Very few people understand production, and gunsmiths are some of the worst at production because if you really want to turn out perfect work (as close as possible) you have to perfect your entire production system which is extremely difficult to do and expensive most times (how I make my $$ during the day). Not understanding production leads to inefficiencies everywhere, even guys that have their systems pretty tight have small inefficiencies that cost them hours per month and maybe even weeks per year. What we want as customers is perfection and we want it ASAP, the guy we picked does great work and word is out. Then, the more attention the gunsmiths work gets the more work they get, work = $$ and we all love money. Not wanting to turn away money leads to optimistic estimates of completion and underestimation of inefficiencies, that turns into more and more backlog, and there just aren't enough hours in the day to do the work. TIME is the one thing you cannot buy when you are the guy doing the work, and time is the one thing you need most. Pride too, he doesn't want to let anyone down so if he works a little harder he might catch up some, never happens. Then you have a job in line that pays 3 times what another job does, kids need shoes or the truck is broke or whatever, schedules can change. Also, say you have been in the shop for 10 hours without a break, but you need to get more done so you look at the backlog and there is a job you can knock out pretty quickly so the schedule changes again. You raise prices to slow it down and no help so raise prices to OMG levels to try to stem the flow and if anything you get more work because your prices are so high you must be doing great things. It can be incredibly hard to find light at the end of the tunnel so you just keep plugging away doing your best. All the while you are answering dozens to hundreds of emails and calls, all the time spent on that is time not spent turning out product. Most of the calls/emails are tire kickers, but if you treat them like the tire kickers they are now you are just a Richard Cranium and the some portion of the good work that was lost in that mess of tire kickers you didn't find goes elsewhere. Sadly this is the most likely way to get even close to caught up if you do really good work.
If ever I were to get back into a side gig I would take deposits for a spot in line, not much, maybe a hundred bucks. There are X jobs in line ahead of you, my best guess is X weeks or months until your spot, if you want the spot it's a hundred bucks. A couple weeks before your spot I will let you know so you can send your work, my best guess is the work will take X hours/days/weeks to complete without any complications, if there are complications I will let you know. Something like that.....