Tuesday, October 25, 2011

Diamondback DB9 Standard Versus Compensated Barrel Velocity Study

I was asked to evaluate the velocity difference between a standard and compensated Diamondback DB9 barrel.  Diamondback sent one to me for the test and I was told I had the option to return the barrel within a set time period or I could keep the barrel for a price that is less than retail.  Since doing the test would only cost me ammo and I was going to be breaking in a new DB9 EXO anyway, I thought I would jump on the opportunity and see how things played out.

There have been several questions about velocity gain or loss due to two characteristics of the compensated barrel.  The first is that the compensated barrel is longer than the standard.  The second is the compensated barrel has two horizontal cuts across the top to vent gases forward and up during firing to reduce muzzle flip and also recoil impulse.  Since the vents start outside the slide, the standard DB9 slide can be used with the compensated barrel.  The photo below shows two standard DB9 barrels and one compensated DB9 barrel.


Today, I tested 4 different loads through two DB9s.  The all black DB9 had the standard barrel and the DB9 EXO had the compensated barrel installed.  Both pistols are shown below with their matching Size 3 Remora pocket/IWB holsters.

The testing set up was identical to previous velocity testing work.  Those that read the blog frequently will know this set up all too well.  I run a CED M2 chronograph that's about 8 feet from the muzzle.  I shoot from a seated position.

I shot video during the testing today so you could see the results I captured just like you were there with me today.  I cut up the raw video with some title slides to insert breaks between the different tested rounds.



If you don't want to watch the video, then you can just jump to the spreadsheet below that has all the gory details.  The net results from the test showed that there is virtually zero velocity gain or loss between the standard and compensated barrels for the 4 loads tested today.

Really, I'm not surprised by this.  You would think that the longer barrel would delivery higher velocities as longer is usually better for gas expansion and building velocity, but you have to factor in that the added barrel length is also cross cut with vents that provide an escape path for those expanding gases as they enter the added barrel length.

Diamondback claims that their tests show a measurable reduction in recoil with the compensated barrel.  In addition to shooting from a bench, I also tried both barrel types from a standard standing shooting position.  I did this last week and again today.  I can confirm that there is a slight reduction in felt recoil with the compensated barrel.  I literally had to shoot one gun immediately after the other to really appreciate the reduction.

When I was asked to do this testing, I really didn't think I would end up keeping the compensated barrel.  The curious side of me definitely wanted to shake out the barrel and see how it performed, but I ultimately expected to send back the barrel at the end of testing.  What I didn't expect was an improvement in accuracy with the compensated barrel.  The target below was shot last week and got me thinking that perhaps this compensated barrel was a good fit with the new DB9 EXO.  I shot this target in a darkish indoor range and thought it might have been a fluke, but would be worth checking a second time.


Today I shot my standard DB9 (target on left) and the DB9 EXO with Compensated barrel (target on right) again with six rounds pulled from the same box of ammo.  This was RWS 115 grain FMJ that I had never shot before so I had no idea what to expect.  The compensated barrel equipped DB9 again shot a tighter group and clustered the shots more tightly around the point of aim.  These targets were placed out at the 7 yard line.   

So to wrap this up, I will be keeping the compensated barrel and it will be installed in the DB9 EXO.  I can confirm a small reduction in felt recoil with the compensated barrel and also confirm that the combination of my specific DB9 EXO and the compensated barrel I was sent for evaluation delivers better accuracy than my original standard DB9.  Velocity proved to be quite equal with the two barrels so neither a gain or loss of velocity was noted.  So, I'm buying the barrel since reducing felt recoil while improving accuracy has always been "money well spent" in my book.

2 comments:

  1. Where does one obtain a compensated.db9 barrel?

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  2. At the time this was published you could buy them from Diamondback. It looks like they've been discontinued.

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