Modular magwell project.

[theredneckengineer]

Its reversibility would be hindered by the required larger magazine opening, depending on what magazines are desired. If you are welding something on, then that's something additionally that would have to be reversed. I am curious about your idea, but I get that you might want to keep that to yourself. Plan on making one? I could see a tac welded rail, dovetail or lug of sorts being another method of attachment, but I don't think I prefer that.

I have no problem sharing ideas and concepts; perhaps someone else will take the idea and further develop it.
Like a number of other ideas and concepts I have, I'd love to make one but I just don't have the time right now.


There's two ideas I have considered, both would require removal of the existing magazine well and trigger guard. You'd have to weld the feed ramp portion of the trigger guard from the bottom (to keep your feed ramp), which isn't necessarily a bad thing.

Idea 1: Make an aluminum, polymer, or injection molded plastic outer sleeve that fits over the bottom half of the mac receiver and is retained by the front take down pin and a modified buttstock release assembly and release assembly pin. The plastic outer sleeve would have a dovetail on the bottom around the magwell area and on the front, under the take down pin. Each magazine conversion type would be a plastic/polymer/aluminum shell that slips over the dovetail on the aforementioned receiver sleeve. Spring loaded locating pins would keep it from moving fore/aft.
Downside is the amount and cost of polymer components that have to be fabricated and might look odd.
Upside is no welding is necessary.

Idea 2. Weld a bracket around the original magwell area that has dovetails in it and a lug in front, under the take down pin.
Each magwell would be machined aluminum or polymer and would slide over those same dovetails and the trigger guard of that same lower would be supported by the front lug.
The downside is that the receiver has to have the dovetails and front lug welded on, but it's no different than welding on a new magwell anyway. Upside being it would be much cheaper and faster compared to option one.

In both cases, you'd still have a separate "lower" for each desired magwell (which could then be "tuned" to that particular gun) and neither case would require drilling or cutting the registered receiver.

 

[bigj480]

It would basically attach similar to an uzi grip assm if it wasn't clear with my sketch.

Doesn't the Uzi grip assembly use a tab and pin? I'll look into it.

 

[bigj480]

Idea 1...

Idea 2...

My posts are too long, not going to quote in full. Idea 1 is interesting. It's basically a rail it dovetail like I mentioned in my other post but built into a poly reciever cover rather than welded on. To be honest, I tried no to do it the way I'm doing now because I wanted the smallest total package. I didn't want the adaptor any larger than the grip/tririer guard. That said, so much is gained from using the td pin that it's worth it. It's as small as it can be and still be convenient and easy. Smaller designs will require tools to attach or more reciever mods. I feel like the system you describe makes a lot of sense if it was part of the reciever. As a separate polymer part that still attaches at two points, I just don't think the pros (likely stiffer) outweigh the cons (larger, more complicated, maybe looks). I'll consider this some though, it has merit. One thing that is coming to mind the possibility of a polymer rail at the rear, without a reciever cover. Several ways it could be attached. I think it would still result in a large overall package but I have to think about it, might lead to something. Right now I plan on pretty much using the bottom of the reciever as sort of a rail in that it slots into the grip unit.

Idea 2 is less appealing to me, because it adds welding and will still end up larger/thicker. I understand that you are saying the feed ramp will have to be welded at the bottom of the of the reciever if the trigger guard is removed. One thing I don't get is that a front lug does that the takedown pin doesn't already do. The front of the gun is already a lug of sorts. I'll ponder these. I l

 

[bigj480]

So here is an issue I'm coming up against. What is the longest cartridge I should plan for? PDW calibers like 5.7 and 4.6 are pretty cool IMHO. I was surprised to see that 4.6 is cheaper than 5.7 right now. The thing is, they are long. I haven't measured but I don't think they can be run on an A1 sized gun. They will almost certainly be limited to M11/9s due to their length. That means a different magazine cut out would be needed for M11s to run these longer mags. I think it's worth it and any future rounds with the same general profile would be likely to work. Anyway, is that the longest I should go for? That seems to be the limit to me.

I'm ordering more filament today and what I want to do ASAP is get the demo receiver and Glock module prototype printed and post a video of it cycling manually. Hopefully by next weekend. I might then just go ahead with modding one of my guns to run it, just to make it real. I will probably start with my RPB and 9mm only CFW A bolt. I would like to do all of the receiver mods myself, using very basic tools, just to prove how easy it is. If we all agree that the feed ramp must be welded at the bottom, then I will have to get that done as I don't weld. I need to pick up an A1 sized side cocker from somewhere and throw my 9mm 3 lug barrel in it.

