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Old 10-11-2017, 08:43 PM
southfork southfork is offline
Join Date: Mar 2011
Location: Idaho
Posts: 501
Default Solid Piston nut (no gas piston)

I was reading a 30-year-old issue of the American Rifleman magazine today where the magazine's technical editor was describing the three ways commonly used by carbine owners back then to change an M1 Carbine into a "bolt-action repeater:" (1) drilling a hole in the slide arm where the gas piston would normally hit it, so the piston ends up not hitting it; (2) shortening the piston, so again, the piston doesn't hit the slide arm; and (3) replacing both the piston and the piston nut with a solid threaded plug so no gas escapes the barrel.

The third mentioned method was described as the best of the three methods, and was considered "safe". I would be interested to know if such "threaded plugs" to replace the piston and nut are commercially available today. Or, if not, if any old timers on this forum might have one or two in their carbine parts bin.?Has anyone ever done a conversion to a manually operated carbine using one of the 3 methods mentioned above?
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Old 10-11-2017, 08:49 PM
Jakeroub Jakeroub is offline
Join Date: Dec 2016
Location: Mass
Posts: 451

Just curious- but, why would you want to turn your carbine into a bolt action???
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Old 10-11-2017, 09:27 PM
southfork southfork is offline
Join Date: Mar 2011
Location: Idaho
Posts: 501

Only because both the receiver and its slide arm are worn way out of spec where they slide, and I don't want the slide arm to pop out under piston pressure. If no piston impact, then no worries. Otherwise, I've only got a wall hanger.
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Old 10-11-2017, 10:18 PM
goofycat goofycat is offline
Join Date: Dec 2015
Location: Tn.
Posts: 23

I'm not sure what the thread is on the nut, but you might could pull one out and check the threads and see if you can find a set screw with Allen wrench head that is short enough to bottom out with the top flush. Would serve the same purpose.
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Old 10-12-2017, 05:11 AM
J D Shelby J D Shelby is offline
Join Date: Dec 2013
Location: Hampton Roads Virginia
Posts: 235

The thread is 1/2" 32 thread per inch. If that is any help.
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Old 10-12-2017, 06:29 AM
309Carbine 309Carbine is offline
Join Date: Feb 2017
Location: South Mississippi
Posts: 171

Universal actually patented a gas piston design in which one could change to semi-auto or single shot action by rotating the piston. It was a solid piston held by a pin and not a threaded system. I would think one could find a plug, or have one made like previously mentioned. If you have already condemned the gun, you could have the piston brazed or silver-soldered in place.....or even pin it in place, but that may be an extreme measure and only considered if you never plan to use that barrel again.
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Old 10-12-2017, 08:00 AM
twh1997 twh1997 is offline
Join Date: Oct 2009
Posts: 757

Could you build up the tab on the slide to make it fit the worn receiver versus the solid piston idea?
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Old 10-12-2017, 10:17 AM
meplat meplat is offline
Join Date: Jan 2010
Location: Prescott, AZ
Posts: 3,745

A redneck way to the same might use one or more "washers", perhaps cut from a piece of tubing, which fit over the external extension of the gas piston. When assembled over the piston inside the cylinder, this addon would prevent motion of the piston under gas pressure.

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Old 10-12-2017, 10:34 AM
skohler skohler is offline
Join Date: Nov 2009
Location: Gettysburg, PA
Posts: 293

Seems like receivers, bolts, firing pins, barrels are welded to make them not work. How about a small weld on the piston/nut to keep it from moving? I would think it better to use one that was out of spec anyway or having trouble before ruining one that functions well. Getting something to not work seems way easier than the other way around.
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Old 10-12-2017, 10:45 AM
HB of CJ HB of CJ is offline
Join Date: Nov 2011
Location: 42N -123W OR USA Kinda
Posts: 1,193
Default Commercially Available Plug? ...

Back in 1965, (am I THAT old?) there were commercially available aforementioned solid Carbine action plugs that did exactly what was alluded to? Shut off all gas and turned the Carbine into a straight pull repeating "bolt action" rifle. If memory serves.

Some rifle ranges back then required such. No high cap mags. No rapid fire. Pretty much just "sighting in" ranges. The instructions read that after removing the plug, reaming the gas port out with a .070 drill bit might be necessary? Too long ago.


Last edited by HB of CJ; 10-12-2017 at 02:19 PM. Reason: edited
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