Umarex M29 Schematic (pellet)

Yeah I noticed that. I think hope the pellet version might come with a longer barrel though. 
It's alright for you, you've got your own barrel maker. 

Mechanically they're the same as the S&W-629s (valve, shells & barrel) and I found that the accuracy was better than average with just the smoothbore barrel fitted and firing pellets, the only thing was it seemed to lack a bit of 'oomph' (averaging in the low 300 fps). I would advocate increasing the size of the ports in the valve stem slightly with a dremmel and a diamond tipped drill bit, I managed to get mine up to the 380-390 fps mark now with the 6½" and 390-400 fps with the 5", but I did go at it a little more with the 5" to try to make up for any barrel length deficit, might have gone a bit OTT with it, lol.

The valve itself is a good quality item, generally what we've come to expect from the manufacturer Wingun (DW715, Schofield, Webley mkVI, etc.) and as such they always benefit from a little tinkering without the danger of destroying it, unlike the KWC valves (like the shell loading Colt Python that they made for Umarex a few years back) which have a tendency to fail if you go too far with any modifications to them.

Although chasing higher fps performance is not something that we (as replica owners) really want or need, it does go a long way for that POA vs POI consistency and plus, for getting tin cans to really dance around the back yard like a pinball, it's an absolute must, lol.