Please post pics of your failed breech block, as well as any other parts affected (firing pin & spring, guide, etc).
What kind of ammunition were you firing - reloads, commercial brands, military, and any identifying data on it (bullet type & weight, intended use [target, match, plinking, etc] as well as age (new, old military, old powder, etc).
As stated above, even a well repaired breechblock is not safe to use again. The steel becomes brittle with prolonged use and although the welded part may be strong, the rest of the breechblock will now become the 'weakest link'.
Best bet if you intend to fire it is to get a new [new to you, not necessarily made yesterday] breechblock/toggle train for firing and use the original (if it matches) for display.