I was contemplating a little more accuracy out of my Disco.It seems that a Walther Lothar barrel is hard to beat. I just can't justify the price right now.How about choking the stock barrel this way.Use a 1"-1.5" length of steel tube the same OD as your barrel then turn down the muzzle of the barrel to .001" or solarger than the ID of the short piece of tube the same length of the tube. This would require you to freeze the barrel muzzle and heat the piece of tube to install by driving the tube onto the barrel.When all is cooled the choke piece could not come off because of such a fit and should leave the barrel choked.Anyone ever try this? Would it work?
Getting that CRUSH NUT to actually strangle the barrel enough to move metal .... Not really buying a Vise having sufficiency pressure ?Mind you that I'm NOT saying it can't ... but Dang that would take MANY tons of force IMO to actually work.Hydraulic press seems the better candidate for such a thing.
The best, most repeatable, method I have seen for choking a barrel was a MONDO pipe cutter with the cutter rollers replaced with heavy duty ball bearings so that there were three bearings rotating on the muzzle and the pressure could be gradually increased with the adjustment wheel/nut.... I haven't tried it, but know the guy that does it, and he can create virtually whatever amount of choke he wants as it is a gradual and adjustable process.... I've seen some of his results, and they are indeed impressive....Bob
I really like the pipe cutter. Seems the simplest of all Keep it simple ya know. Now where to get/borrow a pipe cutter like that. That doesn't cost more than a new Walther Lothar barrel.
This is an intriguing thread with a lot of different ideas, and totally different approaches.I bet the wedding band idea could be worked out to a science for consistent results. If the band had a thick enough wall and was of sufficient tensile strength material, like a hardened tool steel, and the barrel were thinned enough so that the tensile strength of the band was strong enough to overcome the compressive strength of the inner tube, it could impart some compression on the inner tube. Seems like the metal would also have to extrude axially ( like in nced's pic), so the band probably couldn't be too long. Lloyd-ss
The guy who was doing the rolled chokes now has a webpage.... http://ramachining.blogspot.ca/Bob
Quote from: lloyd-ss on March 02, 2013, 02:39:36 PMThis is an intriguing thread with a lot of different ideas, and totally different approaches.I bet the wedding band idea could be worked out to a science for consistent results. If the band had a thick enough wall and was of sufficient tensile strength material, like a hardened tool steel, and the barrel were thinned enough so that the tensile strength of the band was strong enough to overcome the compressive strength of the inner tube, it could impart some compression on the inner tube. Seems like the metal would also have to extrude axially ( like in nced's pic), so the band probably couldn't be too long. Lloyd-ssThis one I also really like... I think I would make it a few tenth of mm conical for easier mounting, and then adjust the shrinkage by temperaturecontrol..Steel is 0,012mm pr. ° pr. meter... >> it should be possible to make about a 0,03mm shrinkage in a 250°C oven... But it would be necasary to make the choked part of the barrel rather thin walled.
Quote from: Bentxbetjent on March 02, 2013, 07:12:19 PMQuote from: lloyd-ss on March 02, 2013, 02:39:36 PMThis is an intriguing thread with a lot of different ideas, and totally different approaches.I bet the wedding band idea could be worked out to a science for consistent results. If the band had a thick enough wall and was of sufficient tensile strength material, like a hardened tool steel, and the barrel were thinned enough so that the tensile strength of the band was strong enough to overcome the compressive strength of the inner tube, it could impart some compression on the inner tube. Seems like the metal would also have to extrude axially ( like in nced's pic), so the band probably couldn't be too long. Lloyd-ssThis one I also really like... I think I would make it a few tenth of mm conical for easier mounting, and then adjust the shrinkage by temperaturecontrol..Steel is 0,012mm pr. ° pr. meter... >> it should be possible to make about a 0,03mm shrinkage in a 250°C oven... But it would be necasary to make the choked part of the barrel rather thin walled.So maybe if the band had twice the wall thickness and twice the yield strength of the barrel, maybe 1/4 (or some other percentage) of the interference fit would show up as reduced bore diameter. The remaining 3/4 would just stay as residual strain in the band. That is just a guess. Lloyd-ss