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Opportunity if anyone plays with 3D printers


GarrettJ
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So I was just looking over Gunbroker at asking and completed prices for Reising mags. They have always been kind of spendy, just due to the relatively low numbers out there. Now they are going for anywhere from $100-$300 when people can find them.

So I pulled out an Uzi .45 magazine, just to see. The Uzi mag is noticeably thinner than the Reising mag, as well as being more narrow front-to-back. It looks like there may be enough room to fit a magwell adapter in there. It could latch in place using the standard Reising mag catch, and then have another catch in the standard Uzi location.

While Uzi .45 mags are also not inexpensive, I have found the Promag 22-round mags seem to work fairly well. Just holding it and cycling the bolt by hand it looks like it could work.

I'm not sure if an in-place adapter would be thick enough to withstand inserting/removing the Uzi mags into a long adapter. But what about making an adapter sleeve that stays attached to the mag? The Uzi mag would provide structural stability to the adapter at that point. I wonder if the plastic would hold up at the mag catch. Maybe a piece of sheet metal with a hole could be incorporated / molded into the plastic 3D print.

Promags can be had for around $30. Add maybe $20-25 for the mag adapter sleeve, and it could be something. If someone wants to run with it and see if they can get it to work.


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Edited by GarrettJ
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That looks interesting, and I'd be willing to take a stab at it. I think a permanent adapter would be the way to go, then there would be no need to create the UZI mag catch. But I would need to borrow one (or more) Promags and the Reising mag housing. There are two different mag housings, 12 round and 20 round, is that correct? It's been a couple of decades since I got to play with a Reising.

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You'd want a 20 round housing. The 12 round versions are grooved to match the 12 round mags and would be extremely unlikely to match the grooves in the Pro-Mag.

The good news is that Keystone sells repop 20 round housings so you wouldn't have to cut up an original

https://keystonearms.com/product/reising-maganzine-guide-20-or-30-round-stripped-repro/

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What I'm thinking is a (fairly) simple sleeve that would fit tightly on the Promag magazine, maybe removable, maybe permanent. It would then slide into the 20 round housing and lock with the original mag catch, no modifications to any original parts.

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Doug,

Drop me your mailing address and I'll send you a couple of the ProMags and a Reising mag housing for the 20rd mags. This is too good a chance to pass up with Reising mags selling for over $200 each!

Thanks,

Andrew

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Andrew, I'll also need to borrow an original 20 round mag so I can get the height correct. Does the mag housing have the mag catch? Won't be able to cost it out until I have it designed, but I'll be shocked if they cost over a buck. (Postage extra 😂) Edited by DougStump
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The photos of the Promag show two witness holes on both sides. If I put corresponding pins inside the sleeve to match, I wonder if they will provide sufficient retention. The pins can't be very long, can't have them interfere with the follower. I love a challenge!
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Great idea. An insert sounds great but I personally think a new mag housing would be a more ideal long-term solution. It could be purpose-built to include mag catch and release components at the appropriate heights/angles for the desired mag. The end product should lead to the greatest level of simplicity and reliability.

 

Edit: I was thinking of an insert to the mag well instead of a sleeve. Thanks.

Edited by heavy artillery
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That would be the preferred solution, except for one aspect. Money. It would cost a fair bit to set up the tooling to produce the new housing with a completely different UZI type mag catch. The housing would also extend down more so the catch would line up with the mag. How many Reising owners would buy one? This is where additive matching (3d printing) shines. If I can pull it off, what I envision is a sleeve that fits on the Promag with the notch on the back for the original mag catch. No modification to the Reising or changing parts, just pop in either an original 20 round mag or a sleeved Promag. If I can make the sleeve hold on to the Promag without being permanent, great. If not, we may have to epoxy the Promag in the sleeve. Cost to produce each sleeve will probably be a buck or less (postage will cost far more) and they can be printed as they are ordered so no inventory. And you get a choice of colors!😂
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Or you can just call Keystone and beg them to make more, or offer to buy the tooling that's already done?

