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MCX: Generation 3/SPEAR LT (Page 47 of 47)
My LT 11.5 conversion kit was supposed to arrive today, but actually got here Saturday! The middle device came off after using a little bit of force, but I’ve dealt with worse on other rifles. The Gemtech bilock is a place holder until my TBAC Spiro comes in. 
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Your painted rifle is ugly, but I’m uglier, so send it to me and I’ll make it look good!
If it weren’t for double standards, we’d have no standards at all.
If it weren’t for double standards, we’d have no standards at all.
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Originally Posted By Claytonhoneyberry: My LT 11.5 conversion kit was supposed to arrive today, but actually got here Saturday! The middle device came off after using a little bit of force, but I've dealt with worse on other rifles. The Gemtech bilock is a place holder until my TBAC Spiro comes in. https://www.ar15.com/media/mediaFiles/515930/20260504_084340-3757290.jpg |
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Originally Posted By Roadblock: I'm really liking these Skeletonized 2.0 stocks... Originally Posted By Roadblock: Originally Posted By Claytonhoneyberry: My LT 11.5 conversion kit was supposed to arrive today, but actually got here Saturday! The middle device came off after using a little bit of force, but I've dealt with worse on other rifles. The Gemtech bilock is a place holder until my TBAC Spiro comes in. https://www.ar15.com/media/mediaFiles/515930/20260504_084340-3757290.jpg I got it for the length, not knowing if I’d like the height of it. Both feel perfect. I’m very happy with it. |
Your painted rifle is ugly, but I’m uglier, so send it to me and I’ll make it look good!
If it weren’t for double standards, we’d have no standards at all.
If it weren’t for double standards, we’d have no standards at all.
Just a little bit of info, a video with tfbtv or what ever it is on the development of the spear mcx, its a long video, play it at 1.25 speed. The Truth About the SIG MCX From a Guy Who Built It |
"I am gonna laugh my ass off looking out the air vent of the box car watching some of you shot in the head in a ditch when you finally realize it's time to resist." stolen from RR_broccoli
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Originally Posted By StaccatoC2: Just a little bit of info, a video with tfbtv or what ever it is on the development of the spear mcx, it’s a long video, play it at 1.25 speed. I thought his explanation of how the platform continuously evolved to meet new (military) customer requirements, resulting in what the commercial market saw as multiple generations of the rifle, was very helpful. The parts about the 300 BLK magazine and the steel feed ramp insert resulting from their 7.62x39 experience were also interesting. |
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Any strong opinions on the omega valve? Suppressing an 11.5” and debating between a polonium and omega, or just getting a CAT can and using the factory gas plug. Price difference isn’t much, but the last time I messed with a baffle can on a Virtus, I walked away looking like a coal miner. |
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Originally Posted By rb889: Any strong opinions on the omega valve? Suppressing an 11.5" and debating between a polonium and omega, or just getting a CAT can and using the factory gas plug. Price difference isn't much, but the last time I messed with a baffle can on a Virtus, I walked away looking like a coal miner. Standard back pressure, high flow, surge bypass, any of them can we tweaked to be better with an Omega valve. Just keep in mind that a standard can like an RC2 is going to see more benefit. |
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Originally Posted By Roadblock: You want an Omega valve regardless of which can you get. I'm surprised SIG hasn't done this yet actually. Standard back pressure, high flow, surge bypass, any of them can we tweaked to be better with an Omega valve. Just keep in mind that a standard can like an RC2 is going to see more benefit. Originally Posted By Roadblock: Originally Posted By rb889: Any strong opinions on the omega valve? Suppressing an 11.5" and debating between a polonium and omega, or just getting a CAT can and using the factory gas plug. Price difference isn't much, but the last time I messed with a baffle can on a Virtus, I walked away looking like a coal miner. Standard back pressure, high flow, surge bypass, any of them can we tweaked to be better with an Omega valve. Just keep in mind that a standard can like an RC2 is going to see more benefit. I figured, I’m just trying to find out if an omega cuts down on gas to the face enough to warrant going that route. |
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Back again with the updated OMM mid board. Much better fit with the LA23. Hope to add in an Omega valve sooner than later as well. Attached File Attached File |
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Originally Posted By Roadblock: Anyone got that new Romeo 8T AMR Shroud on their LT yet? |
I don’t want unity. I want them defeated and subjugated, and I never want them to be a threat to me or my people ever again. - J. Grey
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Originally Posted By CavScout: I have it on my HK with a Juliet 4x magnifier but the eyebox sucks on this 4x. Not really interested in the magnet BS, I never change my reticle on my 4T PRO now. How do you like the optic itself? I'm pretty sure I'm set on getting one, looks DAMN sexy and I like it more than the 8T and 8T AMR. |
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Originally Posted By JK-919: What’s the state of these things in 2026? Been considering a 11.5” 5.56 or rattler LT. Or should I wait for the unfortunately named Beretta NARP? Seems like the one with thousands out in the wild might be a safer bet. |
BikerNut:
Normal people like motorcycles. Real people like motorcycles.
