Well, it has been a lovely long weekend with a good blend of family and shop time.
I'll open by saying I did not follow my original plan of trying a plain MDS nylon hammer. But I'll get back to that in a moment. First I'd like to touch on the barrel porting. The factory porting consists of a groove with 2 drilled holes:
Since the barrel threads into the receiver, this arrangement is good for manufacturability because the factory does not have to be concerned with where the ports end up in relation to the valve's exhaust. In my particular case, the two ports unfortunately ended up at 3 and 9 o'clock, maximizing the distance and sharp turns the air must take to reach the pellet. So I drilled a 3rd hole in line with the valve and tried running it like that for a few days, but I knew the better approach would be to fill the groove with epoxy and mill a single large-ish port in line with the valve's exhaust:
Without touching the hammer spring tension, this change yielded a 6% increase (110fpe -> 117fpe), in spite of the fact the new single port is smaller than the combined area of the 3 round ports.
Now back to the lightweight hammer and PEEK poppet. So why did I decide against trying a 100% plastic hammer? Well, I removed the OEM hammer and put it on the scale:
Yikes. No way going from a Delrin poppet to PEEK is going to make it that easy to knock open. So I decided to just go ahead and make a 2-piece hammer with a steel core and MDS nylon body, and target a weight somewhere in the ballpark of a third of the original.
And, oh look, an offcut from a .177 Crosman barrel weighs about 24 grams:
Drilling and turning the nylon body:
The finished 2-piece hammer weighs 33.6 grams, or about 31% of the OEM hammer:
Then I turned a new poppet and selected a weaker valve spring (bottom) to replace the originals (top):
Then I reassembled and tried test firing it with no changes to the hammer spring preload. The new velocity?
0 fps. Haha, it barely blipped the valve, the pellet didn't move, and I could hear just a tiny psssssssshhh of air bleed out of the breech over the course of a few seconds. Okay I'm going to need some more hammer spring so I rummaged through my Cool Whip container of springs. Every spring even remotely close to the right gauge and diameter was too short, but I'm too impatient to wait to get some springs in so I picked out a couple and turned a little plastic coupler to join them end to end:
Reassembled into the SSG:
Ah, there we go:
258mps (846fps) with an 82.2gr pellet for 130.6fpe. That's up on the velocity plateau so I need to back it off a little, but even with it wasting air, the muzzle report is already noticeably less boomy so I'm happy with how it's going.