New Benjamin 397 Shotgun

[Methuselah]

Pellets get hung during loading even with the barrel pointed up.

[splitbeing]

Now if only all ten fired like that at the same time...

[Back_Roads]

 Were these known to have paint overspray in the muzzle, clean with some sort of paint thinner

[longhunter]

Point the muzzle down, so the pellet can find it's own way into the breech. I have several guns that require this method of loading,  including my bluestreak.
Also, as Back_Roads said, check the muzzle for paint.

[Hack21]

I am intrigued about that front sight. 

As mentioned, paint in the muzzle needs to be removed if it hasn't already. 

My 392s also had a right angle transitions to the rifling that would scar pellets.  The transfer port may intersect the free bore and the rifling, making this even worse.  This can be remedied with fine sandpaper held by a partially split bamboo skewer or wood dowel that is spun in a drill.  This transition can then be polished afterwards with Brownells non embedding polishing compound. 

[Methuselah]

They were indeed the ones with paint overstay, but I tend to think it's probably "made it's through it" by now if that were the case. Tom Gaylord did one long writeup on these and in the end removed that paint with no change in accuracy.

I'll try pointing down to see if it loads easier...

I've also read the inner lug to the stock screw can be loose and cause this, and yes, sanding that transition is also.

Great suggestions all, been working on another recent acquisition today ... fixed a Daisy 747 by hand stoning the valve seat with a dremel abrasive grinding cone. The 397 is definitely next, I'm very interested in seeing if I can get it to shoot better than minute of barn!

[Methuselah]

Up to 3 distinct "steps" pointing up, two pointing down.

I've read when this happens hard round nosed pellets have the best chance of grouping. Also, after working on the leade it's much more likely it will shoot better with more pellet types. Of course not everything you read is going to work.

Next step inspection and perhaps barrel cleaning. This is one instance I wish I owned a borescope...

[Methuselah]

Norma 9.1 gr golden trophy it's seem to load holding downwards.

Too late to try for a group though, gets dark quickly, especially when it's overcast...

One pump didn't seem to hold, two did.

Are there "worthy" rebuild kits? I read adding a spring in the valve makes pumping easier.

[Hack21]

Are there "worthy" rebuild kits? I read adding a spring in the valve makes pumping easier.

Cast urethane 70 durometer orings from The O'ring Store are great.  You can use 90 durometer on the orings that are on the exterior of the valve if desired.  I am a fan of using a discovery poppet valve.  Mac1 has/had billet pump arms and adjustable pistons if you really want to make some upgrades - his website is down so you would need to try your luck with a phone call.  I would consider "packing" the valve to reduce its volume if you are interested in making enhancements. 

This is a 392 thread, but it might give you some ideas. 

https://www.gatewaytoairguns.org/GTA/index.php?topic=180192.msg156045776#msg156045776