224 VALKYRIE- Effect of barrel length on velocity
New cartridges come and go. Some catch on while others fade into obscurity. As a gun writer I try to predict which ones will take off. Like anything else, sometimes you are right and many times you are wrong (I was a big fan of the 30AR and 7.62x40WT). Today we are going to look at the 224 Valkyrie, one that I am sure will have some staying power.
The 224 Valkyrie was designed to launch a 90 grain match grade bullet from a standard sized MSR 15 (that’s industry speak for the AR-15/M16 M4 rifle) at around 2,700 feet/second. In theory, with the correct optic and shooter, you could engage targets out to 1,300 yards! Most of the newer cartridges adopted by the larger manufacturers fit into either the MSR 15 or AR10 sized rifles. This should mean that the cartridge will appeal to a wider array of shooters (both semi auto and bolt).
The 224 Valkyrie uses the 6.8mm Remington SPC as parent case. You can find the SAAMI specifications for 224 Valkyrie ammunition here, and, for comparison purposes, 6.8mm Remington SPC here. You’ll note that the case for the 224 Valkyrie is slightly shorter, undoubtedly this allows the cartridge to fit a 90 gr SMK into a MSR 15 magazine.
While the gas gun guys will be attracted to the Valkyrie’s ability to hit targets out to 1,300 yards from a standard sized platform, the bolt gun guys have been just as interested. The Valkyrie offers some positive attributes such as low recoil, short powder-column, and legitimate velocities with a relatively light charge.
When Federal introduced the 224 Valkyrie they were smart. Rather than just introduce one or two loads, they offered four that can address any need. The Fusion MSR is a 90 gr soft point load for deer sized game, the 90 gr Sierra MatchKing is for long range targets, the 75 gr Total Metal Jacket for plinking and the 60 Nosler Ballistic Tip is for Varmints.
Before we get to the test, take time to carefully read the disclaimer below:
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Since the 224 Valkyrie is so new, I had to build a rifle for this experiment. I decided to build a Remington 700 223 bolt receiver.
The 224 Valkyrie uses a .440″ or SPC bolt face. While it is easy to find an SPC bolt for an MSR 15, they are less common in bolt action rifles. I had two options, I could either re-cut the bolt face or order a replacement bolt. I decided to order one and reached out to Dave Kiff of Pacific Tool and Gauge and ordered a custom made, one piece stainless steel bolt with a Sako style extractor.
For a chamber reamer and headspace gauges I ordered one from Dave Manson of Manson Precision Reamers.
I decided to use a Shilen Select Match stainless steel barrel for this test. I’ve used them before and they provide solid results. One quick caveat though, SAAMI recommends an optimal twist of 1:7″. I have one 1:7″ .224 barrel in inventory I plan on using for my actual precision rifle build, so, I decided to use the more readily obtainable 1:9″ twist. This means the velocity numbers should be the same, however, the 90 grain bullets wouldn’t be stabilized. Since my plan was primarily to record velocity, I figured this was a compromise I could live with.
I profiled, threaded and chambered the barrel on my new Precision Matthews PM-1440 GT lathe. I love this lathe! I turned the barrel to a straight profile (~.950″) to allow for easy attachment of the MagnetoSpeed V3 barrel mounted ballistic chronograph. I also added a .040″ wide groove at each 1″ increment to serve as a cutting guide for the shortening of the barrel. (You can visit Precision Matthews here)
The finished rifle, post experiment:
Build parts are as follows:
- Remington 700 short-action receiver
- Shilen select match barrel
- Timney Model 510 trigger
- MDT M700 scope rail
- MDT LSS-XL GEN2 for Remington 700
- MDT Skeleton stock
- MDT polymer 223 magazine modified to work with the 224 Valkyrie
- PTG one piece bolt
- GGG Scope mount
- Sightron scope
- Harris bipod
Even though this rifle was built to be cut up, it still handled very well. The new MDT LSS-XL GEN2 chassis is outstanding, especially when it is coupled with the Skeleton stock. The original LSS-XL was great, but on the GEN2 they widened the fore end significantly. I could have run a straight 1.250″ profile tube in this chassis.