If I were printing it might as well be in steel, not plastic, JMHO?

 

Just saw some sell at auction for under 100, even though I'd never pay that much, seem to be no shortage from what I've seen?

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The problem with the Keystones is that they don't function 100% and no one has figured out why. They appear to be identical to the Christies (the gold standard of Reising mags) and sometimes a given Keystone will run like a sewing machine and other times it will sputter and puke on the very same ammo. I'd say that what the world needs is a feed lip tool except that the lips on my H&R mags are dimensionally all over the place and run almost as reliably as the Chrisites despite their advanced age.

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...what I envision is a sleeve that fits on the Promag with the notch on the back for the original mag catch. No modification to the Reising or changing parts, just pop in either an original 20 round mag or a sleeved Promag.

That's exactly what I had in mind. Or it looks like for those who only have a Reising, it would be easiest to just make permanent mods to the Uzi mags.

 

So I was playing around this morning and tried cobbling something together just for a proof-of-concept. I think we're on to something here. I just used a wood spacer in the back with a hole drilled for the catch, and then used some cardboard to increase the mag width (the Reising mag is approximately .150" wider than the Uzi mag). I then went really high-tech and wrapped it all together using packing tape.

 

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Video link below. I ran the mag four times. The one malfunction in the first run was the only failure I had.

 

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And once we get this one figured out...

 

While a relatively inexpensive 22-round mag is good, it's still relatively low-capacity for a subgun. You really want at least 30-round mags for a subgun match, for example.

 

I've got an extended Uzi basepad from Taylor Freelance which gives an extra 10 rounds in a 9mm mag. Slapping that on the single-stack .45 mag I was able to get up to 25 rounds. I'll have to try to get out again and see if it will run. Now we just need to convince TF to make his Goliath basepad for the Uzi and see what we can get up to.

 

Here's the 25-round Uzi mag next to a 30-round Christie mag for comparison.

 

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I think our chances of success just went up, although I'm married & not allowed to think. With two pieces of card stock on both sides, how much play do you have side to side? I'm guessing the card stock is around .020" thick? So that is .040" on each side. I will have to have the front of the sleeve about as thick as the sides. Moving the Promag back .040" shouldn't cause problems???? I think the sleeve would be much stronger if it was a full "O" cross section instead of a "C".

 

I wonder how uniform are the different 20 round mag housings out there. We don't want the fit either too sloppy or too tight. What about making the sleeve OD slightly small on purpose, then have ribs (one or two in the front and two on each side) deliberately oversize that could be user sanded down for a perfect fit? Sanding a couple of ribs would be a lot easier than sanding the whole side of the sleeve.

 

Packing tape? How dare you! Duct tape or go home!

 

Unfortunately, I got interested in 3d printing after my Dad passed away. He would have gone nuts over the technology, things that would normally be time consuming or impossible to create are now simple. One example I use is: "Your assignment is to make a one inch perfectly square cube. It must be made in one piece, no seams or joints are permitted. Inside the cube must be a 1/2" spherical cavity. No holes can be cut into the cube." Impossible with conventional machining, but I've done it with 3d printing.

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I think our chances of success just went up, although I'm married & not allowed to think. With two pieces of card stock on both sides, how much play do you have side to side? I'm guessing the card stock is around .020" thick? So that is .040" on each side. I will have to have the front of the sleeve about as thick as the sides. Moving the Promag back .040" shouldn't cause problems???? I think the sleeve would be much stronger if it was a full "O" cross section instead of a "C".

 

It's actually pretty tight the way I have it. I did 2-ply card stock on one side and 4-ply on the other. (one piece folded over and 2 pieces each folded over). 2-ply is .052" thick. So rough numbers, .150" plus maybe another .015" for the tape, giving around .165" additional width to the mag, or roughly .083" added width per side.

 

For a sanity check, my Uzi mag measures anywhere from .816" to .822" where it would go up into the Reising magwell. An original H&R 20-round mag measures anywhere from .955" to .979" in the magwell area. My magwell width varies from .100" to .110".

 

I only have the one magwell to measure. And I've only taken measurements from one H&R mag and one Uzi mag. I have more of both types of mags if we need to validate measurements.

 

With the sides being only .083" thick, do you think you can find a material that is strong enough for this application?

 

I'm imagining a flexible tab at the bottom of the sleeve that would extend down and engage the Uzi mag notch. This would be below the Reising magwell, so could be made thicker to make it more durable.

 

The back of the sleeve would be quite a bit more thick. The wood block I used is .330" thick. I suspect the Reising mag catch would wear the catch in the plastic pretty quickly though, resulting in the mag sitting too low. Would it be possible to incorporate a metal plate with a hole for the mag catch? I'm thinking the sleeve could it could be printed onto/around it. Maybe the same for where the sleeve engages the Uzi mag catch.

 

I like your thought about adding ribs to custom fit the sleeve to the individual gun. I suspect we could actually have a fair amount of slop without causing reliability issues. But I agree it would be easier to start tight and sand to fit.

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Of course, for someone who has a Reising and doesn't have a .45 Uzi, it may be more expedient to just weld some spacers and rear block in place. I had originally bought the Uzi mags to use with a .40 conversion (they don't work, the cartridge stackup causes problems). I later found a grease gun Uzi grip so I'm set for either .40 or .45 using GG mags.

 

But this has me thinking maybe I should pick up a few more of the Promags while they're still readily available. I'm sure I could borrow a welder and tack something together.

 

But I still like the idea of the 3D printed sleeve.

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  • 2 weeks later...

Thats excellent! Any chance you can post a picture?

 

Let me know if you want some beta testing with another gun & mags. I have 6 or 7 of the promags, plus a handful of IMI mags, which would be interesting to try as well.

 

Did you just use the plastic material at the mag catch? Does it look like its going to hold up under repeated use, or do you think it will need to be reinforced?

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post-206-0-29149600-1599397873_thumb.jpgpost-206-0-06416200-1599397991_thumb.jpgpost-206-0-42414200-1599398106_thumb.jpg

 

As these were just a test, I used the color filament that was in the printer. Production sleeves will by black. I made a generous bevel on the top so it slides easily under the magazine catch, they go in much easier than an original mag. Reinforcing the mag catch hole with metal would be pretty difficult. We'll have to see how they hold up, but when they wear out just replace the sleeve.

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PM sent.

 

I measured 6 of the Promags plus the three IMI Uzi mags that I own. I just hit several points along the upper couple inches of the mag and recorded the high and low reading for each mag. So the measurements below show a range for each mag. I measured width and front-to-back.

 

Promag

.803-.805 x 1.334-1.340

.810-.815 x 1.335-1.340

.824-.832 x 1.335-1.341

.805-.815 x 1.330-1.338

.802-.819 x 1.331-1.339

.800-.814 x 1.340-1.345

 

IMI

.831-.843 x 1.325-1.328

.825-.832 x 1.325-1.327

.825-.829 x 1.326-1.328

 

So we will have to see if the sleeve will slide onto the IMI mags. If you think it would help, I can send you one of the IMI mags to model a sleeve on. And then you could see if that would still work on the Promags.

Edited by GarrettJ
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Ok - so I got some of the prototype mag sleeves from DougStump to try out today. The first mag ran flawlessly. After that, not as much.

 

However, it seems I had to tweak all of my Reising mags initially in order to get them to run. This was true for both H&R and aftermarket mags. So I adjusted the Uzi mags out a little and tried again. I found the feed lips need to be at least .450" apart at the front, and .460" might be better. Some mags were a little narrow as received.

 

After that they ran great. I'm going to have to try some more, but so far it's looking really good!

 

Also, the plastic used for the sleeve seems fairly durable. I was worried about wearing out the mag catch hole after repeated insertions/removals. I'll have to try shoving one of the mags in and out several times, but so far it seems just barely scuffed. Again, I think we may have something here.

 

Video below. Skip to about the 3-minute mark to see the mags running. Before that shows some of the failures prior to adjusting the feed lips.

 

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