Just now getting around to checking takedown pin to feed ramp measurements (front of pin to rear of feed ramp). The result is 90.66mm for M11/9 and 87.43mm for RPB, the pin is 7.86 diameter. A little over 3mm difference is considerable... I BET that large magwell M11A1s are more in line with the M11/9 measurement. I bet you there is less variance when comparing two guns of the same model. I would appreciate any measurements you guys can offer, including pin diameter, as those can vary.

For those who don't know, that difference is a little over 1.5x time the thickness of the metal the receiver is made out of. It is possible that 3mm of EXTRA distance from mag to feed ramp would be fine or even beneficial for feeding. The face of the bolt already goes beyond the rear of the magazine when it cycles. The only way it would make a difference is if the bolt is already on the verge of short stroking. Most people don't own 2 M11s so rather than making a one size fits all part (what I might prefer for myself), I will optomise for each model. Not going to cut corners in the interest of a more universal part. That said, again, any measurements you guys could offer would be very much appreciated.

 

[theredneckengineer]

So here is an issue I'm coming up against. What is the longest cartridge I should plan for? PDW calibers like 5.7 and 4.6 are pretty cool IMHO. I was surprised to see that 4.6 is cheaper than 5.7 right now. The thing is, they are long. I haven't measured but I don't think they can be run on an A1 sized gun. They will almost certainly be limited to M11/9s due to their length.

Just my opinion, but I would not bother with modifying the magwell (or your modular magwell design) for the 4.6 or 5.7 length cartridges.
The 4.6 is a pretty hot little round (58 ksi) and really needs a locked-breech action like the MP7 as opposed to a blowback system. I don't see anyone bringing an upper to market for that round, but I suppose it could happen.

The 5.7 (also fairly hot at 50 ksi) would work with a blowback system with a heavy bolt, but there still aren't any uppers on the market.

Anything much longer than the 10mm cartridge just wouldn't make a lot of sense to modify the gun or grip system around IMO.

 

[bigj480]

My hope is that a locked breach upper comes along. I have a design in mind, but we'll see. That's an ambitious project. I may offer two versions of the grips, one capable of pdw rounds and one not...or just save that for the future. I don't know what you guys are down for. I would just rather have to only mod the receiver once and have a grip that would fill that cut out in the receiver. One thing at a time I guess, single feed pistol caliber uppers right now. Btw, the design has changed to use a part of the trigger guard as a lug and index off of that. This should make the design universal and smaller.

ETA: Finding a good solution that is toolless and can be installed without removing the upper is proving difficult...I almost want to go back to m-lok, at least for the rear. It would only require about 1/4" extra slot at the rear of the mag cut out. I do still have a few ideas and I can try them out on a mock receiver. How important is that to you guys?

 

[bigj480]

Off work because COVID 19 (a guy tested positive). At least I'm making some progress on this...and staying up too late. Going to improve some things from here. It feeds great when manually cycling. As it stands it takes G17 mags but the actual grip length is G19-ish (or slightly shorter?). I think the grip is too short, but if I make it flush fit 21 rounders (about G17 grip length) then I don't think 50 round drums will work. I have some 50rd drums and I'll check. There are cheap 40 round mags though. Beta drum will still work either way but its snug against the hand. What do you guys prefer? Grip needs texture or grip tape of course, but it feels nice as-is.

PS: If any of you guys have a 21 round Glock 9mm magazine and you can give me a measurement, let me know.

 

[Gaujo]

Is this full custom, not another frame converted?

I would design it to work with glock oem mags, 17, 18 so the 17 round and 33rd 9mm. I am not familiar with the 21 or 40 rounders, the cheap ones I have seen are the KCI 33 round Korean mags.

As to grip size I prefer g17 over g19. I think the same preference seems to be expressed by the marketplace when you look at the kel-tec sub 2000. I don't have access to production numbers or anythign but they make it in both grip sizes and the g17 seems to be more popular and resell for more.

 

[A&S Conversions]

To me the Glock magwell needs a custom grip/magwell. The centerline of the Glock bore is lower than the M11. So using a Glock grip/magwell on the M11 puts the grip down so low that where you would normally hold the grip is off. As shown in the picture above, where a Glock grip/magwell would normally be held isn't all there. To me, a custom grip/magwell with a catch placing the mag at the height it is needed for M11 use and still have a complete grip.

Scott

ETA: I think that this is a good first effort. Good for you to build a proof of concept. But I would think that the grip/magwell needs to have a full size grip.

 

[bigj480]

Is this full custom, not another frame converted?

It is a stand-in for my RR until I nail down the design of the grip and how it attaches.

I would design it to work with Glock OEM mags...As to grip size I prefer g17 over g19.

Yeah, it will of course work with factory Glock mags, it's just a question of the lowest capacity mag that will fit. A grip that is comparable to a G17 in length will need a longer mag than a 17 rounder. People rarely run their guns with flush round mags now, so it almost don't matter. If I do want flush mags, I'll just run the Magpul 21 rounders. Easy. I actually like that 21 rounders will be flush.

