Range Report - 6.5 Grendel PDW 7.5 Inch Barrel

[depletedyourcranium]

Here's my quick range report on my PDW-Grendel build from the other thread. I decided to do a new thread since that last one was getting side tracked by a yet another caliber war... Anyway, over the weekend I was able to do some initial testing of the barrel and got some chronograph data with a couple of loads. Although the total barrel is 8.5 inches, I'm going to refer to it as a 7.5 inch barrel from here on out since that's the actual length from the breech to the end rifling surface and most accurately describes it's performance, that way no one is going to confuse these velocities with a proper 8.5 inch barrel... if anyone ever goes that route. Here's a pic of the setup to give you an idea on just how short the overall package is:


16.25 inches folded


24.5 inches to the first brace position. 26.5 inches with the brace fully extended.

Now, onto the data. All shooting was done from the prone, bag supported on the rail, chronograph positioned about 10 feet from the muzzle. Chrono was a Caldwell Ballistic Precision with the wings installed. Temps were about 50°F, elevation about 1400 above msl. No idea on pressure or humidity or anything like that.

Hornady Black 123 grain ELD-M:
1917
1914
1917
1890
1919

Mean Velocity: 1911 fps
SD: 15.09

Hornady American Gunner 123 grain HPBT
1868
1910
1909
1911
1849

Mean Velocity: 1889 fps
SD: 29.00

Wolf Military Classic 100 grain FMJBT
2090
2162
2113
2141
2182

Mean Velocity: 2138 fps
SD: 33.01

Another note on the Wolf load, I did some more shooting through the chrono later and the Wolf seemed to either measure right around 2050 or 2150 and not much in between. Goes to the general QC issues we've all learned to expect from the steel case imports.

So anyway, as far as these numbers it tells me that 7.5 inches is the absolute shortest I would consider going in 6.5 Grendel. I was expecting pretty low velocities but hoping for maybe 100 fps faster than what I was getting. Perhaps a 5r rifled barrel could have got these up another 50 fps. For my purposes with this gun and what I got the barrel for, I'm still likely within a level of terminal effectiveness and range I'm satisfied with for such a small package... but just barely. Essentially it's the same power level of an M1 carbine at the muzzle and will carry a little more energy downrange than one. Considering this was replacing a 9mm PCC in this role, for me it's nice step up in power and moderate increase in range at the cost of a little weight and lots of noise/flash. Speaking of muzzle blast, which is pretty difficult to objectively quantify... so far it wasn't as bad as I was expecting. I wasn't getting that teeth jarring concussion that you typically get with something like a 5.56 pistol and it seemed comparable to shooting my 12 inch Grendel, though I didn't shoot it that day. I did notice the blast a lot more in prone, there was significant kick up of debris but, again, I didn't shoot my 12 that day to compare. The only time I noticed significant flash in my sight picture was with the Hornady Black ELD-M, and it was huuuge. I was shooting outdoors in the daylight but I was in the shadow of the hill around 1800 local, so it was a little dim all around. The Hornady AG and the Wolf MC did not have that effect and the flash went pretty much unnoticed. Here's the best image I could get of the flash from a video clip of me shooting. I'd say, at least with the Wolf MC I was shooting in the vid, it was pretty comparable to the 12 inch: