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Posted: 3/17/2016 3:20:11 PM EDT
| I have an old Sig516 stripped upper laying around, just the stripped upper. Gas system is long gone, I've recently been toying with the idea of building another AR. My issue is, can I build a standard DI (non piston) ar-15 with this upper? Everything seems to line up fine, I just dont want to run into any issues later down the road. |
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Quoted: I have an old Sig516 stripped upper laying around, just the stripped upper. Gas system is long gone, I've recently been toying with the idea of building another AR. My issue is, can I build a standard DI (non piston) ar-15 with this upper? Everything seems to line up fine, I just dont want to run into any issues later down the road. What do you mean the gas system is long gone? It never had a gas system. |
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Quoted:
What do you mean the gas system is long gone? It never had a gas system. Quoted:
Quoted:
I have an old Sig516 stripped upper laying around, just the stripped upper. Gas system is long gone, I've recently been toying with the idea of building another AR. My issue is, can I build a standard DI (non piston) ar-15 with this upper? Everything seems to line up fine, I just dont want to run into any issues later down the road. What do you mean the gas system is long gone? It never had a gas system. He's referring to the adjustable-regulated short-stroke gas piston. |
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A photo or two might be helpful, of the front of the receiver. The only thing I can think of is if they use a non-standard size hole where the gas tube goes for their piston setup, that would not work. I've only seen a few of these, but if I recall the pushrod assembly is about the same diameter as a traditional gas tube. |
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Quoted:
I've only seen a few of these, but if I recall the pushrod assembly is about the same diameter as a traditional gas tube. Quoted:
Quoted:
A photo or two might be helpful, of the front of the receiver. The only thing I can think of is if they use a non-standard size hole where the gas tube goes for their piston setup, that would not work. I've only seen a few of these, but if I recall the pushrod assembly is about the same diameter as a traditional gas tube. Yeah, as gamma and tweeter suggest, you have to insure the gas tube/op rod hole in the front of the upper receiver is of appropriate size. I have an LWRC AR15 upper that was a gas piston/op rod design, and I was able to use it in a DI build by pushing out their op rod bushing and installing their supplied gas tube bushing with the 4 little prongs poking into the opening. It appeared to me that the op rod bushing was the same size hole and would have worked. However, I've never seen it mentioned, but are those 4 prongs in a DI gas tube opening just for visual reference during assembly to insure proper orientation of the gas tube or something else?...cooling?...an alien conspiracy?...what?...LOL! |
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Quoted:
Yeah, as gamma and tweeter suggest, you have to insure the gas tube/op rod hole in the front of the upper receiver is of appropriate size. I have an LWRC AR15 upper that was a gas piston/op rod design, and I was able to use it in a DI build by pushing out their op rod bushing and installing their supplied gas tube bushing with the 4 little prongs poking into the opening. It appeared to me that the op rod bushing was the same size hole and would have worked. However, I've never seen it mentioned, but are those 4 prongs in a DI gas tube opening just for visual reference during assembly to insure proper orientation of the gas tube or something else?...cooling?...an alien conspiracy?...what?...LOL! Quoted:
Quoted:
Quoted:
A photo or two might be helpful, of the front of the receiver. The only thing I can think of is if they use a non-standard size hole where the gas tube goes for their piston setup, that would not work. I've only seen a few of these, but if I recall the pushrod assembly is about the same diameter as a traditional gas tube. Yeah, as gamma and tweeter suggest, you have to insure the gas tube/op rod hole in the front of the upper receiver is of appropriate size. I have an LWRC AR15 upper that was a gas piston/op rod design, and I was able to use it in a DI build by pushing out their op rod bushing and installing their supplied gas tube bushing with the 4 little prongs poking into the opening. It appeared to me that the op rod bushing was the same size hole and would have worked. However, I've never seen it mentioned, but are those 4 prongs in a DI gas tube opening just for visual reference during assembly to insure proper orientation of the gas tube or something else?...cooling?...an alien conspiracy?...what?...LOL! The upper receiver gas tube inlet hole only needs to be correctly (vertically/ horizontally) aligned and the correct diameter. The little cloverleaf pattern cut is a legacy design feature. Many aftermarket companies, especially those making from-the-ground-up side-chargers simply have a round hole. |
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My only question is if the gas tube fits properly in that non-standard design hole where their piston system used to be. I was wondering this as well. If you have a standard AR15 upper nearby could you hit those with some calipers and compare for us real quick? |
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Quoted:
I was wondering this as well. If you have a standard AR15 upper nearby could you hit those with some calipers and compare for us real quick? Quoted:
Quoted:
My only question is if the gas tube fits properly in that non-standard design hole where their piston system used to be. I was wondering this as well. If you have a standard AR15 upper nearby could you hit those with some calipers and compare for us real quick? Interesting question. I'm staring at a stripped upper right now, and his pics look right...but calipers are definitely the final judge. Good to know on the "4-prong" design of the gas tube hole just being a legacy issue. I wonder why LWRC supplied that 4-prong gas tube bushing to replace their original op rod bushing? I fitted a gas tube through the OEM op rod bushing, and it was basically the same size and clearance of a normal AR15 gas tube opening. Seems like that was some trouble for nothing. I'll bet they're using the same identical uppers on their gas piston rifles and now their new DI line of rifles. Still, seems like the 4-prong bushing in a DI upper is overkill, but I'm not complaining about LWRC's anal retentive take on this...LOL! |
