KazO

Hello All, New to the forum and heat treatment of any kind, so bear with me. My interest in this field started with my sport shotgun problems. Beretta hand made, part (sear) not available. I'm fairly competent DIY in gunsmithing, have right now 8 guns for hunting and sport shooting (Olympic Trap), and so far (with some mistakes) fixing them all. With the one at hand, trigger pull got lighter and lighter (was on the lighter side from the beginning) to the point that I stopped using it, had a premature discharge almost every round I shot, not safe. It is one of the best shotguns for the discipline SO5, quite likely was used in Sydney Olympics, beautiful and we fit each other. I found that someone (previous owner?) worked on the sear, most likely to get a light trigger, but it wasn't done properly and I had to reprofile the sear-hammer engagement substantially. The fact that over a course of half season the the trigger pull changed, was telling me that the part wasn't re-hardened. So not to have the same problem down the road I started my 'research' how to do it. That should do for opening Got the torch, propane forge, pack carburizing compound, Cherry Red, even hardness tester, plus more ancillaries. And educating myself, trying to understand iron-carbon phase diagrams, how it all works, found it very interesting and for sure complicated. Decided to go Cherry Red way, it's not ideal solution as I learned the trigger assy components (sears, hammers and more) are made from 17NiCrMo6-4 alloy that was carburized, and low C content (.14-.20%) would not respond well to Cherry Red; and was considering re-carbonizing, hence the forge, well, I may use it after all and start making some knives, have some antler, calling for it. Red how to make it fit for the job, Rigidizing, and the application of refractory cement [Simond Store 5 Pound Refractory Cement – 3000F Rated - High Temperature Refractory Coating for Ceramic Fiber Blanket Lining in Forge, Kiln, Smelting Furnace] The 1st coat went well, no cracks, waited for about 24hrs to apply the 2nd, and as it often happens didn't stick to slogan 'less is more' and the next day the picture says all, same story with the top lid Reading again, conflicting info, confounds me, don't want to go 3rd time with this. The crack go down 1/3 all around, about 1mm wide. Please direct me how to deal/repair this. TIA, Kaz p.s. couldn't help myself not to show you the gun ;)