Quote Originally Posted by l1a1 breakdown View Post
Thanks for the supporting info so far!

This was resurrected from a $101 sportster but shoots like a dream so is worth some effort to save. There is a light rub mark made by the lower side of the bolt head in the suncorite below the bolt head track. This tapers to be a heavier rub as the bolt closes - this may be the cause of the pressure challenging this bolt head out of the track at the gap. Ill look to add a chamfered edge to the bolt head to remove this rub and pressure first. if needed the end of bolt head groove chamfers can be next. I'll de-bur and round the receiver body rail edges too.

So I'm still no further into knowing the original maker of the No4Mk1* - although the FTR work is very good and thorough!

Worst case is its a very nice parts gun if the receiver continues to lose control of the bolt head. Or it waits for a good welder in my area. I was hoping to continue with this one in CMPicon meets and the like.
If you want to save it maybe take a piece of brass flat bar of the right thickness and profile the edge to match the bolt head guide, insert under the remaining rail and get the missing bits built up with TIG welding. I guess if you really wanted to get clever, you could take a piece of say, 1/8" flat and have that profile machined into one edge about 3/16 back from the original edge. That should leave you with a little projecting block that you could machine to fit precisely to the size of the original bolt head release slot. Then all your welder has to do is work up to the edges and build up enough for you to file it back to match the original profile of the rail. Then sell or rent it to those who want to repair their own!
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