Shown top is a production Emerson HD7 mangled at the point most all frame locks fail when stressed, (if they are built right) showing what happens when one gets stressed to the point that something has to give. There is a large variance from company to company and from knife to knife in location of the lock cuts and how they are done but one thing they all have in common is that they are taken down pretty thin at the lock relief where we makers bend the lock to put spring in it. Many people question why and have written me asking for comment on this over the years. Pieced together below are copy and pastes from many of those answers which is part of why there are different print sizes from different forums formats.. Anyway, the reasons for lock cuts are worth review. One could say that this aspect of the frame lock is sort of a controlled burn, so to speak. Being a field tester for several cutlery manufacturers at times I have had some pretty neat experiences from various testings I was asked to do on various models either already being produced or being considered for production sent to me as a proto-type to give feed back on first. Please note I don't mean to imply that Emerson was one of these companies by showing this photo. EKI is one I have not tested for but as you can see looking around my blog or forums I'm certainly familiar with them. This photo simply demonstrates my point quite well. For those companies I have consulted with some models make it to production based on feedback from various field testers like myself, selected for whatever reasons by some of those behind the scenes folks that keep coming up with all these fine new knives for us nuts! At other times testers catch things missed that are corrected before it is produced and made available to the public.
Being that I make replacement customized pocket clips this puts me in a unique position in the industry to hear about this from users I guess as this would be why they contacted me and that is just how I discovered this about the lock cuts even being reported to cause folks to drop their knives at times by holding onto the pocket so firmly from these lock cut snags.. I say it is my opinion because my sampling of the industry is small and it is debatable if it a true representation of the larger portions of knife owners but it is likely there are others out there that have noticed this and never said anything. I say it again just for the record, that's my opinion.
In some cases unless you pull the clip stem at the lip getting it up off the folder to reset the clip tension setting to make it grab pockets less this snagging is enough to make one complain about it and even cause them to drop their knives when trying to pull them out to use them. I've had emails over this from users and heard the complaints and had the questions from users over the years asking me to either take down/reshape lock cuts on knives they own or replace/relocate clips etc etc. This question about fixing this issue does come up with lock cuts on the outside. To date I've had this question over the Strider PT the most. I've had others once or twice and several custom knives with deep lock cuts have been sent to me for clips utlizing the pre-existing holes since I refuse to modify anything custom or even work on it when the maker is still around.
I can tell you that these beefy super thick models with even deeper more profound lock cuts with squared off deep side wall edges and a clip sitting right over that cavern is a snag waiting to happen lets put it it that way. I'm always puzzled by this and I see plenty of frame locks I like other than the lock cuts being out instead of in. If and when new makers ask me I tell them quite clearly if it were me, knowing what I know now I'd never do a lock cut on the outside on any frame lock and if I did it would always be done with sweeping half moon shapes tapering gently as opposed to deep sudden squared off cuts, particularly if there is a pocket clip mounted nearby that cavern. These type of cavernous squared off lock cuts are the ones usually responsible for customer complaints to me when they want to know if I can build a new clip to sit cocked such that it is away from that cavern hole lock cut or reshape the existing lock cut so it is not such a drop off that has a distinct corner.