Sunday, January 11, 2015
Benjamin Trail Nitro Piston Pistol--Part 2
Revisited the plunger spring. Went another coil longer.
60% moly grease on the plunger.
The stock plastic bushings were really close to 1/16" thick. I went hunting and sourced these 3/8" x 5/8" x 1/16" thick bronze thrust bearings. They came from the local Ace Hardware store. They were in the Hillman fastener section. Hillman #58008-B. Don't remember exactly what they cost, certainly less than a buck each.
These will probably be just dandy, though ideally there would be more surface area against the breech block.
So I kept looking. McMaster-Carr part #5906K531. 1/4" x 5/8" x 1/16" ran me all of about 96 cents each. They'll need drilled out for the pivot bolt.
A letter J drill bit is about 0.003" larger than the bolt diameter. while this did work, a slightly larger drill bit would've made it substantially easier to install the pivot bolt. Lining up the bronze washers was a real trick with so little clearance.
Still have room to go larger in OD to fit the counterbore, but I've run out of easy to find commercial offerings. This'll do.
Put it all back together and shot I forget how many pellets at the target--twelve or thereabouts. Better than the last target, but I don't know how much to attribute to the thrust bearings. This pistol doesn't exactly lend itself to being "benched" for accuracy. It does feel better now when snapped shut after loading. More solid, substantial. The biggest improvement came from fixing the plunger spring to improve the breech lockup. I think it's a pretty good shooter now for around $75 and I have the novelty of a pistol with a gas strut. For the money, I still find that the CO2 powered Crosman 2240 has more going for it--more potential accuracy as well as a huge cult following and aftermarket component upgrades.