I gathered four different types of factory Federal 224 Valkyrie ammunition, the 90 gr Sierra MatchKing (SMK), 90 gr Fusion soft point (SP) (referred to a Fusion MSR), 75 gr Total Metal Jacket (TMJ) and 60 gr Nosler Ballistic Tip Varmint (NBT). After a brief barrel break in and zero, I fired 5 rounds of each cartridge at each barrel length (except the 75 TMJ, I fired 4 rounds at each barrel length due to limited resources). I recorded the average muzzle velocity and standard deviation for each ammunition and barrel length combination and cut the barrel back 1 inch and repeated the process. I recorded barrel lengths from 28″ to 16.5″ (I try to save these barrels as finished 16″ tubes so they don’t go to waste).
I did not re-crown the barrel since I wanted to conduct the experiment on the same day in the same temperature and would have had to leave the range to head back to the shop each time. In practice, I haven’t found the barrel’s lack of a crown to be detrimental to results. Any burrs were removed with a NOGA deburring tool prior to shooting the data for the next barrel length.
During the test, temperature was 45F.
When you examine the line graph above, you’ll note a fairly consistent rate of change as the barrel length decreases. This is something we don’t see for many cartridges, which will show a more pronounced drop on one end or the other of the chart.
Results for individual loads
In the following tables, BBL indicates barrel length in inches. MV indicates muzzle velocity in feet/second, SD indicates standard deviation in feet/second, CHG indicates the change in average muzzle velocity from the previous barrel length and CHG 28″ indicates the total change in muzzle velocity from the 28″ long barrel.
Federal Fusion MSR 90 gr Soft Point
The 90 gr Fusion Soft Point had a muzzle velocity of 2,797 feet/second at 28″ and 2,561 feet/second at 16.5″ for a loss of 236 feet/second. The average loss of muzzle velocity was 20.5 feet/second per inch of barrel length.
Federal Premium 90 gr SMK
The 90 gr SMK had a muzzle velocity of 2,782 feet/second at 28″ and 2,541 feet/second at 16.5″ for a loss of 241 feet/second. The average loss of muzzle velocity was 20.9 feet/second per inch of barrel.
American Eagle 75 TMJ
The 75 gr. Total Metal Jacket had a velocity of 3,065 feet/second at 28″ and 2,817 feet/second at 16.5″ for a loss of 248 feet/second. Average velocity loss was 21.6 feet/second per inch of barrel length.
Federal 60 gr NBT
The 60 gr Nosler Ballistic Tip Varmint had a muzzle velocity of 3,395 feet/second at 28″ and 3,065 feet/second at 16.5″ for a loss of 330 feet/second. Average velocity loss was 28.7 feet/second per inch of barrel length.
How does barrel length affect bullet drop and wind drift?
To show how barrel length affects the bullet’s flight path, I modeled both cartridges using a ballistic calculator application. I assumed a 100 yard zero, scope 1.75″ above the bore, and temperature of 59F. The drop in mils is shown for 200, 400, 600, 800 and 1,000 yards. The drift for a full value 10 mile/hour cross wind is shown in mils for 200, 400, 600, 800 and 1,000 yards.
For comparison purposes, I included data for a 308 Winchester (308/22″/175SMK), 300 Winchester Magnum (300/24″/190 SMK), 6.5 Creedmoor (6.5/22″/142SMK), 223 Remington (223/20″/69SMK) and 223 Ackley Improved (223AI/24″/80SMK). The 308 Winchester data is taken from my 22″ 308 Winchester match rifle using 175 SMKs. The load has a velocity of 2670 feet/second, hotter than the published velocities for M118LR in use by the US Military. The 300 Winchester Magnum data was obtained using Federal 190 grain Gold Medal ammunition in a 24.25″ Shilen barrel with the observed muzzle velocity of 2892 feet/second. Federal advertises the load at 2900 feet/second. The other data are from loads developed in rifles that I own. The comparative data are shown in the last five lines of the tables below.
224 Valkyrie fight!
In this section, lets looks at how we can model the 224 Valkyrie against these selected loads. Please note, the presumption here is you don’t need the payload to kill a bull Moose at 300 yards.
224 Valkyrie versus 308 Winchester with the 175 SMK
Note the 224 Valkyrie is a strong performer when compared to the 308 Winchester with the 175 SMK in the 17″ barrel, shooting flatter with the same drift. It also has far less recoil and can fit in a standard rifle. If you only shoot targets, seems like the winner.