People who don't like motorcycles are just... weird.
Normal people like motorcycles. Real people like motorcycles.
People who don't like motorcycles are just... weird.
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Originally Posted By JK-919: What’s the state of these things in 2026? Been considering a 11.5” 5.56 or rattler LT. Or should I wait for the unfortunately named Beretta NARP? My vote is a Rattler LT of some flavor. The MCX thrives in ultra short configurations. My RSAR is my absolute favorite 5.56 setup, I genuinely never expected that to happen. |
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Originally Posted By kwb377: Depends on what you mainly want to use it for. Originally Posted By kwb377: Originally Posted By JK-919: Whoops should’ve specified 300 blk for the rattler or 5.56 for the 11.5. Depends on what you mainly want to use it for. I started down the rabbit hole of 9” 5.56 vs 6.75” 300Blk, since both would fit in the bag I’ve got. 300 fits with can attached, 5.56 needs it separated. This is assuming I can actually get my damn hands on a 9” or even 10” barrel/upper… Anyway. 5.56 still wins out in terms of effectiveness once you factor in defensive ammo, since 300blk needs pricer ammunition to be effective, and the best 5.56 options can be had cheaper than decent/mediocre 300Blk. Only real utility I see in the 300 is using subsonic ammo, which would have its own incredibly useful advantages if you ever had to deploy said weapon, since gunfire is like a dinner bell for shitbags. Unfortunately, it seems like there aren’t many good options; Hornady sub-X is relatively affordable, but mediocre. Lehigh does pretty well in testing, but the projectiles are more expensive than full Sub-X cartridges  Plus subsonic FMJ is around 70 cents a round. I’m not really a fan of switching between supers and subs in the field, changing your POI and the rifle’s gassing just seems like a bad idea to me. I’m sure I could zero the supers, run and numbers, and get subs on paper to see where the holds are, but damn, that’s a lot of extra headache and stuff to try and remember under stress. Anyone else had this same debate? |
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A lot of folks are running dual optics now, or for the super rich (aka tax payer money) optics like the Romeo9T. Aimpoint made the Comp M5b which had ballistic turrets where you could custom set different zeros, like for supers and subs, for example. Sadly, I believe it is discontinued now. CAG mostly just uses EOtechs and learns their holds. But again, they have taxpayer money for ammo and training. Me, personally, I run a red dot on a Unity riser with the attached Unity offset mount. Top dot zeroed for supers, angled dot zeroed for subs. I'd like to play around with the Holosun DRS-TH, which lets you display both reticles at the same time. 300blk's only reason for existence is that it is a dual-use round. If you want dedicated subs, there have always been better options. If you want supers, there have always been better options. I'd even suggest that 338ARC is over-compromised compared to 300blk. It gives up so much supersonic performance that they should have only optimized for subs and just given up on supers. |
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Originally Posted By SpyHawk: A lot of folks are running dual optics now, or for the super rich (aka tax payer money) optics like the Romeo9T. Aimpoint made the Comp M5b which had ballistic turrets where you could custom set different zeros, like for supers and subs, for example. Sadly, I believe it is discontinued now. CAG mostly just uses EOtechs and learns their holds. But again, they have taxpayer money for ammo and training. Me, personally, I run a red dot on a Unity riser with the attached Unity offset mount. Top dot zeroed for supers, angled dot zeroed for subs. I'd like to play around with the Holosun DRS-TH, which lets you display both reticles at the same time. 300blk's only reason for existence is that it is a dual-use round. If you want dedicated subs, there have always been better options. If you want supers, there have always been better options. I'd even suggest that 338ARC is over-compromised compared to 300blk. It gives up so much supersonic performance that they should have only optimized for subs and just given up on supers. I'd just rock a 9T and magnifier if Sig wasn't absolutely retarded with their pricing, then it's just remembering to flip the gas regulator. Might end up trying the silly nonsense of using a TA50 or PA prism in a QD mount behind a dot or eotech, zero the dot for subs and the prism for supers, use the prism as just a detachable magnifier until loading 110gr  |
