Examine the nipple.
If the top of it looks like it is bulged or mushroomed, someone probably has been dry firing the gun without realizing that beats the H out of the nipple.
If it is mushroomed the bulge can be removed with a good fine toothed metal cutting file or a whet stone.
If the nipple cone looks smooth without any deformaties check the size of the caps you are using. If they are #10, they are the wrong size.
If they are #11, the cone on the nipple is probably too large. It can be gently filed down a bit by chucking the nipple body in a electric drill. It doesn't take much material removal to make a big difference so go slowly with this.
Another thing that can cause the type of trouble you mention is if the lock is unoiled.
It's amazing the number of locks that have not been oiled sense the gun left the factory.
Remove the lock and give the inner parts a good shot of oil and then give the gun another try.
If the top of it looks like it is bulged or mushroomed, someone probably has been dry firing the gun without realizing that beats the H out of the nipple.
If it is mushroomed the bulge can be removed with a good fine toothed metal cutting file or a whet stone.
If the nipple cone looks smooth without any deformaties check the size of the caps you are using. If they are #10, they are the wrong size.
If they are #11, the cone on the nipple is probably too large. It can be gently filed down a bit by chucking the nipple body in a electric drill. It doesn't take much material removal to make a big difference so go slowly with this.
Another thing that can cause the type of trouble you mention is if the lock is unoiled.
It's amazing the number of locks that have not been oiled sense the gun left the factory.
Remove the lock and give the inner parts a good shot of oil and then give the gun another try.