Gunsmithing screwdrivers, including Chapman's, are designed to break before the screw head is damaged. Waste of money where I come from. The bits are scarce, expensive and not easy to get.
Any cheap screwdriver can be ground to fit and screw and work just as well.
Reminds me of a mechanic I worked with who made the claim that Harbor Freight tools are just as good as Snap-On.
There cheap tools, there are good tools, and there are the appropriate tools. You can't have all three.
I've used Harbor freight pin punches that bend or round off within a few strikes. I went to Proto and Snap-on and do not regret it.
I've seen too many cheap screwdrivers that the shank doesn't even fit tight in the handle. Junk. I've seen too many cheap bits that tear up screws rather than shear off. To you, it seems a bit that breaks when over torqued is a waste of money. But I'd rather replace a broken bit than chew up the screw and have to then drill it out. Waste of time (and money) where
I come from.
Buy once, cry once. To me, it's not worth buying HF or other junk tools, even with their lifetime warranty. It's not a matter of IF they break, but WHEN, and it's often with very little use. Cheap tools that break can be dangerous. I have scars to prove it. Had a JobSmart (available from Tractor supply, total junk) 19mm hex wrench snap... no, shatter, one the second bolt I was removing. The jagged end sliced up my hand pretty good.
If you've got to modify your tool to make it fit, and do so without a second thought, you have neither a good tool, nor the appropriate tool. Which means you have a cheap tool.
But hey, its your stuff, your money, your choice.
To address the OP:
I use a bit set by Blackhawk (the economy brand of Proto). If ever they break or wear out, I'll replace them with either another Blackhawk set, or maybe Snap-on or Blue-Point. If your guns have value, the tools you use to work on them should also have value, or your risk lowering the value of your guns. A big long idiot scratch at a screw boss or pin hole doesn't do much for resale value. And if you do that to someone else's gun, you're probably going to pay more than you would for the appropriate tool would have cost in the first place.
**I'm an industrial mechanic for a living, so I take my tools very seriously. I don't mean to insult or offend with my opinions, but I'm not going to allow bad advice to go unchecked.**