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Originally Posted By rb889: I started down the rabbit hole of 9” 5.56 vs 6.75” 300Blk, since both would fit in the bag I’ve got. 300 fits with can attached, 5.56 needs it separated. This is assuming I can actually get my damn hands on a 9” or even 10” barrel/upper… Anyway. 5.56 still wins out in terms of effectiveness once you factor in defensive ammo, since 300blk needs pricer ammunition to be effective, and the best 5.56 options can be had cheaper than decent/mediocre 300Blk. Only real utility I see in the 300 is using subsonic ammo, which would have its own incredibly useful advantages if you ever had to deploy said weapon, since gunfire is like a dinner bell for shitbags. Unfortunately, it seems like there aren’t many good options; Hornady sub-X is relatively affordable, but mediocre. Lehigh does pretty well in testing, but the projectiles are more expensive than full Sub-X cartridges Plus subsonic FMJ is around 70 cents a round. I’m not really a fan of switching between supers and subs in the field, changing your POI and the rifle’s gassing just seems like a bad idea to me. I’m sure I could zero the supers, run and numbers, and get subs on paper to see where the holds are, but damn, that’s a lot of extra headache and stuff to try and remember under stress. Anyone else had this same debate? Cheap 110 300 blk supers out of a 6.75 are going to be more effective than a good 556 bullet out of a 9 inch barrel. I have shot deer with 110 grain varmageddon at 100 yards and found the bullet expanded against the far side skin many times. A 9 inch 556 is not going to that consistently even with good bullets. Varmageddon or vmax loaded 110 ammo is about a buck round ( or reloaded for less than 50 cents a round ), for 2 legged varmints it is extremely effective. As for subs, yes good ones are pricey, when I shoot subs they are just cheap 245 grain cast lead. I do know the drops using it, and I do have some expanding subs. But lets be 100% honest, load your first mag with 5 subs, if the engagement goes past 5 rounds its going to be loud anyways might as well go supers. Zeroed at 100 with supers you will be dead on at 50 and about 6 inches low at 100, close enough for social work. Yes you will pay more for expanding subs but you only need to shoot a few to verify the drops, one box to test and another to keep a few mags topped off. I shoot my 8.3 300 to 300 yards with supers and a 2x prism with no issues, and can hit a 400 more times than not. They may not expand as well at 300 yards as they do at the muzzle, but they will do more than any 556 bullet out of a 9 inch will. As for gassing, none of my ars need gas changes to run supers and subs. I only have the 11.5 lt, so I cant say a spear will run the same super v subs thou. |
"I am gonna laugh my ass off looking out the air vent of the box car watching some of you shot in the head in a ditch when you finally realize it's time to resist." stolen from RR_broccoli
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Originally Posted By rb889: I started down the rabbit hole of 9” 5.56 vs 6.75” 300Blk, since both would fit in the bag I’ve got. 300 fits with can attached, 5.56 needs it separated. This is assuming I can actually get my damn hands on a 9” or even 10” barrel/upper… Anyway. 5.56 still wins out in terms of effectiveness once you factor in defensive ammo, since 300blk needs pricer ammunition to be effective, and the best 5.56 options can be had cheaper than decent/mediocre 300Blk. Only real utility I see in the 300 is using subsonic ammo, which would have its own incredibly useful advantages if you ever had to deploy said weapon, since gunfire is like a dinner bell for shitbags. Unfortunately, it seems like there aren’t many good options; Hornady sub-X is relatively affordable, but mediocre. Lehigh does pretty well in testing, but the projectiles are more expensive than full Sub-X cartridges Plus subsonic FMJ is around 70 cents a round. I’m not really