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Posted: 11/22/2025 12:10:56 AM EDT
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I have FM 15 in 12.5" configuration, I was going to throw on a folding brace until i stumbled accross the new bull pup conversion kits made for this upper. Spent hours watching youtube review videos, and it seems the Scy has the popular vote due to lower cost, and not needing a FFL transfer(ARTB FM). I wanted to see if there was any expierence owners of these kits who could answer the following questions for me. I'm not interested in the SRU SARB-15, since it has the buffer extension on the back, which I won't be using. My aim is for the shortest OAL. -Which conversion kit weighs the least, or would it be the ARTB FM lower. -Having big hands, which kit provides the bigger gap between the pistol grip and installed mag? -Anyone using a Franklin Armory binary trigger set with one of these kits? |
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Originally Posted By cj3waker: No experience with them but I've window shopped then pretty well. ARTB is going to be the lightest. It also has about an inch shorter LOP and looks like more room between magwell and grip Same here. But fundamentally since the ARTB is a complete lower and not some kind of kit you install onto your lower, it will always be the lightest, smallest, and most reliable/robust with the fewest failure points. If I were to go for a bullpup FM upper, I think that's the one I would choose. |
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I got a A3 triad as I also didn't want the extended buffer tube length on the SRU unit. It also helps that I bought mine used locally at a discount. The seller included the AR lower as he didn't want to disassemble it. I still had to switch out lowers as I have a spare SBR lower for my 11.5" FM-15 upper. I really like it and it is very well designed. I also think it is one of the better looking kits as well. The Rise trigger is excellent. I'm tempted to get a FM .300 upper for it. Although I may get a K&M ARTB FM lower for it to have something new. The only thing that I don't like about the A3 is its plastic. There is a very narrow part between the pistol grip and mag well that doesn't inspire confidence. When its pinned to the upper, it feels solid. But it's pretty flexible without it and I can see it being a failure point. I really wish it was reinforced with metal or thicker plastic. But I haven't seen any post about that, so maybe it isn't an issue. I also have a Keltec RBD, so I guess I can't complain about plastic guns. I may try the K&M kit next with an FM .300 upper. There are a couple of things I do like about the K&M ARTB FM. First is it is all aluminum, so it should be pretty durable. All the other kits are plastic shells that clamp around AR uppers & lowers. The second is that it is a braced kit if you're doing a pistol vs a SBR. I put my SBR in my A3 kit, so not a factor for me. You can get pistol versions of the A3, but the K&M looks cleaner to me. I realize that SBR lowers will radically change with the tax going away. But as is, it can run as a pistol with a pretty well thought out brace from the looks of it. It does look pretty solid. You also don't have to add a lower to the K&M kit. It's not a big expense, mine is an Anderson lower. But does narrow the price difference a little ($50-150), although most have a spare AR lower sitting around. My other SBR lowers were all non-milspec patterns (Quentin billet, 17 Design folder, QC10 9mm, etc.) and won't work with the shell kits without mods. As a side note. Before I got my A3 kit, I actually bought Keltec RBD ($600ish) for similar money to a brand new A3 kit that isn't on sale. If you didn't already have the upper, it's more cost effective way to get a bullpup. I bet the durability is the same as the kits, which are also bolt together plastic shells. |
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I have an rdb-d that I rigged a zhukov forened on and got the lightweight bolt assembly for. It's now a pretty light gun with decent ergos (better than OEM anyway) and I really like it. Anyone that has one can probably relate to the idea that it's a great gun, but could also be so much better. I have no need for another gun, let alone another "do all rifle" but I think the 18" FM on the ARTB could truly be that. At under 5lbs with good ergos, rail estate, and a real free float option it seems like the ultimate bullpup. The only thing I would want different is a longer rail. If FM would make a 17" rail on the 18" variant I might just bite the bullet. The handguard length looks pretty similar to what I have on my RDB, and while it would undoubtedly be better seeing it's a real handguard I wouldn't mind a few more inches... 
