Trunion

[weasel]

I have read that some builders of the SA42 weld the trunion to the receiver. I understand that this was to help the receiver from splitting at the trunion area. It is my understanding that welding a hard metal to a soft metal will in time create weld failure. I may be wrong in this thinking,
but I have seen welds crack when unlike hard/soft metals are joined.
Does anyone have expertise in this type of welding? What will one do when the trunion fails if it is welded to the receiver, cut out the welds?
My .02

[ak47dennis]

I don’t know why on gods green earth you would ever need to do this if your receiver is within spec. and the trunion is riveted properly. This to me seems like a big band aid for out spec receivers that I would be willing to bet the farm on. I have examined many MG42’s and parts kits and have NEVER seen this nor would a German waffenmeister do something like this.

[ak47dennis]

I have read that some builders of the SA42 weld the trunion to the receiver. I understand that this was to help the receiver from splitting at the trunion area. It is my understanding that welding a hard metal to a soft metal will in time create weld failure. I may be wrong in this thinking,
but I have seen welds crack when unlike hard/soft metals are joined.
Does anyone have expertise in this type of welding? What will one do when the trunion fails if it is welded to the receiver, cut out the welds?
My .02

On another note: why would a properly welded gun split

[Abwehr]

What I have read is that the entire receiver of the MG42 will actually "twist" during firing from the rotation of the bullets going down the barrel. Although the "twist" is minimal, and the gun was designed to do this, welding the Trunnion to the receiver can cause a "crack" in the receiver. When the Trunnion is welded, the receiver is then not allowed to "twist" as designed, and a crack will form in the receiver.

This is what I have been told, but I can't verify the information. It sure sounds reasonable.

[drooling idiot]

I have read that some builders of the SA42 weld the trunnion to the receiver. I understand that this was to help the receiver from splitting at the trunnion area.

my opinion is this is a bad idea . there is enough metal to get a good weld without worrying about the receiver separating under the trunnion. if your one of the "worrying type" then there is extra clearance between the barrel and the upper section of the receiver , I'd build that up.

[weasel]

I didn't weld my trunion on my SA. What I read was a report from a fellow who had a BRP 42 which cracked at the trunion. He sent it back and their way of fixing the problem was to weld the trunion to the receiver. This info was read on the 1919a4 forum. It was hard to think that welding was the right way to fix the SA.
I spent time to fit the trunion on my SA, drilled out the rivet hole to .250, put in a bolt for testing, easy to replace with rivet. LOL with all your builds
Weasel

[gearlogo]

I think you would be better off seeing if the thing functions first. I have seen recievers that have built up areas of weld to line up the trunion. these welds just make pads for the trunion to rest on and are not welded to it. It is important that the trunion float. How much it matters I dont know. Most semi conversion leave out the bolt lock. I would not want to change anything that might cause an out of battery incident.