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Old February 17, 2020, 20:36   #1
D P Six
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Semi auto with suppressor won't function

An acquaintance of mine had the barrel threaded for a suppressor on his BAR in 270. He then found that with the suppressor mounted the rifle would not function in semi auto. I do not know the particulars of what the gun was doing; failure to feel fresh round, failure to reset trigger, failure to eject ... etc. Any idea what's causing the problem. Possible solution.
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Old February 17, 2020, 20:52   #2
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May need more gas to cycle the action, maybe?

Do BARs have some way to adjust the gas system?
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Old February 17, 2020, 21:26   #3
D P Six
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Quote:
Originally Posted by easttex View Post
May need more gas to cycle the action, maybe?

Do BARs have some way to adjust the gas system?
I was guessing the backpressure from the suppressor was causing an over pressure or timing issue. Don't know if the gas system is adjustable ... never handled that model of Browning. Thank you.
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Old February 18, 2020, 20:31   #4
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Defintely an over pressure situation. From past memories of cleaning a BAR years ago... the BAR has an inertia piece mounted on the recoil guide and spring, which I assume the additional gasses and pressures are overcoming too fast and not allowing enough dwell time within the gas system to accumulate a large enough volume of gas to fully operate the recoil system. (just a guess) Basically the the gas system is probably functioning way too fast like the last posters says and throwing the timing off...bleeding some gas from the system would probably help (but I don't know if that's possible) or adding weight to the inertia piece would slow things down.
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Old February 19, 2020, 09:00   #5
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That's what I was thinking. I don't know what the part is called, but inertia piece works for me. Too much pressure and it can't unlock.

You need to restrict the gas

https://www.youtube.com/watch?v=qP31BMuhGWc
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Old February 19, 2020, 09:44   #6
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The owner is using 270 /130gr. Would using a heavier bullet, 160gr, make any difference better or worse. I suggested he buy a bolt action and start over.
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Old February 19, 2020, 18:49   #7
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I can't answer the ammo question with any authority but trying extremely light and extremely heavy ammo would be an option.
I would assume very light grain weight bullets would be better than heavy...in "theory" the increased back pressure from a suppressor combined with lower pressure from smaller grain weight bullets might be more like the operating pressures of a heavy grain weight bullet for any given caliber...
Buying a dedicated Bolt gun would probably be cheaper than trying to modify a BAR for his intended purposes IF he can't find a suitable ammo. As gun Plumber stated RESTRICTING the gas flow into the gas piston (possibly buy a piston and reduce the port(s), or figure a way to VENT excess gas before the port (you LOSE SUPPRESSION much like the FAL gas block makes a noticeable"pop"....regardless, its gonna be expensive to alter and experiment and change and in the end he will have a dedicated mediocre suppressor gun or a butchered BAR that he can't suppress. Either way, BAR's are not known for their ability to tolerate carbon/powder residue and function reliably and a suppressor will fill the gas system up FAST with all sorts of junk.
Good Luck...
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