recoil: The 6mm Dasher has slightly more recoil than the 6mm ARC, due to the smaller case head of the ARC and slightly lower powder capacity. This may be a factor if you are a recoil-sensitive shooter, but both these cartridges are so low on the recoil scale, that it becomes negligible at this point.
• Availability: Both cartridges are readily available, but the 6mm Dasher is slightly more popular among the reloading and bolt-action community. This means that you may have a wider selection of reloading components available in 6mm Dasher. The 6 ARC however already has factory Hornady ammo and some factory rifle chamberings available which the Dasher does not.
• Cost: The cost of rifles and ammunition in both cartridges is similar.
• Ballistics: The 6mm Dasher has slightly better ballistics than the 6mm ARC based only on higher muzzle velocities achievable. This means that it can reach targets further out with less drop.
• Precision Shooting Sports: The 6mm Dasher is a popular cartridge in PRS competitions, while the 6mm ARC is not as common. This may be a factor if you plan to compete in PRS.

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