To me the Glock magwell needs a custom grip/magwell.

Yeah, I'm trying to be short with my posts because walls of text are offputting, so I didn't list everything I was going to change. There are a number of things I'm changing. The outside surface of the grip will basically be moved down, providing for more normal grip. It was actually comfortable but not ideal. Mag release location is not an issue, even though it's higher than it is on a Glock. I prefer to keep parts commonality with Glock and it does work perfectly fine, but I'll look into a redesigned mag release.

ETA: I think that this is a good first effort. Good for you to build a proof of concept. But I would think that the grip/magwell needs to have a full size grip.

Thanks Scott! Yeah, it was pretty much a proof of concept at this stage, to make sure feeding was right. I'm adding more material above the TG, lengthening the grip and rounding the trigger guard. Oh, and removing the mag stop, it's not needed. I've decided that toolless attachment is not a smart move as well. It has a bolt at the rear of the grip. Nothing is more important that solid mounting and having to use a screwdriver to change grips is no biggie. Sliding into tabs made out of the removed trigger guard is surprisingly solid and snug.

 

[strobro32]

Moving forward! Good job.

The short "G19" grip that can only use G17 or longer mags was the challenge I ran into. I found the G grip that I played around with for the M11 is shorter than the G19.

 

[Jmacken37]

Nicely done BigJ480! I love this!

 

[bigj480]

Thanks guys. Below is a rough mock-up and pretty much everything is changing other than the general attachment method, so ignore everything else. The current attachment method works, but I don't care for steel on plastic when there is a small surface area like at the lugs. This new method will use steel pins located in a way that it pushes the grip firmly against the receiver bottom.

In this pic, the blue part is 3d printed and contains a threaded insert. I'm looking to replace that with a large metal nut of some sort, something stocked my McMaster-Carr probably, and with the right thread pitch of course. No luck finding anything perfect yet, probably will end up being a modified T-slot nut. You can also get an idea of the new magwell opening size and shape. That mag stop is going away.

Pic of the bolt at the rear.

 

[Schwartzer]

I worked on this idea a while ago. My design kept the trigger guard and put a dove tail on it. I increased the block that holds the stock added a dove tail and a way to lock the magwell in place. Slide one off slide another on another tighten one locking screw. It also could be possible to bolt onto the stock block instead of replacing it. I do like the idea of the magwell and trigger guard. One question is how will you deal with the feed ramp?

https://flic.kr/p/ZsLDeL
https://flic.kr/p/ZsLBRf
https://flic.kr/p/YvPoug

 

[bigj480]

Pretty cool, thanks for sharing your idea. There are many ways to do this, that's why I asked for input. The feed ramp would be welded to the receiver in additional places to make it as secure as possible. If your question is actually about the necessity of a different feed ramp for double feed mags, it would just have to use a drop-in feed ramp like the one Lage offered. I have let this project set on the back burner for a bit, but I do have a mag well that will now work with G17 mags while maintaining a full-length grip. At this stage, the next move is either having a shop cut the lower or devising a way to consistently do it myself. I have some ideas regarding this.

 

[Jmacken37]

At this stage, the next move is either having a shop cut the lower or devising a way to consistently do it myself. I have some ideas regarding this.

Cajones!

 

[Schwartzer]

At this stage, the next move is either having a shop cut the lower or devising a way to consistently do it myself. I have some ideas regarding this.

Dremel and hack saw. Slow and easy tape everything else for oops. If you are welding in a feed ramp why not in one that takes single and double feed?
I thought lage did a drop in double feed so you would not require to weld on the lower. Cant wait to see how it goes for you. Where did you get the mag well?

 

[bigj480]

Cajones!

Yeah, it feels sketchy to me too but once I make the jump it will be fine. I really need a lower other than my RR to do first. Maybe I should buy a semi.

Dremel and hack saw. Slow and easy tape everything else for oops. If you are welding in a feed ramp why not in one that takes single and double feed?
I thought lage did a drop in double-feed so you would not require to weld on the lower. Cant wait to see how it goes for you. Where did you get the mag well?

I'm thinking of 3d printing jigs that attach to both the receiver and the Dremel that would give easily reproducible results and make it impossible to screw up. The issue with the feed ramp is that I need the rear of the trigger guard for my attachment method and I think equal results can be achieved without its removal. To be honest, I'm thinking that further welds are not needed, but it is an option. I would test without the welds first. I know this is a considerable mod but I'm trying to keep it to a minimum. No welding would be nice if it's something I want people to be able to do themselves, even if only a couple of people do. You are correct that IF welding has to be done it might as well be a double-feed ramp of some sort. I 3d printed the mag well.