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Posted: 5/31/2025 4:37:49 AM EDT
[Last Edit: Namsag][Edited]
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If anyone who see's this post has any information on usage, their experience, or still has one burried in their safe, jump in and share on this RAS 12. This RAS 12 may not be known but by a few on this site. Intrepid Tactical Solutions was the manufacturer. It was introduced in 2013 and sold as a complete shotgun or you could get just the upper. It is designed around the DPS 25 lower (308 lower) That is the lower you need for this to work with it. An AR 10 will not work. So take your most common .308 lower, set this upper on it and push in the pins. They came with a modified Magpul .308 magazine, the follower and feed lips were modified. The actual body of the magazine was also modified including the exit point of the round. It was lowered and reshaped. The two main ribs runnning inside the length of the magazine itself were ground out of the magazine. Poorly done by hand. This is a major drawback as these modified magazines were not marketed to my knowledge. The biggest draw back to this 12 ga upper? It used proprietary amunition, a polymer rimless design. The idea was actually pretty good. A 12 ga round treated like a regular rifle round. The ammo was expensive and barely available. It only came in 00 Buck to my knowledge. I have a bunch of this ammo I picked up once Intrepid was finished. Expensive! So what I'm going to do is break it down so you can see what it is. It's a big bore 12 gauge AR. This is the first or one of the first to go down this path, a 12 gauge AR. I have several of these uppers, new in the box so I thought why not break one out and see what it is, how its made, can it be SBS'ed? It has an 18 inch barrel, a 9 inch long bolt carrier that weigh's half a ton. A few pics to get started and hoping some of you might have useful information on your experience or what you might know of the RAS 12.            |
I remember when those came out. Saw the first one at the 2013 SHOT Show (and I was wearing a shirt with the logo of my employer's business  which caused somewhat of a “second look”). The proprietary ammo obviously limited its appeal to the mass market. |
Steve Rose - RAS
"Let your gun therefore be the constant companion of your walks"
Thomas Jefferson - 1785
"Let your gun therefore be the constant companion of your walks"
Thomas Jefferson - 1785
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This RAS upper is pretty easy to disassemble and work on. I pulled the gas piston/op rod out to measure it and get its weight. It's length is quite long, really long. Over 12 5/8 inches. Weight is 2.75 ounces. That piston gets 2 orange high temp O-rings on it. They were stuck to the gas block, destroyed during removal. The bolt and carrier are pretty heavy. 17.1 ounces. This upper was probably built in 2013 or 2014 so no surprise on the stock O-rings. More to come    |
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Today is March 16th and I decided to stop looking at this thing and do something. Kind of formulating a plan today and did decide on the length of the barrel. Almost! It's a 9" or 10" The barrel on this thing is heavy and thick walled for sure. 18" Just ouside the receiver (1.5" from breach opening) it is 1.170 diameter. At the 9" mark, it is still 1.060 diameter. I could put an 8ga choke in this! Does that even exist? Thats a wall thickness of about 165 thousandths of an inch, nearly 3/16th of an inch per side. It will get a choke. Most likely a Rem choke as I have a lots of Rem chokes. The ammo is buckshot, 1200FPS with a 1.1oz load, 9 pellets. Pretty much a standard load and the only ammo ever made for the RAS 12. It's a ball tipped rimless polymer shotshell of propriatary design. It works really well. So what is on the list to do to get started? Get permission from Uncle Sam to do this. Might be an issue for me as I want to use an 80% lower I finished for testing. I might want to alter the feed area of this lower, to enhance the feeding if needed. I have other DPMS lowers already stamped that I can use as well. Cut the barrel to the desired length. A bit longer for finishing later. About the 9 1/8" mark is where the gas block diameter started on the original barrel. Diameter of .930 Good place to cut. Original gas ports were located 10 3/4" down the barrel leaving 7" of barrel for dwell time. 4 gas ports will be used and start 4 1/2" from the breach. That will leave over 4" of barrel after the ports. Good dwell time. The gas block. The factory block is 2.600 long. Requires that much barrel to mount it. I may do a custom version needing about half that much length. Adds other benefits, adds creation issue. Make a new piston. Original piston diameter will be kept. Op rod will be less than half original length. More shortly and pictures. |