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I also have a 18" Keltec RDB, it's my small game hunting rife, HTA 10/22 bullpup, and the P80 Meta bullpup for my glock clones. Big fan of bull pups. I'm leaning toward the ARTB since I also have bufferless AR9 and AR45 from BCA which look like they would work and swap over easily. |
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| I have a micro bullpup I built with an ARTB. It’s probably one of the finest triggers I’ve felt. Mine uses a .300 BLK upper in 9” - the whole package is about 3lbs. 10oz. There’s no comparison. The ARTB is crafted as a complete gun, not an accessory. Worth every penny. |
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Originally Posted By Skullsoldier: I have a micro bullpup I built with an ARTB. It’s probably one of the finest triggers I’ve felt. Mine uses a .300 BLK upper in 9” - the whole package is about 3lbs. 10oz. There’s no comparison. The ARTB is crafted as a complete gun, not an accessory. Worth every penny. Do you run any pad on the end? I was wondering if there was an option for one |
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This thread is my first time reading about the K&M ARTB. It looks absolutely awesome! Love how they designed it as a pistol and have the shortest possible OAL. I've been really intrigued by the bullpup kits but every time I look closely at the pics and see all those bolts in the side or small plastic parts I decide they just look too fragile. I might actually buy the K&M lower. Only concern would be reliability and durability of the FM upper itself. |
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Originally Posted By rerun1: Do you run any pad on the end? I was wondering if there was an option for one Originally Posted By rerun1: Originally Posted By Skullsoldier: I have a micro bullpup I built with an ARTB. It’s probably one of the finest triggers I’ve felt. Mine uses a .300 BLK upper in 9” - the whole package is about 3lbs. 10oz. There’s no comparison. The ARTB is crafted as a complete gun, not an accessory. Worth every penny. Do you run any pad on the end? I was wondering if there was an option for one I have mine set up as a pistol. |
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I had alot of fitment issues with the Triad kit it's pretty much a paperweight at this point. Milspec lower compatibility vs dedicated lower comes at its price. I wish I'd known about the ARTB before purchasing all conversion kits including the SARB. Originally Posted By shenendoah_rifleman: I've been really intrigued by the bullpup kits but every time I look closely at the pics and see all those bolts in the side or small plastic parts I decide they just look too fragile. I might actually buy the K&M lower. Only concern would be reliability and durability of the FM upper itself. Once assembled most kits are very solid, the triad being the better quality but yes there is some fragility to all clamshell kits. The weak link in the FM upper if any would be the buffer after a few thousand rounds, maybe the bolt. |
I have an ARTB. It has a phenomenal trigger, not just for a bullpup, but for any gun. I have an 11.25" upper on it and I think I'm going to swap it for a 16". The 11.25" is just too short, it's smaller than a P90. I'm using an A3 Industries cheek rest and carry handle riser. |
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Originally Posted By November5: I have an ARTB. It has a phenomenal trigger, not just for a bullpup, but for any gun. I have an 11.25" upper on it and I think I'm going to swap it for a 16". The 11.25" is just too short, it's smaller than a P90. I'm using an A3 Industries cheek rest and carry handle riser. https://www.ar15.com/media/mediaFiles/173129/Photoroom_20251019_170107-3644556.jpg That looks sick! But yeah no rail space at all with an 11" bullpup, it basically needs to be a bare bones PDW setup if you want to go that short. Does it take normal AR pattern safeties? |
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Originally Posted By shenendoah_rifleman: That looks sick! But yeah no rail space at all with an 11" bullpup, it basically needs to be a bare bones PDW setup if you want to go that short. Does it take normal AR pattern safeties? Originally Posted By shenendoah_rifleman: Originally Posted By November5: I have an ARTB. It has a phenomenal trigger, not just for a bullpup, but for any gun. I have an 11.25" upper on it and I think I'm going to swap it for a 16". The 11.25" is just too short, it's smaller than a P90. I'm using an A3 Industries cheek rest and carry handle riser. https://www.ar15.com/media/mediaFiles/173129/Photoroom_20251019_170107-3644556.jpg That looks sick! But yeah no rail space at all with an 11" bullpup, it basically needs to be a bare bones PDW setup if you want to go that short. Does it take normal AR pattern safeties? |
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Originally Posted By MtnRoamer: This. How'd y'all get yours? Originally Posted By MtnRoamer: Originally Posted By LeeTN: How does one actually buy the ARTB? It's not on the site's order page. This. How'd y'all get yours? |
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Originally Posted By LeeTN: So did I. Not a word. I'll try again. ETA: That makes three times . Originally Posted By LeeTN: Originally Posted By November5: I signed up for email notifications for the ARTB on K&M's site. So did I. Not a word. I'll try again. ETA: That makes three times . |
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Originally Posted By November5: . . . . Have you checked to make sure his emails aren't going to your junk folder? Originally Posted By November5: . . . . Have you checked to make sure his emails aren't going to your junk folder? Yep: zilch. Originally Posted By November5: Try shooting him an email . . . . Just did. |
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Originally Posted By November5: I have an ARTB. It has a phenomenal trigger, not just for a bullpup, but for any gun. I have an 11.25" upper on it and I think I'm going to swap it for a 16". The 11.25" is just too short, it's smaller than a P90. I'm using an A3 Industries cheek rest and carry handle riser. https://www.ar15.com/media/mediaFiles/173129/Photoroom_20251019_170107-3644556.jpg Are you running that as a pistol or have you SBR'd it? |
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Originally Posted By LeeTN: Are you running that as a pistol or have you SBR'd it? Originally Posted By LeeTN: Originally Posted By November5: I have an ARTB. It has a phenomenal trigger, not just for a bullpup, but for any gun. I have an 11.25" upper on it and I think I'm going to swap it for a 16". The 11.25" is just too short, it's smaller than a P90. I'm using an A3 Industries cheek rest and carry handle riser. https://www.ar15.com/media/mediaFiles/173129/Photoroom_20251019_170107-3644556.jpg Are you running that as a pistol or have you SBR'd it? |
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Originally Posted By Mustang17: The ARTB looks nice but the mag release location looks like a pain  The mag releases (it's ambidextrous) are in the usual locations for AR15 lowers. If you're looking for a release near the primary (front) trigger, I doubt you'll find one. That would just be one long linkage too many for a conversion kit. You might find a purpose-built bullpup that has one but I doubt that, too. ETA: seems that the Tavor has a forward mag release, but it's supposedly complex. |
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