6.5 Creedmoor- Effects of Barrel Length on Velocity 2019

“We do it right because we do it twice!”
Greg Wagner, Wildlife Photographer

Background

The 6.5 Creedmoor has become one of the most popular center-fire cartridges in the precision rifle world. Not only does the cartridge balance impressive ballistic performance with a relatively low recoil impulse, it cycles well in both bolt-action and semi-automatic rifles. Whether you want to plink at steel, enter a precision rifle match, or hunt medium size game; the 6.5 Creedmoor will do the job, and do it well!

As a gun writer it is often hard to predict which posts will be popular and which won’t. Sometimes you get it right, sometimes you get it wrong. Other times you write something that doesn’t seem particularly intriguing but it takes off. My original 6.5 Creedmoor barrel length post, 6.5 Creedmoor- Effect of Barrel Length on Velocity: Cutting up a Creedmoor, is a great example of that. I was curious and did a relatively quick test. I assumed shooters would read it but I didn’t think it would have the success that it did.

While I stand behind the findings of all my posts, 6.5 Creedmoor- Effect of Barrel Length on Velocity: Cutting up a Creedmoor! had a few apparent flaws to my readers. Many pointed out that I, (1) used a new barrel, (2) used an inexpensive barrel, and (3) shot only two different kinds of ammunition. In the 3 years since I published that post, I decided that the readers were right. Time for a do over. Or, as my friend Greg says, “we do it right because we do it twice”.

For the updated barrel length post I had originally intended on using a new Bartlein Heavy varmint barrel. This would allow me to provide a data set from 31″ down to 16 or 17″. This was the first direction I had planned on going in but when I grabbed my 6.5 Creedmoor text rifle to re-barrel, I figured I had a better idea. I’d just chop up the barrel on the rifle I’ve been shooting lately. This would give us a data set from 26″ down to 17″ in one inch increments, these would be the most likely barrel lengths the majority of shooters would use.

I reached out to long time rifleshooter.com supporter Brownells, and ordered 5 different kinds of factory ammunition in addition to one 142 grain SMK hand load. This would provide a larger set of data amongst the most popular factory offerings available to shooters.

The test loads are:

Hornady 147 ELD Match (factory load)
Sierra 142 MatchKing, 41.5 gr H4350, CCI 200, Staline Brass (hand load)- warning, considered safe in test rifle only, consult load manual for more information
Hornady American Gunner 140 grain (factory load)
Norma 130 grain HPBT (factory load)
Hornady American Whitetail 129 grain InterLock (factory load)
Federal American Eagle 120 grain OTM (factory load)

Testing protocol

My test gun is a factory Remington 700 that I built at my shop, 782guns.com.

I built it with parts from Brownells, including:

The barreled action was placed in an MDT ESS chassis that is equipped with a carbon fiber forearm and a folding stock (one of my favorite!).

At the beginning of the test, this Proof barrel had 1,085 rounds down the tube. The prior use of this barrel would eliminate concerns that the data set was somehow compromised because I used a new barrel.

For each load and barrel length combination, I decided to fire five-round strings and record the muzzle velocity with a MagnetoSpeed V3 barrel mounted ballistic chronograph. After I gathered the data for all six test loads at a given barrel length, I’d use a cordless circular saw to remove 1″ from the length of the barrel and repeat the test.

I had the misfortune of melting one of my MagnetoSpeed’s when I mounted it directly to a suppressor, so I reached out to MK Machining for one of their MagnetoSpeed rifle mounts. These mounts attach the chronograph to the picatinny rail of the rifle and work extremely well.

This test controls for barrel and ambient temperature (45F). I shoot at sea level with the water to my back. If some of the speeds you get with similar equipment look slower, it may be because you are shooting at higher elevation or temperature, both of which will affect results.

Results

Results by cartridge

Hornady 147 ELD Match, effect of barrel length on velocity

Muzzle velocities for the Hornady 147 ELD Match ranged from 2,728 ft/sec to 2,492 ft/sec, with an overall decrease in muzzle velocities of 236 ft/sec when the barrel was shortened from 26 to 17 inches. Reduction in muzzle velocities per inch ranged from a gain of 1 ft/sec to a decrease of 40 ft/sec. Average velocity loss per inch of barrel was 26 ft/sec.

Sierra 142 MatchKing handload, effect of barrel length on velocity

Muzzle velocities for the Sierra 142 gr MatchKing ranged from 2,771 ft/sec to 2,584 ft/sec, with an overall decrease in muzzle velocities of 187 ft/sec when the barrel was shortened from 26 to 17 inches. Reduction in muzzle velocities per inch ranged from a gain of 5 ft/sec to a decrease of 40 ft/sec. Average velocity loss per inch of barrel was 21 ft/sec.

Hornady 140 grain American Gunner, effect of barrel length on velocity

Muzzle velocities for the Hornady 140 grain American Gunner ranged from 2,693 ft/sec to 2,491 ft/sec, with an overall decrease in muzzle velocities of 202 ft/sec when the barrel was shortened from 26 to 17 inches. Reduction in muzzle velocities per inch ranged from a loss of 15 ft/sec to 37 ft/sec. Average velocity loss per inch of barrel was 22 ft/sec.

Norma 130 grain HPBT, effect of barrel length on velocity

Muzzle velocities for the Norma 130 grain HPBT ranged from 2,859 ft/sec to 2,651 ft/sec, with an overall decrease in muzzle velocities of 208 ft/sec when the barrel was shortened from 26 to 17 inches. Reduction in muzzle velocities per inch ranged from a gain of 7 ft/sec to loss of 58 ft/sec. Average velocity loss per inch of barrel was 23 ft/sec.

Hornady American Whitetail 129 InterLock, effect of barrel length on velocity

Muzzle velocities for the Hornady American Whitetail 129 InterLock ranged from 2,845 ft/sec to 2,642 ft/sec, with an overall decrease in muzzle velocities of 203 ft/sec when the barrel was shortened from 26 to 17 inches. Reduction in muzzle velocities per inch ranged from a loss of 7 ft/sec to 37 ft/sec. Average velocity loss per inch of barrel was 23 ft/sec.

Federal American Eagle 120 OTM, effect of barrel length on velocity

Muzzle velocities for the Federal American Eagle 120 OTM ranged from 2,885 ft/sec to 2,643 ft/sec, with an overall decrease in muzzle velocities of 242 ft/sec when the barrel was shortened from 26 to 17 inches. Reduction in muzzle velocities per inch ranged from a loss of 10 ft/sec to 42 ft/sec. Average velocity loss per inch of barrel was 27 ft/sec.

Effect of barrel length on Standard Deviation

Since Standard Deviation is always a topic with the precision rifle crowd, I went ahead and created a table (above) and plotted it on a graph (below).

While you may find this information is informative as far as ammunition selection and standard deviation, you don’t see as much of a benefit in terms of standard deviation in any particular barrel length.

Closing

I’m presenting this post as raw data. I’ll be posting subsequent posts on conclusions we can draw from it. In the interim, I’d suggest reading my original 6.5 Creedmoor barrel length post 6.5 Creedmoor- Effect of Barrel Length on Velocity: Cutting up a Creedmoor!; there is a lengthy discussion about the real world impact barrel length and muzzle velocity have.

I reach nearly two million unique readers a year on rifleshooter.com. The content I publish on the site requires a lot of hard work and some fairly expensive resources. I wouldn’t be able to bring content like this to you without the support of our sponsors. I want to thank Brownells, MDT, Starline Brass, Timney Triggers and MK Machining for helping make this post, and rifleshooter.com possible.