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MG42 trunnion numbering


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I've heard that, in the "just left the factory" condition, an MG42 may have numbering on the "trunnion" that is different from the serial numbers on the rest of the gun (and that the trunnion is matched to itself). Is this correct? If so, is there any known relationship between the numbering on the trunnion and the numbering on the receiver?


Am I right in thinking that the trunnion numbering is the circled number shown in the attached picture?


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Yes, that is correct. The two parts were machined together to provide accurate alignment of the unlocking cams milled into the inside faces of each part and alignment of the rivet holes for correct assembly. Mating numbers clearly number on each part.

The ID of the trunnion maker and inspector marks, etc are also stamped on the parts. Trunnions were made by the assemblers and assembled to their guns, but makers other than the assemblers are found on the guns as well.
The alloy from which the trunnions were made is very hard and with that characteristic comes brittleness. Every shot fired recoils the barrel and the front end of each cam is impacted by the inside front wall of the barrel extension. The impact is mitigated by the very stiff springs in the barrel recuperator. The recuperator springs need to be kept in top condition to mitigate the impact on the front end of the cams and if the springs break, take a set, or are compromised, the cam ends will will decay, chip and fracture. This can lead to out-of-battery ignition due to failure of the recuperator to return the barrel to rest between every shot. OOB ignition can do mild damage or in the extreme blow the extractor through the bottom of the receiver along with bent topcovers, bulged receiver bottoms, bent barrel change doors, etc.

Many 42s have been reblued during the collector era, and one way to tell is if the trunnion has a purple/red color cast to it. The steel alloy of the trunnion requires special bluing treatment to prevent this, but that has rarely been done. Just a tip. FWIW

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Thanks, BRMCII,


Might I ask you some further questions in my hunt for a decent MG42. I've messaged you on a different board, but I'll replicate here.


I'm looking at a few guns, but am struggling to find one which is in, or close to, all original condition (and not diluted by MG53, or even M3 parts). One particular weapon has a Yugo bolt, but otherwise looks decent. I'm wondering whether to grab it, or hold out for a (potentially elusive) all original. How rare are all original guns?


If you wouldn't mind casting an eye over the attached pictures - of the gun I'm currently looking at - to see if you can see any problematic post-war parts, I'd be extremely grateful. I can't see any Yugo serial nos.


Thanks for any help you can provide.













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