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. 


nowhere said...

You actually got this gun to group respectably well! I really had no hope for the design based upon experience and various reviews. Well done! I agree with you that this pistol isn't too impressive compared to a 2240. I'm biased in favor of spring and pneumatic guns because I like the idea that it's my own stored muscle power sending the pellet downrange instead of the gas in an expendable cartridge but even I would go for a 2240 over this.

derrick38 said...

I just rested the butt of the grip on a shelving unit and tried to use consistent grip pressure. You'll probably get better groups than I did, especially if you have any experience benching pistols.

I read all the bad reviews, too and pretty much ignored them.

Harry said...

I'm going to be doing an airgun project for my blog starting with a Crossman 1088 which has been fully disassembled. I wasn't sure if these even go back together but setting your projects make me think it is possible lol. Hoping maybe I could email you if I get myself in big trouble.