Benjamin 397P Phase 1

[ratbuster2240]

I need to say a big thank you to member -Ped-, he is one of our airgunbbs legends and without his knowledge on these old guns I would have had a hard time importing parts from the US especially during this pandemic.
My go to garden plinker has been my Crosman Backpacker/1322, ideal for my small garden where power can be varied. I have spent 15 years tinkering with this gun and it’s given me a lot of enjoyment, so I thought I’d look out for a full length Benjamin, Sheridan or Crosman pumper.

I didn’t have much luck with my search, ideally I wanted a Crosman C9a which has a cartridge valve type they don’t require a special tool and are easier to re-seal. These are also available in the more popular .177 and .22 calibres, although now the variety of .20 pellets are pretty good. Eventually I found this one on Guntrader for £80, not quite what I was after with the soldered in valve but I was happy when I received it as the quality feels more like an older Sheridan Blue streak than the new Crosman’s with lots of plastic parts.

It’s a Benjamin 397P made in USA, Racine, Wisconsin which is the old Sheridan factory before Crosman moved production in the 1990’s. From what I have researched this model was made between 1991-1993. The serial number begins with the letter I which is probably 1991. This means it was made by Benjamin Sheridan before Crosman bought them out in 1992.
It is in quite good condition, there is no barrel separation where its soldered to the tube but it does have a few marks on the stock and wear on the receiver from where the hand is meant to grasp during pumping. I quite like this wear has it reveals the bronze metalwork. Mechanically it was okay and it held air but I noticed it would take 3 shots to expel all the air, so I thought I’d open it up and see what may need refreshing. Some owners of the old 1960’s Sheridan's have never even had to re-seals theirs, so they can last a long time.

The hammer was very gunked up with solidified grease which was probably slowing the hammer so I cleaned it out and polished up the surfaces, spring and guide. It already had the Sheridan type inlet seal carrier but the rubber seal was flattened so I put the polyurethane seal on from Ped’s kit. Surprisingly, the pump cup seal was intact, but I replaced it anyway. It was very dirty inside the pump tube with old grease and probably sucked in contaminants, so I spent a lot of time cleaning it out, carburettor cleaner and 12bore cleaning rods were particularly good for this.

The valve was heavily oxidised which apparently occurs if it’s not shot for a long time, the previous owner said it was always stored with one pump of air, but I don’t think it was properly lubricated. The valve rubber seal was again very squashed, this indentation can make it harder for the valve to move off the seal face so I replaced it with a new Benjamin Discovery valve, a Crosman King Ratcatcher also works. The old lead seals were replaced with synthetic which is easier to fit the only other seal needing replacement was a bolt probe seal. When the bolts beds in, you can adjust the lug, this one was quite loose so moving it closer to the allen head bolt helped get a tighter fit at the breech and this should give a few FPS increase.

The trigger is very basic it was quite gritty and odd to pull so I polished up the sear and greased the contact points and it feels much smoother. I spent a considerable amount of time cleaning and polishing internals before re-assembly. Ped made me up some new soldi pivot pins with e clips, so I don’t have to bash in any roll pins and these fitted perfectly.
It seems to be holding air fine and its dumping all its air after 2 shots instead of 3, after more research it seems the UK variants had their hammer springs cut to keep the power within the legal limits. I have a new full length spring but to be safe I’ll leave the old one in until I have chronographed it.

I put 4 pumps in tonight and at 15 yards standing I shot a nice cluster with just some Gamo pellets and I was amazed that the sights were spot on. I am looking forward to testing the accuracy, I think its going to be a very accurate rifle.
I’ve added some felt furniture pads to quieten the clapping pump arm but at least the neighbours just think I’m in the garden clapping for NHS workers. I have ordered some Benjamin barrel mounts, I may just put small red dot on to test the accuracy. I have noticed this model is also pre-tapped to fit a Williams peep sight, which means I can remove the original rear sight, which can be a culprit for barrel separation.