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Old 06-12-2017, 08:32 PM
Elmojo

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SaBRe stock adapter for Charger - product development



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Hi all,
I haven’t been active on here for quite a while, but I’ve been very busy in the rimfire world nonetheless.
I’ve been working on a couple new products, one of which I’d like to show you now, to get general design feedback, but mostly to get the thoughts of the community on just how much demand for this type of product you think there will be.
I’ve been developing the design for quite a while, and I have the prototype complete, but to go to the next step of a limited test run will be quite an investment of money and time, so I thought I better bring it to the rimfire experts here first to see what you folks think.

Anyway, the idea is simple: It’s an adapter that allows the use of a pistol buffer tube or full stock assembly on the newer versions of the Ruger charger pistol that utilize the AR-type grip.
Obviously, if you intend to install a full stock of any sort, you’ll either need to first obtain the proper SBR paperwork or install a 16”+ barrel for ATF compliance.
I’m not going to get further into the finer details of the law at this point, other than to say that as is the case with all firearms, it will be the responsibility of the buyer to ensure that the products are used in accordance with all current applicable laws.

Ok, on to the technical (and fun) stuff.
There are several possible configurations for the system, depending on how many parts you want to change out, how much you want to spend, what your goals (weight/accuracy) are for the platform, etc…

For simplicity in this discussion, I’ll refer to these as conversion “levels”:

Level 1 would be to buy nothing but the SaBre adapter and an AR pistol buffer tube of your choice.
My adapter will come with all required mounting hardware, minus the buffer tube, since there are lots of options out there and everyone has a preference.
This would result in no legal status change for the gun, so no tax stamps. You can use your factory barrel. This is the configuration shown in the 1st photo. Ignore the blue painter’s tape, it’s just there to make the cold tube more comfortable on my cheek when shooting at night.

Level 1a is something I’m experimenting with, which may or may not ever make it to production. It’s the same as level 1, but instead of a standard AR buffer tube, I will include a “stabilizer tube”, as shown in the 2nd photo. Right now it’s simply heavy wall PVC that I’ve turned down on the lathe, threaded, and cut to length. The advantages of this design are that it’s the same exact weight as a standard buffer tube (3.9oz without castle nut), is a bit longer for more flexibility in shooting positions, is a bit cheaper than buying a separate buffer tube, and perhaps above all (for some people) will NOT accept a Sig Brace or AR stock. Why would anyone want this? Because it eliminates any doubt about ATF compliance. Some folks may want to be extra careful in that department. This is the option for you. Also, being plastic, it’s easy to shorten the tube with simple tools. I’m also searching for end plugs, which would make it watertight storage for ammo, a cleaning kit, etc… If you want a version that WILL accept a Sig Brace, that’s super easy, I’ll just use different diameter pipe or turn it down on the lathe, no problem.

Level 2 is a moderate step beyond Level 1, with the addition of replacing the barrel as well. The buyer will have their choice of pretty much any aftermarket Charger barrel, but if you’re going to bother replace it, you should gain something, such as increased accuracy, shorter overall length or lighter weight. For example, the 3rd photo shows a custom Carbon Fiber barrel that I manufacture in-house. Those may be available as a “combo” deal at some point, I haven’t decided yet. They are handmade and take a long time, so I wouldn’t want to hold things up waiting on barrels.

Level 3 would be to buy a SaBRe adapter, carbine buffer tube, carbine stock and barrel of 16”+.
This would result in a rifle, so still no legal status change, no tax stamp. You’d lose a bit of maneuverability due to the extra weight and barrel length, but you’d gain a bit of accuracy and you’d be able to use a full stock without SBR hassles, so it’s a trade-off.
This configuration is shown in the 4th photo. I’m using a standard 18.5” Ruger factory taper barrel in this example because I had one lying around, but of course you can use any barrel that will fit, including the 16” version of my Carbon barrels, which weigh about 1/2 of what the factory taper barrel does and less than 1/3 of the common bull barrel options, so the extra weight isn’t a huge issue.
PLEASE NOTE: If you use this configuration, you MUST install the barrel BEFORE you install the SaBRe adapter and stock or you will be manufacturing an SBR and will be in violation.
You may have to open up the barrel channel in the factory Charger stock if you use a full bull barrel. The taper barrel fits without modifications. My Carbon barrel requires a little work with some sandpaper and a dowel, but nowhere near as much as a true Bull barrel.

Level 4 would be the ‘Holy Grail’, a full SBR build. This would consist of the SaBRe adapter, carbine buffer tube, and carbine stock. Of course you’d need to file and receive back your ATF paperwork before any of these parts are installed. You can use the factory barrel or an aftermarket barrel of any length. Honestly, if you’re going this route, you’re most likely getting a suppressor as well, so you’re probably swapping out the barrel. This can get expensive quick, but oh man I bet it would look and shoot awesome. Sadly, I don’t have SBR paperwork on mine, so I can’t test it, but I do have a friend with a suppressor who brought his over for me to try and it rocks hard on my 8.25” Carbon barrel with CCI Standard Velocity ammo. The bolt cycling was by far the loudest sound, followed closely by the bullet striking the target.