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I have no clue on how compatible it is, but check out the JTS M12AR. I just picked one up for $150 from PSA and want to SBS it. Mark Serbu did a review on it and I saw a SBS version in this forum which put it on my radar. Maybe the mags could work for you at the minimum. It is a piston AR 12ga. that looks to me like it was, to put it nicely, inspired by this upper. It isn't compatible with most AR15 or AR10 parts, but it does use some like the fire control group. The buffer tube is a fixed carbine looking thing and can be switched out for an AR compatible one. |
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So here we go with some more pictures and some more details. This is what I'm starting with. An 80% DPMS 25 lower I finished some years ago. This RAS upper fits really nice to the lower. Not line to line so to speak but very nice. The lower has no finish except for the abrasive tumbler it came out of. It has a quality drop in trigger with about 4 lb pull so just right for this project. Here it is with the 18" stock barrel.  Barrel length will be 9 inches which is just at the step in the barrel. I have encountered the first problem.....I've been unable to remove the barrel nut. It is really tight. I can't tell if a locking compound was used as the threads are clean. I put the upper in a fixture I have and went after it pretty hard. The tool I have is not a full circle and it kept wanting to go over the top of the lugs. I could see the receiver twisting slightly. Can't break this one as there are no replacements. It's somewhat propriarty because of the custom round it fires. I'm not 100% sure its the correct tool. It just feels too loose and doesn't want to stay engaged on the nut. This nut has 20 lugs. Measures out to be a 1.5 inch circle the lugs are on. There are different versions of the 20 lug pattern wrenches. There are AR10 nuts with 22 and even 24 lugs. None of the barrel wrenches I looked at list how many lugs they have. No point in buying another not knowing the lug count. I used some Break Free and even applied some torch heat. Just wouldn't give it up. Having a custom wrench made to fit this nut and we'll have another go at it.  So these original ports will be cut off. Their 10 3/4 inches down the barrel. Note their size.  I want to talk about the magazine that came with the upper and a possible replacement. The mag supplied is a highly modified Magpul 20rd .308. Lots of modifications. The top of the feed lips shortened so the bolt can pass over without hitting, about .020 or so. Feed lips length has been shortened as well to allow the 12 ga round more room to exit the mag. The profile of the mag altered at the round exit point. Lowered and cut back. The follower milled out I think to allow more room for the shell but still maintain its job to retain/stop the follower. The actual guide ribs in the mag that run from top to bottom, each side, have been ground out, flush or less with the sides of the mag. Thats a lot of work if I want to create more magazines. So I grabed a C Products .308 20rd magazine I had and made some evaluations of it campared to the Magpul. Some comparison pics of the mags. The C products is not modified and the Magpul is. The C Products left and the Magpul right.       