Not certain what barrel length Underwood.  However, one could deduce his test platforms are duty sized as in nearly every chronograph test (typically duty sized firearms) on the internet, Underwood comes in very close and not  uncommonly exceeds advertised velocity.   

As compared to Double Tap....  Who must use 9" barreled firearms as test platform to achieve their advertised velocities. 

Buffalo Bore does the absolute best in publishing the test firearm length as well as ballistics tables for various other velocities.  He provides a lot of additional information on his website.  Additionally, the owner personally responds to e-mail questions. 

Normally run 10.2-10.4 BD with the 180gr head... G20/3 with 22lb spring

When I want a hot woods round, I use the same load with a 200gr XTP with new Starline brass.
** work up to this load as it is over book and may not work the same in your gun **

Quote from: Olgo on August 05 2018 08:27:08 PM MDT
I think from the 6" barrel too.

http://www.ballisticsbytheinch.com/10mm.html

SIG 180 grain FMJ.     This stuff is advertised at 1250 fps and I believe it, as it feels like my handloads.  Not watered down stuff.   And it's quite a bit cheaper than other brands.

Yes the Sig 10mm FMJ's make their numbers and the pull-down documentations actually showed well too.
My test for velocity 4/2/2015
Glock 29   velocity     1178    case expansion    0.4315"
Glock 20   velocity     1250    case expansion    0.4315"
Glock 20   velocity     1260    case expansion    0.4315"
S&W 1006   velocity     1276    case expansion    0.4265"
S&W 1006   velocity     1286    case expansion    0.4270"

Underwood uses a 5" barrel,straight from the horses mouth

Sent from my SAMSUNG-SM-G891A using Tapatalk

Quote from: Rojo27 on August 06 2018 06:07:00 AM MDT
Not certain what barrel length Underwood.  However, one could deduce his test platforms are duty sized as in nearly every chronograph test (typically duty sized firearms) on the internet, Underwood comes in very close and not  uncommonly exceeds advertised velocity.   

As compared to Double Tap....  Who must use 9" barreled firearms as test platform to achieve their advertised velocities. 

Buffalo Bore does the absolute best in publishing the test firearm length as well as ballistics tables for various other velocities.  He provides a lot of additional information on his website.  Additionally, the owner personally responds to e-mail questions.

Underwood uses a variety of guns. But in 10mm they use 5" barrels. Justin told me this 2 years ago.