Air Gun Home :: View topic - My new B-4 177 cal.

Gunrunner · Member

Finished this one little late but its has to be the sweetest one I built yet.
Chopped the piston and added my custom seal which gave me an extra .885 in. of sweep, removed the bear trap and cut the trigger housing back to where the bear trap engaged in order for it to cock. Sanded and smoothed down the sear and trigger along with the catch on the piston, made the port smaller 5/32 in. Re did the cocking arm pivots, spaced them with brass tubing, so it took up the play from side to side. Did it in a light mahogany and then a couple of coats of minwax poly.
The good news its pushing 842 fps in 177 cal. and like most other B-4's its places the pellets where you aim. I have just a couple of things left to do, remove the front and rear sites, grind off the rear site housing and add a weaver scope rail.
These B-4 have to be one of my favorite gun's, for the price and time, there hard to beat

Gunrunner

Here's the other Qb-78 22cal. done in a cherry stain with a much heavier hammer and hammer spring, most I had it up to was 1074 fps.

AirGunEric · Site Admin

Quick question for you- how do you install a scope rail on a B-4? You machine the appropriate piece and then what- epoxy it? Rivet it? Weld it? Screw it down?

Gunrunner · Member

I drill it out at the back where the scope rail and the C clamp join, tap it and screw it down and little sealall , it doesn't move.
Then with a rotary tool 2 little slots at the back of the rail and put a small piece of metal across the rail which keeps the scope from moving back, by the way thats a Fitco scope 6x24x44 mildot.

Gunrunner Cool