Here they are with a single propriatary RAS 12 round loaded up. Nearly identical. The Magpul is exibiting some left side bias because of its original intent. The area right under the nose of the round will get a small circular releif so the bullet nose and its case pass out of the mag without snagging. This will be around .010 to .015 max depth, to match the radius of the round itself. Will be very small. Also the C Products mag has ribs going down the inside of the mag as well. I loaded up 4 rounds in the mag and there is a slight drag on the shells. It may work like that of maybe need the slightest relief, maybe two or three thousandths per side. Easy to do with a hand belt sander/profiler. Same issue with the feed lips, a bit too tall. Two options here. Take a little off the top of the lips or a little off the slot that sets the depth of the mag. This will lower the mag by whatever I remove. The bolt will easily pick up the next round as I already gave it a dry run. Note. The round in the CP mag fits better, moves easier, and feels more secure. Steel lips VS polymer lips. It's a plus on this one. It looks to be a viable replacement for the Magpul with a lot less work to do and they are great magazines.   The lower receiver will get some minor modifications at the feed site. The front of the magwell. The cross bracing of the receiver needs to have a small relief created where the arrow is in pic 1. With the upper mounted, you can see how the height of the bracing just slightly interferes with the round moving into the chamber. Pic 2 With the C Products mag installed at its stock positioning, it also interferes with the round moving into the chamber. If I drop the mag about .010 lower, that interference probably will be gone. These are just the details I've discovered so far. There may be more as I move thru this creation. Going to do some of this work before returning with more pics. Stay tuned.    |
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Originally Posted By ihon: I have no clue on how compatible it is, but check out the JTS M12AR. I just picked one up for $150 from PSA and want to SBS it. Mark Serbu did a review on it and I saw a SBS version in this forum which put it on my radar. Maybe the mags could work for you at the minimum. It is a piston AR 12ga. that looks to me like it was, to put it nicely, inspired by this upper. It isn't compatible with most AR15 or AR10 parts, but it does use some like the fire control group. The buffer tube is a fixed carbine looking thing and can be switched out for an AR compatible one. Here is what the mag looks like for the JTSM12AR. Looks OK but I'm a bit concerned with the very short feed lips. Since there is no rim on these propriatary shells, the back of the shell has a reduced diameter. that leaves a short amount of the existing feed lips to retain the shell. Actually not very much. This pic is from GritrSports who has the mag for $17.99. Maybe just go ahead and order a couple and see. Thanks for the heads up.  |
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Originally Posted By swampfoxoutdoors: Just think with 3d printing rapidly expanding you can start rolling your own rounds. Yes, I had contemplated that after printing a bunch V3 adapters. The rounds originally cost $3 a round. Way too much. The only way would be to comercially print them. Thats way more expensive than $3 a round. These are reloadable. Where to find the bullet nose? Guess I could create the nose. Have to give that some real thought. |
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Another update. The barrel has now been cut to length, 9". Barrel is finished as far as lathe work. Came out very nice. Barrel gas block diameter is .935. The rest of the barrel is .930. There will be 4X .082 gas ports about 6" from the muzzle and that location will net some good dwell time. The gas piston and op rod have been shortened but not to the finished length. About 1/4 inch shorter is needed. It's shaft also needs to be turned down to enter the upper receiver port. The shaft is .250 now and will need to be .187 about 2/3 of its length. Receiver hole is .196 About .004 clearence all around the rod. Keeping it pretty tight. Straight rod and tight clearance keeps the energy at it's max. The grip is a FAB defense 43. FDE just for the pictures. The receiver plug is used to hold the bolt carrier completely forward for piston measurements. C Products 10rd .308 magazine inserted (holds 5 rounds) It will be modified somewhat for use in this SBS. Going to attempt to make the handguard rather then to modify the original. Something different. Wish me luck. Needs gas port holes, magizine modified, piston fitted, and a buffer tube thought out and installed with buttstock, then for the testing. It has a standard forcing cone I may lengthen to about 1 inch. No plans for a choke at this point.      