a fan of switching between supers and subs in the field, changing your POI and the rifle’s gassing just seems like a bad idea to me. I’m sure I could zero the supers, run and numbers, and get subs on paper to see where the holds are, but damn, that’s a lot of extra headache and stuff to try and remember under stress. Anyone else had this same debate? I have an ammo can of Sub X factory loads that I have not attempted to shoot since owning a Seekins SBR8 upper that refused to feed them. I will try them out with my Spear LT next time Im at the range, Id rather use them over a 220gr SMK or other subsonic FMJ. I am also looking at the 220gr Nosler Ballistic Tip projectile, does anyone have any feedback regarding the terminal effects of this projectile? |
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Originally Posted By FrankW134: I am also looking at the 220gr Nosler Ballistic Tip projectile, does anyone have any feedback regarding the terminal effects of this projectile? Might as well be a FMJ. |
"I am gonna laugh my ass off looking out the air vent of the box car watching some of you shot in the head in a ditch when you finally realize it's time to resist." stolen from RR_broccoli
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Question: So the 3rd Gen Sig MCX Spear LT (9" barrel) in .300, is designated as the "CSAW" ? Been trying to read up the differences of the models used by the U.S. Military. I am seeing folks say that the 82nd and 101st A/B, CAG and SEALs are utilizing the "CSAW." Thanks. |
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Originally Posted By norshon3: Question: So the 3rd Gen Sig MCX Spear LT (9" barrel) in .300, is designated as the "CSAW" ? Been trying to read up the differences of the models used by the U.S. Military. I am seeing folks say that the 82nd and 101st A/B, CAG and SEALs are utilizing the "CSAW." Thanks. Id be very surprised if I found a CSAW anywhere with 82nd, 101st, or any other big Army unit. From my understanding the CSAW is a SPEAR-LT with a 10.5" 5.56 with proprietary titanium parts that arent available for the public. |
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Originally Posted By FrankW134: Id be very surprised if I found a CSAW anywhere with 82nd, 101st, or any other big Army unit. From my understanding the CSAW is a SPEAR-LT with a 10.5" 5.56 with proprietary titanium parts that arent available for the public. Originally Posted By FrankW134: Originally Posted By norshon3: Question: So the 3rd Gen Sig MCX Spear LT (9" barrel) in .300, is designated as the "CSAW" ? Been trying to read up the differences of the models used by the U.S. Military. I am seeing folks say that the 82nd and 101st A/B, CAG and SEALs are utilizing the "CSAW." Thanks. Id be very surprised if I found a CSAW anywhere with 82nd, 101st, or any other big Army unit. From my understanding the CSAW is a SPEAR-LT with a 10.5" 5.56 with proprietary titanium parts that arent available for the public. Same here, I could see the high speed SOF guys getting gucci stuff, but not any of the larger units, not when they just rolled out the URGI a few years back. Although... I thought they were replacing 10.3" CQBR uppers with the SURG. Whatever happened with that? As for the CSAW, that uses titanium wear parts like the cam path, charging handle roll pins, and feed ramp? Not much weight to be saved, there. Maybe 2 or 3 ounces? Otherwise, I might see some utility for corrosion resistance in saltwater, depending on the titanium and coatings involved. More of a devgru thing than anything else. Gen 3 MCX is overpriced as-is, so adding another $100 or more for a few titanium bits is unnecessary. Now, if the gas block, op rod, and bolt carrier are also titanium, there might be enough weight savings to justify consideration. |
| What light mount is everyone using on their 11.5? I'd like to push a scout light out some so that I can activate the button w/ my thumb, but haven't decided what would be best yet. I think I'm leaning towards just an Arisaka bar, but have a thought in my mind of something that uses the top rail for mounting but cantilevers down the left side a bit and forward. Any suggestions? |
“Always love your country — but never trust your government!" - Robert Novak
