I own 2 of these sweetheart’s, one .177, and a .22. Both have been modded, The .177 came out greater than expected,I 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 860 fps w/ 10.5gr. Crosman Ultra-Mag’s, and over 1000fps w/ 5.2gr. Daisy L/F Field Point’s/RWS HVP’s, 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’s have to be one of my favorite gun’s, for the price and time, there hard to beat.
I didn’t do near as much work on my .22, but it still pushes a 14.3 Crosman Field Point out of the barrel @ 625fps, and an 11gr. RWS HVP(Skenco)at just under 800fps which is Great in my book’s, It’s extremely accurate upward’s of 30yd’s, and has dropped quite a few “Jack’s” dead in their track’s. I must say that with both of these gun’s, that the ammo you choose is very important. The .177’s a Tacker to 40yd’s, The .177 just loves Remington Field Point’s, while the .22’s favourite round is the Diabolo Straton made by CZ Kovohute, which is a little too soft for my liking, but they’ll drop a rabbit just as good as any other ammo, just with more head-shot’s connecting.These gun’s are scoffed at by a lot of people, but as with all “Chinese” hardware a little T.L.C. goes an awful long way. Cheer’s, and Happy Huntin’, Andy.