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Discussion Starter · #1 ·
I've heard conflicting reports from Robinson as to if these ever existed, but I saw an ad for a rifle with one back in 2018. I'm looking to side-mount an IR device, so my current mlok upper is probably adequate, but not ideal. Only interested in the stripped upper, I have my own bits to put in a Mini, and would buy a new barrel assembly if Standard. I'm not in any rush, and honestly don't have very high hopes of finding one, but I figured I'd put out some feelers in case this gets stumbled upon.

Thanks in advance.
 

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I have one of the standards....They were made. Mine's been modified as a test piece to see if I could build a custom 12" set up with the standard length upper but in keymod, so I'm sure it's not what you're looking for.
 

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Discussion Starter · #3 ·
So what you're saying is you milled the quad rail off for keymod? I'm confused. Having a 12" barrel in a standard upper is something I'd be interested in, actually.
 

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So what you're saying is you milled the quad rail off for keymod? I'm confused. Having a 12" barrel in a standard upper is something I'd be interested in, actually.
No, I milled the inside channel of a quad rail -M std. upper for the gas piston and gas block to fit further down inside the handguard on a full pic rail model. Then I cut a roughly 45º angle on it to access the dial on the Type 3 block....as proof of concept. I was trying to end up with a lighter, slimmer 12" bbl -M. So once I figured out I could do it with my limited tooling, I did it to a new Keymod upper (and did a little cleaner interior cut)....came out really nice, IMO.

Let me see if I can find the link to the thread.
 

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Just took one....

15309

You can kind of see inside that the webbing had to be cut out with a end mill....but you only need to do this if you're trying to stuff a mini length gas system in std size upper.
 

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Discussion Starter · #10 ·
That's pretty interesting. I don't imagine it would be functional with my type 2 mini gas system, but I might buy that if I end up switching to type 3.
 

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That's pretty interesting. I don't imagine it would be functional with my type 2 mini gas system, but I might buy that if I end up switching to type 3.
Yeah, wouldn't work with a Type 2. I have Type 2 on my first 16" XCR-M.

And JFYI...I wasn't attempting to sell it to you....just show you how it was done.
 

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Pretty certain there were quad rail mini length uppers when the -M first came out....thought Bravo had one (anyone remember for sure)....it was a few ounces lighter IIRC.

You'd need one of those if you want to keep your Type 2 gas system.

If you wanted to build a 12" with a Type 3....you'd need to do what I did (unless RA took my suggestion to just mill the std upper to clear buried Type 3 mini gas blocks/dials...but adjustment would be a bitch w/o that 45° cut, which is probably why they didn't...or they'd have to change the layout of the vent holes).

If you decide to go with a buried Type 3 block in a standard quad rail upper, I will help you out with it. You're new here, but that's sort of our "thing" around here....helping.

Just let me know.

Best of luck with your decision.
 

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Discussion Starter · #14 ·
I've lurked here a bit before I bought mine, a lot of good insight around here. I'm not married to my current barrel, if it means I can get a better mounting point for my IR laser. I do prefer the Type 2 gas system, so hopefully an upper will materialize. Thanks for all your help!
 

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I've lurked here a bit before I bought mine, a lot of good insight around here. I'm not married to my current barrel, if it means I can get a better mounting point for my IR laser. I do prefer the Type 2 gas system, so hopefully an upper will materialize. Thanks for all your help!
Well, here's the deal....if you want my quad rail upper, you're welcome to it for free. I'll send it to you, if you can use it; great....send me back cash (fuck Biden and his new bullshit regs for Paypal, Venmo, Zelle, etc) for the shipping and it's yours. Only condition is, if you can't use it...pay it forward and just give it to whoever might be able to instead. If you can't use it, don't want to store it, and can't find anyone who needs it, send it back to me.

Fair enough?

If I were you, I'd keep looking for a mini length quad rail upper so you can keep the gas system you prefer (though of the 2, I like the Type 3 much better), but if you're looking at building a 12" bbl version or a mini-gas system in a standard upper....mine would serve you well. Keep in mind there may be a mini quad rail upper guy out there that wants the slimmer profile of KeyMod (KM) or MLok and is just waiting to recoup some of the cost of buying an upper from RA. Of course with lead times being what they are as well as the fact that uppers are STUPID expensive ($600 for one; $700 for competition) no one may be willing to part a working rifle and wait for the new upper....but if you have my upper, you could send it to them to use while they wait for RA to deliver a new one.

All depends on what you're willing to pay for an upper too, obviously.

LMK.
 
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Discussion Starter · #16 ·
If you don't want it, I'd be happy to have it. I'll PM you my address.

Why do you prefer the type 3 over the 2, out of curiosity? As I understand it, the 2 runs cooler and cleaner than the 3, and also doesn't have any "port pop" when firing suppressed.
 

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If you don't want it, I'd be happy to have it. I'll PM you my address.

Why do you prefer the type 3 over the 2, out of curiosity? As I understand it, the 2 runs cooler and cleaner than the 3, and also doesn't have any "port pop" when firing suppressed.
Not a big M1A tappet fan personally. Never have heard the 2 runs cooler/cleaner....what's your source (though fouling/heat have NEVER been an issue with any of my XCRs). Haven't fired my Type 2 with a can, but I'm not familiar with "port pop" on my Type 3s....My cans are all flow through designs though....so there's very little cyclic rate increase or increased backpressure.
 

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Discussion Starter · #18 ·
Not a big M1A tappet fan personally. Never have heard the 2 runs cooler/cleaner....what's your source (though fouling/heat have NEVER been an issue with any of my XCRs). Haven't fired my Type 2 with a can, but I'm not familiar with "port pop" on my Type 3s....My cans are all flow through designs though....so there's very little cyclic rate increase or increased backpressure.
Generally, I've understood short stroke pistons to have the advantage in those regards. I know I've heard plenty of complaining from PWS AR owners about their handguards heating up pretty fast. Presumably it's from the long stroke system dumping more gas into the handguard than a short stroke would. As for port pop, I was talking to an owner on another site who said that the type 3s make a popping noise when used with traditional baffle suppressors, which I prefer over flow-through designs, personally.
 

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Generally, I've understood short stroke pistons to have the advantage in those regards. I know I've heard plenty of complaining from PWS AR owners about their handguards heating up pretty fast. Presumably it's from the long stroke system dumping more gas into the handguard than a short stroke would. As for port pop, I was talking to an owner on another site who said that the type 3s make a popping noise when used with traditional baffle suppressors, which I prefer over flow-through designs, personally.
Yeah, I have had a couple of short stroke LWRCs and they didn't seem any more immune to heating up the handguard with very fast semi auto fire than any of my Type 1 and Type 3 XCRs.

May I ask why you prefer a baffle suppressor over a flow through?
 

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Discussion Starter · #20 ·
Yeah, I have had a couple of short stroke LWRCs and they didn't seem any more immune to heating up the handguard with very fast semi auto fire than any of my Type 1 and Type 3 XCRs.

May I ask why you prefer a baffle suppressor over a flow through?
Maybe my concern is unfounded in that case.

As for suppressors, it's size, weight, and signature reduction. I haven't found any flow-through designs that compare to higher-end baffle suppressors in those categories. My rifle is enough of a pig without hanging a 20oz OSS can on the end of it, which won't even suppress as well as a 12oz baffle can. Especially with an adjustable gas block to mitigate the increased backpressure, I don't see the point. I'm really interested to see what comes of the technology in the next few years, though, especially with advances in additive manufacturing.
 
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