As far as the SaBRe adapter itself, you can see that basic idea from the photos. It’s fundamental goal is simply to allow the attachment of any AR-compatible buffer tube to the Charger. However, this is nowhere as easy as it sounds. The photos you see are of prototype #9, design #14. That means that it went through 14 design changes, 9 of which actually got built before landing on this one.
One of my key goals for this whole thing was that the adapter not require modifying the base gun in any way, and I’ve finally achieved that. The adapter kit will come with all the hardware required for installation, including a replacement through-bolt, which holds the grip trunion in place. This means that I can install or uninstall the SaBre and its associated buffer/stock assembly in maybe 3 minutes, and put the gun right back to factory condition. I can swap the SaBRe assembly and barrel in about 5 minutes.
I felt this was important, since laws change, as do the needs and desires of the shooter from day to day.
For example, say you have it set up with the 18.5” taper barrel and a full stock like in the 2nd photo, because you are hunting squirrels with it. The next weekend, you decide to go backpacking in a remote area and would like to have a little plinker along for the ride, but there’s no way to haul that roughly 34.5” package up and down the trails. No problem! Take a couple Allen wrenches and 5 minutes, and convert it either all the way back to the factory pistol configuration, or like you see in the 1st photo, if you have a pistol buffer and shorter barrel.

See? Flexibility!
I actually really like the short barrel with the buffer.
That type of setup is kinda useless on an AR, which weighs too much and recoils just enough to toss your aim all over.
However, on this platform, especially with the short (light!) barrel, a simple cheek weld is plenty to keep this stable. I can shoot this one that way almost as accurately as with the longer barrel and full stock.

The one you see in the photos is a 3D printed prototype with really rough hand fitted top and bottom plates. The final product is designed to be all aluminum CNC machined, but otherwise pretty much the same design. The idea is to keep it as simple and affordable as possible. I’m still working out the supply chain issues and material costs, so I don’t have projected prices quite yet, but I’m thinking something in the $99-129 range for the adapter, plus maybe some various “packages” for those who’d prefer not to have to buy their own buffers, stocks, barrels, etc…

Here’s some of the size and weight information I collected while working on this, for comparison:
Receiver assembly with bolt and top rail: 1lb 3.5oz (19.5oz)
Factory 10.0” Charger barrel: 1lb 1.9oz (17.9oz)
Custom 8.25” Carbon tensioned Charger barrel: 9.5oz
Factory 18.5” taper barrel (with sights): 1lb 13.1oz (29.1oz)
Custom 16” Carbon tensioned rifle barrel: ~1lb (16oz)
Complete gun in heaviest “rifle” config without mag: 4lbs 9.7oz (73.7oz)

Ok, that’s more than enough for now. Tell me what you think.
Is this something you would buy?
Why or why not?
If not, what would need to change before you would?
If so, which configuration/Level most appeals to you?
If I go to the next step and commission a limited production run, I'll be making a fairly expensive leap, so I'd like to know I'm producing a product the community actually wants.
Thanks in advance for any input!
-Mike
Attached Images
File Type: jpg lvl1.jpg (233.3 KB, 8 views)
File Type: jpg lvl1a.jpg (243.1 KB, 4 views)
File Type: jpg lvl2.jpg (245.1 KB, 3 views)
File Type: jpg lvl3.jpg (483.4 KB, 3 views)

Last edited by Elmojo; 06-12-2017 at 08:34 PM. Reason: typo
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  #2  
Old 06-13-2017, 08:20 AM
Indigo22's Avatar
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I am currently looking for a good used charger and have plans along those lines. I would be willing to pay in the $89-$99 range above that I would likely go another route. I do like your idea of not having to modify the stock.
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Old 06-13-2017, 10:05 AM
Elmojo

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Thanks, for the feedback!
I'd love to keep it down under $100, it will just depend on how much the materials, tooling setup, and machining ends up costing.
As with most manufacturing, volume is king, so the larger run I can do, the lower I can get the price. If I do a run of say 10, they will be way too expensive, since those would qualify as basically custom one-offs.
I've talked to a couple machine shops, and it looks like a batch of 25-50 is about the low end of what they consider "worth it", and where the prices start to get reasonable for custom machining.

I may even do a few myself as pre-release, or early adopter versions, whatever you want to call them. I have the equipment to make everything in-house, it will just take longer and the results won't be as polished or professional looking as if I can get it all CNC'd and just do the final hand fitting and finishing myself.

Anyone else have thoughts?
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