Underwood Xtreme Defender 115gr

[chucky2]

Underwoods rep though is that they meet what's on the box (and in many cases exceed it).  If these are hitting those speeds then IMHO, they shouldn't say 1700 on the box.  If the 4.75 average is 1640 then 1650 would be a more appropriate number.

[01deuce]

Underwoods rep though is that they meet what's on the box (and in many cases exceed it).  If these are hitting those speeds then IMHO, they shouldn't say 1700 on the box.  If the 4.75 average is 1640 then 1650 would be a more appropriate number.

Maybe Underwood's test gun for these was a 6 inch barrel.

[chucky2]

I think that would be a departure from what they normally use to dictate their box speeds.  Memory serves it was either a Glock 20 (4.6" barrel in those) or a 5" 1911-type they used.  If they're basing their numbers off 6" barrel now then that is something new I believe.

[sqlbullet]

50 fps at these speeds in only a 3% variance.  That could be barrel to barrel difference.

[chucky2]

I haven't paid that close attention, but my perception was that out of the 4.75" barrel he always uses for testing, doesnt the average for the Underwood rounds tested always hit advertised velocity?  If not it's not a massive deal, I just sorta always got used to seeing people Chrono and get advertised velocity.

[Overkill338]

I just asked Underwood about what barrel is used, on November 21st. Here was their reply.

We're basing our 10mm velocities off of a 5" barrel, you should expect a loss of about 50fps using a 4.6" barrel.
For 40SW, we are using a 4.6" barrel for velocities.
From a G29 you should expect about 1100-1125fps using the heavy 200gr bullets!

Their estimate was close, Harrygunner got an average of 1143 with their 200 XTP.

[chucky2]

And now we know!  Thanks Tic-Glock!

[Intercooler]

Huh? So now they base testing on 1911 length? It was G20 4.6" forever.

[Overkill338]

I thought it was a G20 also. Because in that video on YouTube, he got better than their advertised velocities with a G20. I'm going to reply to the email and ask them if they have always used a 5" and from what distance.

Edit: Email sent.

[Intercooler]

I wonder if that is across the board as well? That troubles me, because it reminds me of Doubletap.

[Overkill338]

Here is the report back guys.

We used to use a G20 with the 4.6" stock barrel for velocity reporting, but early 2015 we switched to using a 5" in a different platform for a multitude of reasons.
We also switched in late 2015 to a Digital Doppler Chronograph, so we aren't very far from that when we shoot, those are set up to shoot with the muzzle nearly parallel to the machine, but I don't think it actually starts tracking the projectile until it is about 10 or 15 feet in front of the machine. We used to set our old chrony up about 10 feet away, and surprising enough both machines will read within 3-5fps of each other on average when we're parallel to one and shooting over the other from 10 feet, though the digital one is far more consistent and far less sensitive to weather and lighting conditions.