Bo,
Two things.
As far as shipping safely, it's not that hard. One CRITICAL piece of packing needs to be in the shipping container to MOSTLY eliminate the chance of stock breakage. Some factory boxes already have it. But, if you're shipping in something else it's easy enough to duplicate.
I email a photo or two of what I'm talking about to all my customers before they ship. (See the photos and some explanation at bottom of this post).
Next, there was a time years ago when my lead times had grown excessive, I'm embarrassed to say. Why? Simple--I accepted too many guns at once. I fixed that, also years ago. Now I'll keep one I'm working on and one in waiting for when that one is done--that's it. It's a simple, common sense system and it works. My apologies to any and all who ever had to wait on me when I did it the old way. I may lose work, but I won't have people tearing their hair out and mad at me.
I still add this qualifier that I ask everyone to consider: "Is this your ONLY air gun?" If so, tuning may not be right for you if you're going to count the hours, not weeks or days.
Now, to be fair I really can't speak for the other guys, but I've been around a while. Seeing what I've seen, if your tuner is a 'bling specialist' who's going to be making you a custom stock, finishing it, manufacturing custom brass bits, AND AFTER ALL THAT tuning the working parts, I could see where a guy like that could need a good bit of extra time. I specialize almost exclusively on tuning the working parts--repairing a broken stock or refinishing one is a rare exception for slower times--so I can turn my tunes over faster.
HTH.
OK, let's see what I can do with a few pics and some info here.
The most common rifle stock breakages that take place during shipping typically occur through the pistol grip. They're due to inertia trying to 'flex' or 'bend' the stock if the package containing the air rifle is dropped with the trigger guard pointing straight down at the ground/floor. The stock can't really bend, of course--instead, it breaks straight through the grain of the rifle. And, that grain travels parallel to the length of the rifle, straight through the pistol grip (aka palm swell).
Placing a hard piece of packing beneath the trigger guard, in-between the guard and the bottom of the package/case, prevents the midsection of the rifle from trying to continue traveling in a downward direction if the package is dropped. I added the second photo showing there's some height to the piece, to make it plain that it needs to be high enough, and sandwiched tightly in the case, so the trigger guard and rifle can't slip down beside it if dropped and thus still break.
The hard piece of packing can be, for instance, wadded-up newspaper and bubble wrap tightly wrapped in tape as shown in the first 2 photos, or a large, single rectangle of styrofoam as shown in the 3rd photo. The 4th photo shows where I used only a tight, hard ball of newspaper and packing tape (it may be hard to see the tape, but it's definitely there. The other 2 pieces of packing in the 4th pic are fine, yes, but it's the one beneath the trigger that's providing 99% of the protection). You just want SOMETHING there to keep the rifle from trying to bend in half.
Important: It's not obvious in any of these photos, but it's better if only one end of rifle can touch the bottom of the case, not both ends. If the end of the barrel AND the bottom end of the butt stock were both touching the bottom of the case, and the rifle was dropped downward, the piece of packing in the middle wouldn't do quite as much when it comes to keeping the stock from trying to bend at the pistol grip. You MIGHT still get a break (I know factory boxes often have end pieces, too, but the piece in the middle is perfectly-sized and perfectly-placed in those instances).
If some of you are looking at the black synthetic stock and thinking, 'that stock wouldn't break anyway, it's not wood so there's no grain to break', you might be right. But, 1. I used my own RWS 34 P with black stock as a 'dummy' example for the photo to get the point across, and 2. With erring on the side of caution usually being the wiser course, I'd probably still use that strategically-placed piece of packing just to make sure there were no nasty surprises!
Many factory shipping boxes have at least one folded piece of cardboard placed at the same location about midway down the stock, with cut-outs for the stock to fit all the way through both sides. It was meant to serve the same purpose. Have a good look at what's in the factory box--if you can tell that the stock can't go anywhere even if someone drops the box, you should be fine (many HW rifles have that, as do at least some of the Diana rifles). The problem arises when you ship your rifle in a plastic gun case or homemade box instead, so that nice piece of factory cardboard is actually sitting out in your garage in the original factory box.
The last word: Using the method I've just described, I've never had a stock of an air rifle I sent to someone else broken in transit, and no one who's used this method has ever had their stock broken when they shipped it to me. Using other methods, yes, a few people who sent their air rifle to me wound up with a broken stock when I opened their box. One had the damage covered by the carrier's insurance, while the other guy had his claim denied. If you think that separating the stock from the action is the end-all answer, it's a lot of extra trouble for me to disassemble it again and re-pack it before I send it back (I have to test the rifle as an assembled unit to make sure everything is as it should be). And, it's still no guarantee the stock won't get broken.
A word about shippers and when you can't find someone to ship your air gun: I need to check the latest wording in the FedEx manual, but some years back a FedEx manager was nice enough to provide me the section of their own manual that dealt with the shipping of firearms. In that section, not far from the beginning, there is a heading titled, "Prohibited Items". And, the first several sentences under that heading say something very-close to this (I'm too lazy to look it up this second): "Air guns and pellet guns are not firearms and may be shipped the same as other items. However, they are prohibited from being sent in International shipments".
I went to FedEx more than once with an air gun to be shipped within the USA and I was asked what I was shipping. When I told them, more than once the person I was talking to said they couldn't ship it. I told them I could show them in their own manual where it was OK, and I cited the sections I just listed. They went in the back, looked in their manual, and came out and completed the transaction. I never had one of those shipments detained in transit for any reason once it was so accepted.