I was just looking over a thread on the new C20 (Colt Canada's take on Colt's CM/LE-901) which led me to look into the CM/LE-901 some more. It's a damn cool concept and I'd love to get one but I really have no interest in any more restricted firearms (especially not something .308/6.5 creed sized). It got me thinking about applying the same concept to a NR .308 lower like a Stag-10 (or even BCL-102, I guess). A smaller upper receiver designed for the calibers based on the .223 parent cartridge and a mag block to allow you to use Stanag mags. Obviously convincing someone that it's worthwhile to design/manufacture is a pretty big hurdle but would there be any legal issues with doing something like that? Seems to me that since the lower is what is concerned "the firearm" there really wouldn't be any issues in doing this?
Multi-caliber Stag-10 a la Colt LE/CM-901
- Thread starter rugbydave
- Start date
- Location
- WMU248 near Edmonton
oh I think that this is slippery slopes
If the AR15 upper fits on the lower then the firearms lab may just declare the lower now an AR15 variant
If the AR15 upper fits on the lower then the firearms lab may just declare the lower now an AR15 variant
rifleman762
CGN Ultra frequent flyer
- Location
- Southern Alberta
It would have to be a custom upper in order to fit on the AR-10 sized lower. No way would it fit on an AR15 lower.
I think it would be technically feasible but a lot of work. Including a custom bolt/barrel/BCG (maybe you could make AR15 sized parts work?). If you had to pay for the machine time for a one-off, you may as well buy an ATRS receiver set. And it's doubtful that there is enough of a market for mass production - the Canadian market is just too small (how many people want a 10 lb 5.56 rifle?) and it wouldn't sell in the US where they would just buy a complete AR15 for less than the price of the conversion upper.
If Canada had laws limiting the number of rifles you can own like in some European countries, I could see a conversion being popular. As it stands, just buy/build another gun
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It would have to be a custom upper in order to fit on the AR-10 sized lower. No way would it fit on an AR15 lower.
I think it would be technically feasible but a lot of work. Including a custom bolt/barrel/BCG (maybe you could make AR15 sized parts work?). If you had to pay for the machine time for a one-off, you may as well buy an ATRS receiver set. And it's doubtful that there is enough of a market for mass production - the Canadian market is just too small (how many people want a 10 lb 5.56 rifle?) and it wouldn't sell in the US where they would just buy a complete AR15 for less than the price of the conversion upper.
If Canada had laws limiting the number of rifles you can own like in some European countries, I could see a conversion being popular. As it stands, just buy/build another gun
Yeah, I realize it would be a ton of work. I figured you'd design the upper to take all AR-15 parts, barrel, bcg, hand guard, etc. Just re-design it so the pins line up with the lower. Like you said, no way would it fit an AR-15 lower. The upside would be that since the upper isn't a firearm, no need for FRT nonsense or dealing with the lab. Plus there must be a ton of Stags out in the wild right now. I also don't think it would be all that much heavier than a similarly setup AR since really, only the lower would be heavier and I don't think there's a huge weight difference between an AR-10 and AR-15 lower? Most of the extra weight is in the bigger bcg, I would think.
Another concept could be a modified bcg that would work with a mag block so could run stanag mags and it would feed .223?
The point is more to have a multi-cal lower (that lots of people already own) that can do .308 and .223 parent cases. Not really to run hot-rodded .22 cals
The CM901 idea wont' work with a STAG or your typical AR10 type lower - pay attention to how the CM901 front pivot pin is located to accommodate the conversion kit. This is because there is not enough meat for the lower push pin ears to accommodate both the upper lug and the conversion kit, that's why Colt moved it down.
I think the easiest route to go would be to get a normal bolt but with the bolt face for 223 sized cases (which I can not find) and a Mag well block or something. This way no dimensions are changed except the bolt face and a mag well adapter could easily be 3d printed
I don’t see why you couldn’t do it. The hardest part I could see is the bolt and the magwell conversion.
Use an existing stag 10 upper, have a custom barrel turned in 223 but with the 308 DPMS pattern barrel extension, have someone design and do up a 3D printed magwell conversion block, and then use a lightweight 308 bolt carrier. Again, you’ll have to find or convince someone to machine a 308 sized bolt with a 223 head.
Costly and time consuming but in theory, very doable.
Use an existing stag 10 upper, have a custom barrel turned in 223 but with the 308 DPMS pattern barrel extension, have someone design and do up a 3D printed magwell conversion block, and then use a lightweight 308 bolt carrier. Again, you’ll have to find or convince someone to machine a 308 sized bolt with a 223 head.
Costly and time consuming but in theory, very doable.
Yeah,I just looked at that. I didn't realize that's how the conversion kit was attached.
Getting the barrel done shouldn't be real hard but I'll have to see if I can find someone who can do a bolt for me. I wonder if it would be easier/cheaper to build an AR-10 bolt with a .223 bolt face or an AR-10 bcg that takes an AR-15 bolt? I imagine a similar type of magwell block to what is used to make a .223 lower work with 9mm mags would be relatively simple?
If you go with an ar15 bolt you would need a custom barrel extension to fit the bolt as a 308 one wouldnt work. I would think that a machine shop should be able to put a sleeve in a 308 bolt and have it work. That way there would be no changes in the metals integrity
Good point on the barrel extension. When you say " put a sleeve in a 308 bolt" do you mean sleeve the inside of the bolt face to bring it down to .223 size?
Yes. I was just thinking if you cut a groove in the bolt and had a corresponding ridge on the sleeve with a cut out for the ejector and extractor and put it in like a snap ring you would never have to worry about it coming out or rotating
Makes sense. I even found a guy to do it. Just need to figure out a mag well adapter now...
Ilove12gshotguns
CGN Regular
- Location
- New Brunswick
Something to think about, maybe bring your stag10 upper and have them machine you an adapter to fit an AR15 barrel?
