German websites such as Egun often have for sale used muzzle-length insert barrels for shotgun barrels, especially for combination guns. How adaptable are these to other firearms? For instance, can they be shortened for a shorter length barrel than the original barrel, and the muzzle-adjustment part simply screwed back on to allow the necessary POI adjustments?
Also, can they be adapted for a different sized choke? For instance, do they need to be turned down or shimmed up to fit a new choke diameter? Or are they universal fitting rather than a custom fit for a specific gun?
I can see that the extractor needs to be modified, but I'm told this is not too difficult in itself for a good gunsmith. In short, could one of these muzzle-length inserts be purchased and fitted by a competent gunsmith in a country where these devices are largely unknown?