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Originally Posted By Paulie771: What light mount is everyone using on their 11.5? I'd like to push a scout light out some so that I can activate the button w/ my thumb, but haven't decided what would be best yet. I think I'm leaning towards just an Arisaka bar, but have a thought in my mind of something that uses the top rail for mounting but cantilevers down the left side a bit and forward. Any suggestions? The Arisaka MCX offset mount works fine for me, mounting a Surefire M600. |
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Originally Posted By Paulie771: What light mount is everyone using on their 11.5? I'd like to push a scout light out some so that I can activate the button w/ my thumb, but haven't decided what would be best yet. I think I'm leaning towards just an Arisaka bar, but have a thought in my mind of something that uses the top rail for mounting but cantilevers down the left side a bit and forward. Any suggestions? Cloud Defensive makes, or at least used to make, such a thing. |
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Originally Posted By SpyHawk: Cloud Defensive makes, or at least used to make, such a thing. Originally Posted By SpyHawk: Originally Posted By Paulie771: What light mount is everyone using on their 11.5? I'd like to push a scout light out some so that I can activate the button w/ my thumb, but haven't decided what would be best yet. I think I'm leaning towards just an Arisaka bar, but have a thought in my mind of something that uses the top rail for mounting but cantilevers down the left side a bit and forward. Any suggestions? Cloud Defensive makes, or at least used to make, such a thing. I just moved some lights around on other builds and went with a straight Arisaka bar under the wrap. Not 100% what I wanted but it suffices. Attached File |
“Always love your country — but never trust your government!" - Robert Novak
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Originally Posted By Paulie771: I just moved some lights around on other builds and went with a straight Arisaka bar under the wrap. Not 100% what I wanted but it suffices. https://www.ar15.com/media/mediaFiles/86616/IMG_4045_jpeg-3810752.JPG Originally Posted By Paulie771: Originally Posted By SpyHawk: Originally Posted By Paulie771: What light mount is everyone using on their 11.5? I'd like to push a scout light out some so that I can activate the button w/ my thumb, but haven't decided what would be best yet. I think I'm leaning towards just an Arisaka bar, but have a thought in my mind of something that uses the top rail for mounting but cantilevers down the left side a bit and forward. Any suggestions? Cloud Defensive makes, or at least used to make, such a thing. I just moved some lights around on other builds and went with a straight Arisaka bar under the wrap. Not 100% what I wanted but it suffices. https://www.ar15.com/media/mediaFiles/86616/IMG_4045_jpeg-3810752.JPG I'm a big fan of the Surefire pro scout models for that, the rotating mount interface basically killed a whole industry of aftermarket scout mounts, lol. But I greatly prefer using the tailcap over a tape switch, I really only use those for lasers. ETA: Any opinions on the 7.75" rattlers in 5.56? Got an opportunity to pick one up for cheap. |
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Originally Posted By Soxfan: Looking for my next suppressor. Anyone using a Huxwrx Flow 556 ti on their spear? Any pros or cons appreciated, thanks! I have two flow 556ks, one on an LMT piston rifle and the other on a PS90. I love them. No gas in my face at all, sounds great at the ear, relatively short and lightweight, and the mounting system is idiot proof… mostly. Cons (sort of): it gets hot FAST. it gets stuck on my rifle so I need a strap wrench to break it free, but better than having it work itself loose tbh It still gets somewhat dirtier than an unsuppressed gun, and there is a very slight backpressure increase (but no gas in my eyes). I had the unsuppressed setting on my gas plug bored out slightly to make it function better. They’re supposed to be loud from the muzzle end - try not to stand in front of it I guess? I don’t have any experience with the 556 ti, but I love my 556ks. |
