Need help, sometimes the **** falls and I gets sparks. Other time the flint gets stuck half way on the hammer face.
Do I need new spring?
So....how many shots do you get out of a flint before you have to knap it? One? two? Sounds to me like you have the angle of your flint striking your frizzen set wrong and instead of slicing along the face, it's hitting the frizzen head on. Your flint is not supposed to hit at the top of the frizzen, so don't expect it to. With most flintlocks, it hits somewhere near the middle of the frizzen or slightly above or below that point. With both of my two longrifles it strikes about half way down the frizzen (hammer).
Sure, you may have a weak spring, as I would expect it to smash the tip or break the flint instead of just get stuck, but before you buy and replace the spring (don't forget to buy a spring vise if you opt to replace the spring), why don't you try to adjust the angle that your flint first impacts the frizzen and see if that's the culprit?
To do that, hold onto the ****, pull the trigger, and slowly lower the **** until the flint contacts the frizzen. That will show you the angle that the flint is striking the frizzen. Now of course the frizzen is curved but that's OK. Just hold your rifle level; check where the flint contacts the frzzen and imagine a line coming straight up from that point at 90°. You want to get your flint to hit at 55° to 60° for the best sparks and longest flint life
If your flint hits it at a lower angle, say 45°, you'll quickly smash the tip of the flint and within a few shots have to knap the flint back into shape. If you have the flint strike at a steeper angle, say 75°, that will basically slap the top of the flint against the frizzen instead of scraping along the face and it will knock a chunk of your flint off the bottom side of your flint.
So it's really a Goldilocks effect. Too low an angle and you'll get few sparks and smash the tip of your flint. Too high of an angle and you'll start slapping chunks off the bottom of your flint. 55° to 60° is "JUST RIGHT" for most locks and you'll not only get great sparks and crazy long flint-life out of it, that angle causes the flint to be self knapping too so you rarely, if ever, need to sharpen it. When you find the right spot, you will easily get 100-shots or more out of a flint before you have to replace it.
So do whatever you have to do to get that 55° to 60° angle on your flint before you try to get a stronger spring. Move the flint forwards or backwards to adjust the contact point to get that 55° to 60° angle. Put it bevel up or bevel down, whichever it takes to get that angle. If you have to move it forward and it keeps slipping back, put a twig (or a toothpick) behind the flint to keep it from moving back. If you've moved it as far back as you can because the leather flint wrap is butting up against the **** screw and it's still too low of an angle, take the leather out; bend it in half; and cut a V-shaped notch in the middle of the fold. Then wrap it around the flint and with that hole on the back edge and you'll find you can push it a little farther back than you could before.
If you get your flint position set so it strikes that position and you still are having it stick, then maybe it is your spring after all. But those springs are usually thick and very stiff. The spring that holds the frizzen in place those is usually very thin and pretty weak. All the frizzen spring needs to do is keep the frizzen from re bounding back upon firing and hitting the flint. In fact it's not needed at all to fire successfully but it is key to keep the frizzen from bouncing back and breaking your flint. So it can be a pretty weak spring.
Hope this helps.