If the gun won't stay cocked with a lighter trigger return spring, it has problems and is borderline unsafe.
Make and install lubed shims between receiver forks and barrel block, I usedbrass shim stock.
AKA: Snag Sear .... will near always be creepy & heavy.Reducing spring rate on the sear is unsafe Not an ideal design .. just inexpensive and simple
Make and install lubed shims between receiver forks and barrel block, I usedbrass shim stock.I don't understand how this has an effect on sear/piston engagement and the actual breaking weight of the trigger. Can you help me out here?I think he is refering to the precision part of the equation. i got one too and have been able to get it to group at 1 inch in 15 yards. cleaned the crown and polished the bore a bit. it is incredibly picky on what pellet it likes best, and i noticed that heavy pellets did better than light ones.As far as the trigger, i cleaned the sear lightly and applied a bit of dry lube (some graphite stuff). It did nothing to help the weight, but it made it more predictable (i can feel the pull to the burr that holds it until i pull it over the break. so it made it more repeatable.).mine has no scope grooves, so i cleaned up the sights to make them more effective. Love the little booger, brings you back to a more simple era this and the b3 are a joy to fiddle with.
I'm working on tuning up and improving my old B1-1 because I'm a glutton for punishment. There are two major issues I'm trying to address: precision and an atrocious trigger break. The trigger break is so bad that I can't yet tell if it's the reason for terrible 10-m groups, so I'm trying to fix it first. 10-m groups are 1.5" in diameter at absolute best.So first I scoured this board and found these threads to be the most useful:My first B1 Rifle - The darn thing works! by gloobThis thing is a piece of junk. by Rob112oShanghai B1 overhaul by CathartesTo begin, I broke the whole thing down and polished and lubed every moving part except the inside of the compression tube. The piston face got a crack epoxied (no doubt a result of some dry fires) and the cup got a good soak in leather conditioner. Next I set to work on the trigger. The trigger spring itself is fine. It's such a rudimentary design that I'm concerned that lightening it might make sear engagement inconsistent. Every few days I take everything apart and polish the sear and cocking mechanism mating surfaces with 220 grit followed by 600 grit. The sear is nice and clean, but the cocking mechanism face has a divot in it from casting that must be 0.5 mm deep. I haven't polished enough to remove it, but definitely enough to take some material off. As soon as I clean off the surfaces and reassemble everything and drop test it, I test the trigger break. The first 3-4 shots feel great, and I think "surely this time I've fixed it for good." But then within 7 shots that old familiar long, gritty, bruisingly hard trigger pull returns. I haven't measured it, but it has to be better than 7 lbs. It's bad enough that I can't do more than 20 shots before my hand and finger get too fatigued. I suspect that my final polish is still quite a bit too coarse. There's not enough clearance to get in there with a dremel tool and polishing compound, at least not what I have at my disposal. All that said, here are my questions for the moment:Should I keep progressing to finer sandpaper? 1500 grit? Diamond files, Arkansas stone, etc?orDo I just have one of the bad ones? I'm content to keep tinkering with this if a good trigger break is actually achievable, but if it's a fools errand that will just anger me and take the fun out of the hobby, it's not worth it.
This thread cost me $5.00 in pellets.My B1 cocks so smooth and easy and the trigger is so fast/predictable, it eats pellet after pellet like Pringles.
I used a diamond file until I had a nice clean engagement surface on the sear and the piston hook. The piston hook appears to be through hardened steel. Not sure about the sear. But even though the sear is just barely hanging on, it has been solid and consistent through a lot of shooting. I made these surfaces slightly crowned, rather than square. So it's like the edge of one large circle barely overlapped/hooked over the edge of another large circle. After diamond file, I used a fine ceramic stone then a buff with Dremel and chromium oxide.
The crowning of the sear is also maybe important. You don't know exactly how the sear lines up on the hook. And I think you don't want a corner of the sear to be the last part to let go.