224 Valkyrie versus 300 Winchester Magnum with the 190 SMK
While it doesn’t shoot as flat as the 300 Winchester Magnum with the 190 SMK, it happens to be way smaller. Sorry little Valkyrie, the big guy wins.
224 Valkyrie versus 6.5 Creedmoor with the 142 SMK
Again, the Valkyrie can’t hang with the Creedmoor; however, in gas guns, the Creedmoor requires an AR-10 sized platform. If you simply want a lighter recoiling rifle that you can simply swap uppers with on your MSR 15, the 224 Valkyrie still seems like a good idea.
224 Valkyrie versus 223 Remington with the 69 SMK
There are many different loads to race it against, but I decided to do with the tried and true 69 SMK. It isn’t even close, the Valkyrie slays it with the 90 SMK.
224 Valkyrie versus 223 Remington Ackley Improved with the 80 SMK
When I started reading about the 224 Valkyrie I thought it sounded similar in performance to the 223 AI. Unfortunately, I haven’t shot the same bullets in both for a better comparison. With this limitation in mind I took some of my data for a 24″ 223 AI with an 80 SMK from a 24″ tube to “race” against the Valkyrie. The 223AI.80SMK shoots flatter than all the Valkyrie barrel lengths with the 90, however, the Valkyrie drifts less. This is clearly the result of the superior performance of the 90SMK. This also shows the true advantage of the Valkyrie. While I could chamber a 223AI in a gas gun, I wouldn’t be able to feed the 90SMK loads from a magazine that fit inside of the rifle. This is the genius of the Valkyrie going with a shorter and fatter case, it can still feed the heavies.
What are your sources of error? In this experiment I controlled for the barrel, chamber, and temperature; however, I did shoot a fairly small sample size of only 5 rounds at each interval for the 90SP, 90SMK, and 60 NBT. I fired 4 rounds at each barrel length for the 75 TMJ. You can scroll down to the end of this post for a complete discussion about how samples size can influence results.
Do you think using a new barrel was an issue? That is a frequent question that I typically get with these posts. To test whether or not it was valid I did conduct one test in A look at how rifle barrels speed up: Measuring the increase of muzzle velocity in new barrels. I think if you take a look at it you’ll see a new barrel speeding up would have minimal effect on the results.
Did you shoot any groups? Yes. I did. More on that below. But, if you can’t wait, crowns don’t matter a whole lot and 90 grain .224 bullets don’t stabilize in a 1:9″ twist barrel.
Do crowns matter? This is an interesting question. The answer is they seem to matter less than you think, which is counter intuitive. Take a look at this crown below:
Doesn’t look like much does it? This is how a barrel leaves the factory from Shilen. You’ll note the end is cut with a band mill and there is a 60 degree center cut to mount the barrel between centers. So how do you think it shot?
Here is 5 rounds of the Federal 60 gr NBT at 100 yards. .575″ (.549 MOA)! That’s great for any factory ammunition.
So, how do you think this one did? Pretty rough huh?
Five rounds at 100 yards measuring center to center .439″ (.419 MOA)! Boom!
If you are a regular reader you’ll note my target looks different. I used to use 1″ orange dots on cardboard targets. They worked in most conditions, however, in heavy rain or extreme cold, the adhesive would fail and they would fall off the target (see the orange dots in the target above). I developed this target with Rite in the Rain. It is on waterproof stock with true 1.047 MOA green dots. The color provides excellent contrast and you can still see your impacts on the paper. Rite in the Rain sells these targets as well as paper that you can print your own targets on. To learn more about Rite in the Rain and their line of targets, click here.
How’d your DEWALT cordless cut-off tool work? With the 60 Volt batteries, I could make 10 passes through a stainless steel barrel on a charge, so that part worked well. It covered everything in abrasive dust that needed to be removed and it melted my Arc’Teryx jacket. Not so happy about that. I consider it a life lesson, much like the time I learned that welding in sandals was a bad idea.
What are your thoughts on the Valkyrie? I think it has a lot of potential in both gas and bolt guns. I’d like to see more Remington 700 and Howa 1500 actions available with an SPC bolt face to make builds a little easier. Until then, the bolt gun guys will either be re-cutting bolt faces or ordering PTG bolts. Sierra recently introduced a .224″ 95 gr SMK, I’d love to get that in one!