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Originally Posted By JK-919: I have two flow 556ks, one on an LMT piston rifle and the other on a PS90. I love them. No gas in my face at all, sounds great at the ear, relatively short and lightweight, and the mounting system is idiot proof… mostly. Cons (sort of): it gets hot FAST. it gets stuck on my rifle so I need a strap wrench to break it free, but better than having it work itself loose tbh It still gets somewhat dirtier than an unsuppressed gun, and there is a very slight backpressure increase (but no gas in my eyes). I had the unsuppressed setting on my gas plug bored out slightly to make it function better. They’re supposed to be loud from the muzzle end - try not to stand in front of it I guess? I don’t have any experience with the 556 ti, but I love my 556ks. Originally Posted By JK-919: Originally Posted By Soxfan: Looking for my next suppressor. Anyone using a Huxwrx Flow 556 ti on their spear? Any pros or cons appreciated, thanks! I have two flow 556ks, one on an LMT piston rifle and the other on a PS90. I love them. No gas in my face at all, sounds great at the ear, relatively short and lightweight, and the mounting system is idiot proof… mostly. Cons (sort of): it gets hot FAST. it gets stuck on my rifle so I need a strap wrench to break it free, but better than having it work itself loose tbh It still gets somewhat dirtier than an unsuppressed gun, and there is a very slight backpressure increase (but no gas in my eyes). I had the unsuppressed setting on my gas plug bored out slightly to make it function better. They’re supposed to be loud from the muzzle end - try not to stand in front of it I guess? I don’t have any experience with the 556 ti, but I love my 556ks. Good summation. The Hux needs to be cleaned more frequently than other cans, every 1000 to 3000 rounds, depending on the individual can, some have smaller channels that clog up faster due to variances in 3d printing. As for muzzle blast, any solid walls in front of the shooter will reflect it back at you. Same deal as shooting under an awning. I'm curious if anyone else has had issues finding plan B mounts with Sig's 25 degree taper, Q and Rearden are the two that I've found, but Rearden is always out of stock, and Q... Kinda sucks, since they have no wrench flats. I liked the Rearden mini, it makes a 9" barrel shorter than the 7.75" with the factory flash hider, but it's literally out of stock everywhere. Debating on just using a direct thread to hub adapter, should be fine to just hand tighten that in the same manner, I would think. |
| I had my 11.5 Spear lt cut to 10.9 and rethreaded with a conventional shoulder so I could get away from the Sig taper. The lack of available muzzle devices was infuriating. |
Originally Posted By Steve_T_M:
Political correctness is nothing but left-wing religious fundamentalism.
Political correctness is nothing but left-wing religious fundamentalism.
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Originally Posted By jake03: I had my 11.5 Spear lt cut to 10.9 and rethreaded with a conventional shoulder so I could get away from the Sig taper. The lack of available muzzle devices was infuriating. A number of companies, including Sig, make taper adapters that provides a barrel shoulder so you can use any standard muzzle device. |
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Originally Posted By willi3d: A number of companies, including Sig, make taper adapters that provides a barrel shoulder so you can use any standard muzzle device. Originally Posted By willi3d: Originally Posted By jake03: I had my 11.5 Spear lt cut to 10.9 and rethreaded with a conventional shoulder so I could get away from the Sig taper. The lack of available muzzle devices was infuriating. A number of companies, including Sig, make taper adapters that provides a barrel shoulder so you can use any standard muzzle device. I used the sig taper to mount my surefire 4 prong and RC2. Shipping costs more than the part. |
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Haven't seen this mentioned. Apologies if it's old news. Griffin now offers Taper Mount EZ-Brakes for SIG/Q-style tapered barrels threaded in 1/2x28 and 5/8x24, so the taper adapter is no longer necessary (as long as your can does Plan A). Now I can have my cake and eat it, too. Hope Griffin will expand their SIG-taper offerings but don't know their plans. |
MCX: Generation 3/SPEAR LT (Page 47 of 47)
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