Bren Piston Post

Hi Gents,

What exactly is the difference between a Mk1 and Mk2 Piston post? If I understand correctly the Mk2 post was an upgrade to all Bren's but what was the change. I can see that the Mk2 plunger is longer but is there a physical difference in the post? The spring is the same, is it not? Again I understand the extension to be the same as well and we can all see the difference in a Mk2 gas piston but what's the story with the piston post?

That was always a good Armourers trade test question or one that the instructor, the most dis-likeable Harry Weeks would ask some unfortunate apprentice to come out to the front of the class and explain, as if teaching a class himself. Once he'd tied himself up a bit with his lack of technical expertise or inexperience or just inability to speak out loud to the class, Harry, we called him SIR, spelled CUR, would berate him on front of everyone. Another good one was the extractor trackway of the .300" M1919 Browning. I always had a dream that IF I was ever Commissioned (and I was much later) it'd give me much pleasure to walk into his class and while he was surrounded by his apprentices I could say ,..... stand up when I come in Mr Weeks' . Yes....., where was I?

The depth of the guide hole for the longer plunger, spring, piston post. If you use a longer plunger in a short holed piston post, it will bottom out every time the post unlocks the breech block (it is in fact an unlocking buffer), burr over and jamb up to buggery inside the hole in the piston post

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Thanks Peter,

That sets me on the right track.

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Originally Posted by Peter Laidler

That was always a good Armourers trade test question or one that the instructor, the most dis-likeable Harry Weeks would ask some unfortunate apprentice to come out to the front of the class and explain, as if teaching a class himself. Once he'd tied himself up a bit with his lack of technical expertise or inexperience or just inability to speak out loud to the class, Harry, we called him SIR, spelled CUR, would berate him on front of everyone. Another good one was the extractor trackway of the .300" M1919 Browning. I always had a dream that IF I was ever Commissioned (and I was much later) it'd give me much pleasure to walk into his class and while he was surrounded by his apprentices I could say ,..... stand up when I come in Mr Weeks' . Yes....., where was I?

The depth of the guide hole for the longer plunger, spring, piston post. If you use a longer plunger in a short holed piston post, it will bottom out every time the post unlocks the breech block (it is in fact an unlocking buffer), burr over and jamb up to buggery inside the hole in the piston post

Next question

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Sorry Peter, would you (or anyone) have the correct depth for the Mk2 piston post guide hole? I have five piston posts, a couple sold to me as Mk1 but they all have the same depth from the spring and plunger opening to the bottom of the guide hole recess, it's about 81.5mm. I'm guessing they are all Mk2 but want to be sure I'm installing the right plungers.

Regards

DOD