Some locking bolt springs are a little "large", i.e. they are too tall when installed and the bolt won't slide in.
Last 2 I installed had to be ground down slighty, very slightly on the top of the "L", the part you can see when the spring is installed in its slot.
Just a little!
it is not very thick. I used a small stone on a dremel tool; springs are hard so they won't cut with a file, if they do they are not good springs! Hold the spring by the short leg in a pair of vice grips.