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Quoted:
Interesting question. I'm staring at a stripped upper right now, and his pics look right...but calipers are definitely the final judge. Good to know on the "4-prong" design of the gas tube hole just being a legacy issue. I wonder why LWRC supplied that 4-prong gas tube bushing to replace their original op rod bushing? I fitted a gas tube through the OEM op rod bushing, and it was basically the same size and clearance of a normal AR15 gas tube opening. Seems like that was some trouble for nothing. I'll bet they're using the same identical uppers on their gas piston rifles and now their new DI line of rifles. Still, seems like the 4-prong bushing in a DI upper is overkill, but I'm not complaining about LWRC's anal retentive take on this...LOL! Quoted:
Quoted:
Quoted:
My only question is if the gas tube fits properly in that non-standard design hole where their piston system used to be. I was wondering this as well. If you have a standard AR15 upper nearby could you hit those with some calipers and compare for us real quick? Interesting question. I'm staring at a stripped upper right now, and his pics look right...but calipers are definitely the final judge. Good to know on the "4-prong" design of the gas tube hole just being a legacy issue. I wonder why LWRC supplied that 4-prong gas tube bushing to replace their original op rod bushing? I fitted a gas tube through the OEM op rod bushing, and it was basically the same size and clearance of a normal AR15 gas tube opening. Seems like that was some trouble for nothing. I'll bet they're using the same identical uppers on their gas piston rifles and now their new DI line of rifles. Still, seems like the 4-prong bushing in a DI upper is overkill, but I'm not complaining about LWRC's anal retentive take on this...LOL! That little cloverleaf pattern was designed there early-on to provide emergency pressure relief in the event that the bolt caused cartridge ignition but could not run to the rear far enough to allow enough gas to escape the upper in a timely manner. The concern was (is, for some) that if the bolt could not travel more than the required 1/8"-ish rearward needed to vent gas from the upper, and that some sort of catastrophic failure could occur. Engineers are anal retentive and so are lawyers and so are military contract writers and so are generals. If you ask me (and I realize that nobody did) I feel it makes about as much sense as giving a condom to a WoW player. The possibility of necessity is vastly over-estimated. Long story short: 1. Use lube and 2. Don't put anything in your buffer tube besides the buffer and spring... like screwdrivers, or rolls of nickels. |
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Quoted:
That little cloverleaf pattern was designed there early-on to provide emergency pressure relief in the event that the bolt caused cartridge ignition but could not run to the rear far enough to allow enough gas to escape the upper in a timely manner. The concern was (is, for some) that if the bolt could not travel more than the required 1/8"-ish rearward needed to vent gas from the upper, and that some sort of catastrophic failure could occur. Engineers are anal retentive and so are lawyers and so are military contract writers and so are generals. If you ask me (and I realize that nobody did) I feel it makes about as much sense as giving a condom to a WoW player. The possibility of necessity is vastly over-estimated. Long story short: 1. Use lube and 2. Don't put anything in your buffer tube besides the buffer and spring... like screwdrivers, or rolls of nickels. Quoted:
Quoted:
Quoted:
Quoted:
My only question is if the gas tube fits properly in that non-standard design hole where their piston system used to be. I was wondering this as well. If you have a standard AR15 upper nearby could you hit those with some calipers and compare for us real quick? Interesting question. I'm staring at a stripped upper right now, and his pics look right...but calipers are definitely the final judge. Good to know on the "4-prong" design of the gas tube hole just being a legacy issue. I wonder why LWRC supplied that 4-prong gas tube bushing to replace their original op rod bushing? I fitted a gas tube through the OEM op rod bushing, and it was basically the same size and clearance of a normal AR15 gas tube opening. Seems like that was some trouble for nothing. I'll bet they're using the same identical uppers on their gas piston rifles and now their new DI line of rifles. Still, seems like the 4-prong bushing in a DI upper is overkill, but I'm not complaining about LWRC's anal retentive take on this...LOL! That little cloverleaf pattern was designed there early-on to provide emergency pressure relief in the event that the bolt caused cartridge ignition but could not run to the rear far enough to allow enough gas to escape the upper in a timely manner. The concern was (is, for some) that if the bolt could not travel more than the required 1/8"-ish rearward needed to vent gas from the upper, and that some sort of catastrophic failure could occur. Engineers are anal retentive and so are lawyers and so are military contract writers and so are generals. If you ask me (and I realize that nobody did) I feel it makes about as much sense as giving a condom to a WoW player. The possibility of necessity is vastly over-estimated. Long story short: 1. Use lube and 2. Don't put anything in your buffer tube besides the buffer and spring... like screwdrivers, or rolls of nickels. Rolls of nickels?...you are an El Cheapo Grande! The rest of us are using quarters! 
But seriously, thanks for that description on the 4 prong design...alternative emergency exhaust port...so to speak. |
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