The Action strap not a difficult thing to make well if you work in leather, this is the way it works for me in a word unconventional. After a lot of looking for leather to make straps it always seemed that I would have to buy Meters of the stuff in brown or black, until a chance walk around a Pet store what a revelation. Dog and Cat Collars any length any width any colour, that was quite a number of years ago and I can say I have not bettered that for a one off leather strap with a good quality buckle that is a perfect fit. One word of caution here a good number of the collars have the buckle fitted to the strap with a large rivet, it will be a wise move to remove this and re fit with stitching because in some circumstances this rivet can eat its way into the wrist chequering.
I skive the buckle end of the strap using cause abrasive paper I have tried the knife method and I am not very successful at it, usually cutting straight through the leather on my first attempt so abrasive paper works first time every time for me. This thinning out of the leather on the buckle fold makes the strap a little more flexible making it easier for the strap to buckle up in the confines of the case. Using an impact adhesive, I close the leather around the buckle use a ruler to mark the stitch spacing and drill the holes though you could use a leather awl for the holes.
My straps are only fitted with two holes one for the anchor in the case and the other for the buckle pin, by using a quality leather I have never needed any more holes for the buckle pin because the leather does not stretch.
Because the strap is Anchored to the case with a bolt there is no hiding the fact it requires a nut to seal the whole deal. There is no way to hide that fact my answer is make a flat hand made nut from a piece of Brass the width of the strap and being a clockmaker, I have a lot of off cuts though you can us any metal you have at hand, then cover said nut with Baize so it blends in rather than making it a feature.
Just as an addition to this internal case rebuild, I have had a number of enquiries about fitting and refitting action straps in cases. This is sort of a perennial problem especially in a regularly used gun and case, I have tried a number of ways to repair this is and finally ended up with a method that works for me. There I am sure other methods out there but this method seems to be very reliable and by the way it is constructed replacing a worn or damaged strap is simplicity itself.
This is my universal kit of parts all based around a 5MM Coach bolt and the flat nut previously described the bolt’s head is filed down to approximately 1MM thick the 5mm nut filed to a square matching the bolt leaving a 1MM flange all round plus two pieces of metal approximately 1mm thick with square holes to suit the squares on either the nut or bolt to stop any turning.
Simple method first, on older canvas or leather cases that are let’s say past their best I polish the bolt head, this will now be either painted blued or brass plated. Drill through the case in the appropriate place then fit he bolt measure and cut to length having a square under the head it will not turn when the internal nut is tightened. With the bolt head being flat and thin it is a good external low cost time saving compromise.
Hidden methods 1. As a repair my preferred method is to use one of the plates depending on space. Mark around the plate making sure it is in the correct position for the strap position then cut the case Baize approximately a quarter of an inch larger all around, I prefer to use steam to soften the Adhesive holding the patch of Baize though water can sometimes work. After removing the Baize patch, you can go two ways just remove enough material to allow the bolt head to be below the surface with the plate on top or recess both head and plate. Usually case bottoms are thicker than 2MM and will accommodate bolt head and plate, decide on the bolt length you require then using an Epoxy Adhesive fit bolt and plate into the recess. Remove excess Epoxy level with the surface best dome when just setting, make a hole in the patch to clear the bolt and refit with the appropriate adhesive I prefer PVA because it is easily removed from the patch surface.
2 . Using just a nut and a plate. This I used always on a complete re Baize to a case with no fitted Action strap requirement. You would be surprised how many times after I had done the re Baize work the owner would turn up all apologetic wanting a strap fitted. It is the same method as with the bolt put it in the correct position but make sure that no adhesive can enter the nut, I used cork screwed in. My main reason for using Brass plate for this other than I had a lot was it made it far easier to find the nut under the Baize with a magnet, using a standard nut I found that I would get about two and a half turns fitting the length of threaded rod using thread lock to see it does not undo.