M*CARBO Brotherhood

Recoilless charging handle + buffer pad issue with bolt hołd open

Hello everybody,

As we do have latelly some products from Kel-Tec naturally we start to order Mcarbo stuff.
I have some issues with combination recoilless charging handle + buffer pad.
I cannot hook the handle to make bolt hold open.
I check it already 3 times and assembly looks correct.
Need like 1/5 of an ich to make this work.
What am I missing?

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Welcome to the brotherhood!
I would move your post into this thread if i could.

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Ok, thank you. I have checked assembly. New pin is in the spring, and it is aligned into this small hole into charging handle. I think I will try to check if spring seats correct in this plastic tube cap.
Maybe donut need to get some shots?

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So finally I was succesfull. But it need a lot of force to do that. Hard to do this with one hand.

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I reply to myself but maybe someone will do the same thing. So when I istaled this new pin on the main spring i twisted this internal rod by 180 degrees and it made kind of X inside od the spring coils.
It blocked spring and she could not get compress while in buffertube.
Now everything works like a champ.

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The buffer will also break in and soften up a bit as you get more rounds through it.
Mine got better after a couple hundred.

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even if you twisted it 180 and locked the pin into the charging handle, the tail end of the recoil spring is not attached to anything, it should naturally straighten out in the channel, into the end buffer assembly.
The hard part is keeping it seated in the buffer assembly. The mCarbo recoil buffer helps on assembly with that. Or during assembly without the “donut” have bolt back, still above hammer to hold it down, then insert into buffer assembly center, slide it all in pushing on buffer until you seat charging handle.
buffer assembly
mCarbo recoil buffer

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If you think about even the spring “catching” on something, it should still compress more than enough to lock charging handle back. You compress it quite a bit when installing locking pin right? So it should compress an extra few mm’s to seat handle locked.
You may have a physical obstruction, burrs on bolt, inside recoil tube, bolt misaligned and binding.
I smoothed out my bolt(s) exterior with very fine emery cloth and deburred tube interior with a 12 gauge shotgun brush. Another physical trait of bolts in tubes is too small a bolt in tube, and when under pressure loses parallel alignment, tilting and binding. I would think doubtful, but that is physical properties of items in tubes binding under pressure and resulting in being not parallel in direction of travel.

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You have 2 rods inside od the main spring. I did what you see with this x twist. So when spring compressed rods had kind of blockade on its way.

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the two piece rod is to allow a solid end stop to spring EXPANSION and still allow it to collapse and allow spring COMPRESSION. clever design actually. And on a cycle, the spring and rods should go to a natural “relaxed” state, what would stop that is both ends being locked into something, and as it only one end locked, the pin into the charging handle, bolt end. The tail end, to buffer assembly is not locked and free to rotate, allowing the spring and rods to stay naturally not in a bind.