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Originally Posted By ihon: The JTS M12AR mags will not readily fit in an AR-10 mag well. I tried it in my POF Rouge and it's a no go. The metal clip on the top back of the mag is too wide. The front of the JTS mag also has a plastic catch that would need to be filed away. I ordered two of them because they were pretty cheap. They are now paper weights. As you say, the metal feed lips are too wide to fit in an AR .308 lower. Other issues as well. They are propriatary and will only fit in the JTS magwell. I don't think convertable to any other platform. |
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I had to decide what receiver extension I needed to run on this project. Could'nt find any info on what has been used or tried. A carbine tube or a .308 tube. (A5) Difference being 7" inside for the carbine and 7 3/4" inside for the .308 tube. Here is the plan. Start with an A5 tube and a Springco yellow spring. Their weakest spring. I misplaced the spring that came with this upper and I have read it is a lighter spring. Use a standard 2.5" buffer and a 3/4 inch spacer for just the buffer. Mount it in the back of the tube. The spring will use all of the 7 3/4 tube. Yes, I could use a 3.25 inch buffer but I have a 2.5" Kynshot hydralic buffer I want to start with. This will prevent L2 coil bind and yet prevent overtravel on the bolt carrier. The yellow spring is the least power spring Springco makes but it's coil bind is longer than 2.5 inches. So allowing the spring 3/4 inch more room, that problem gets eliminated but still have the lighter spring to start with. I will have the option to move to stronger springs if needed with this set up. I ordered up a couple of Magpul 10 position, mil spec fit, enhanced tubes, SR25/110mm 7 3/4 long. This is where the starting point will be. Should have them by the end of the week. |
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Update. Further down the path to completion. As it looks today. Made a few changes. Now pretty much all of the equipment is present and baseline work complete. Exception custom handguard. The plan is to make one  The BCG extends 4" out of the upper receiver. It's a heavy BCG. The yellow buffer spring is installed and the KynShot buffer. Buffer is 3.25 in length and weighs 5ozs. Perfect for the 7.75 tube. The 10 position buffer tube but can only use 8 holes because of the buttstock length. The Fortis K1 System (tapered) castle nut-LE Lightweight Enhanced AR15 End Plate with QD which locks on with the castle nut. Shown open and installed for the info. Excellent product. About $40. The KynShot hydralic buffer. RG5005. Just over $100. The Elftman Trigger neatly installed. Not sure if it will have enough oomph! And the piston op rod combo cut to just over 6". 1/4 diameter rod. Still needs to be fitted/shortened a bit more. I was going to turn it down but decided to open the hole in the receiver to fit the rod instead. (The rod seen in the gas block and receiver is a close fit to hole straight for measuring purposes)          
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I was looking for a tool to assist with setting up these 12ga uppers, drilling the ports accurately, etc. I came across this VISM Pro Series AR10 Upper R Receiver block. This tool solves most if not all of the needed support that will help reduce set-up time and accuracy. It securely locks down the AR10 uppers used on these 12ga AR uppers. It's a vise block that will very securley hold the upper vertical and solidly, especially for the drilling of the gas ports. Has notches for the uppers lugs, pins thru the take down and pivot holes. I would have liked the block that locks into the barrel extension but these 12ga's are all a bit different. Not a standard bolt interface. It will secure well enough for torquing the barrel nuts without twisting the upper. It's a great purchase for me because of the large number if AR12 platform shotguns I have. Also purchassed the AR15 version as well.       The laser/flashlight combo piece on top is a Votatu product, a P9L-G. Green laser and light combo. Well made, finished nicely, high powered green laser, and a strong flashlight. Rechargeble so no batteries. All in a nicely, well thought out package. Looks good too! Great controls on the back. I have one of their red dots on a shotgun and it has been perfect and withstands the 12ga recoil.     |
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Update: Found some time to get to the shop and finally drill the gas ports. I used the Vism fixture just purchassed. It was a breeze to dial in the barrel and drill the ports. Barrel diameter at the port location is .935 inches. I used an edge finder to locate the barrels center and the distance from the front of the gas block when mounted. That distance is 1.855 inches from the front of the block to the gas port hole in the block. Done in 10 minutes because of the Vism block. I upped the hole size from the original thought of .080 to .096 mainly because of the 17 ounce bolt carrier. HEAVY! Using a Magpul 7 3/4 buffer tube, a 5oz Kynshot 3 1/4 buffer. Buffer tube is super smooth inside which will help cut down buffer noise. Still no design on the handguard to cover the very tall gas block. I cut the original handguard off and installed the short piece that clamps to the upper receiver. There is a .010 clearance between the gas block and the stubby handguard. The handguard will be made of several pieces, all tied together solidly. Or, no handguard at all, just a forward grip mount on the bottom exposing the gas block completely. The skeleton look!!! It's ready for it very first test. I'm excited because this is a first with an unusual piece that's now history. I will say one thing I have been quite impressed with. The fit and finish of this upper, from the manufacturer, is top notch. Beautifully done. Here's a look at the finished gas ports showing their location and the stub handguard segment.     |
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