Acme Firearms : Precision Quality Accuracy

Ideal Small Arms - '20-Plus'

Acme Firearms LogoAustralian Made Small ArmsAustralian designed modular magazine attachment

Ideal Small Arms - '20-Plus' snap-locks onto magazine base to create increased magazine length and capacity

At Acme Firearms, in our Langwarrin workshop we've designed a stackable '20-Plus' modular magazine attachment which snap-locks onto the base of a magazine. '20-Plus' can hold up to twenty 5.56NATO/223REM/300BLK cartridges. Stack additional '20-Plus' to create larger magazine capacities.

Ideal Small Arms '20-Plus' align=



In March 2018, after three years of development, Acme Firearms completed inhouse design and manufacture of our '20-Plus' device.

'20-Plus' is a modular magazine attachment designed to snap lock onto the base of our Ideal Small Arms 5.56NATO magazine (currently in pre-production) and can also be fitted onto Magpul Gen3 Pmag 5.56NATO magazines.

'20-Plus' increases magazine grip surface area, aiding positive insertion of magazine into firearm.

'20-Plus' capacity holds up to twenty cartridges.

Constructed from tough PA6 (Nylon) polymer plastic, weighing only 50 grams.



Slides and snap-locks onto a magazine within seconds.

Video shows '20-Plus' being fitted onto a Magpul Gen3 Pmag magazine. '20-Plus' is injection moulded from tough PA6 (Nylon) polymer plastic. UV resistant, gun oil and lubricant resistant.

'20-Plus' slides and snap-locks onto the base of Magpul Gen3 Pmag - 5.56NATO/223REM/300BLK magazines. Swap out Magpul main spring with longer Ideal Small Arms spring.

Please note:- '20-Plus' fits Magpul Gen3 Pmag - 5.56NATO/223REM/300BLK magazines. Shall not fit earlier generation Pmags. To purchase Magpul Gen3 Pmags, click here

Send us an email to order. Please advise product code, quantity required, your name, delivery address. We'll send you a no obligation quotation with payment options. We ship '20-Plus' to Australian destinations by Australia Post from $9.90

Please check with your relevant state law enforcement authority to verify you may legally possess these articles in your particular state. Prices are cash with effect from 13 March 2018, and subject to change without notice.


Genesis and Development of '20-Plus'

We started to experiment with magazines in 2015. Over a two year period, we designed and created a number of different capacity prototype magazines.


We 3D-printed prototype plastic magazines and also machined many from aluminium with our CNC Vertical milling machine. We experimented with 5, 10, 15 and 20 capacity magazines which all turned out 'awesome' and amongst our best work!

The final step was to build plastic injection moulds for all our magazines.

We examined the manufacturing costs of plastic injection moulds for our magazines. We had too many magazine moulds. The steel moulds and cores were large in size and building so many of them, correspondingly expensive. The whole project became unaffordable based on return on investment. We had to cancel this approach ... "If only, there was a better way!".

Our breakthrough moment!

Australian Ideal Small Arms '20-Plus' attached to AR15 magazineOur breakthrough moment happened with the design of a '5-Plus' device, (We initially created a '5-Plus', then '10-Plus' and finally settled on '20-Plus'). The invention is a stackable magazine device which snap-locks onto the base of a magazine. Enabling stacking of additional '20-Plus' to create large magazine capacities. Our new approach resulted in an overall reduction in plastic injection mould size when compared to traditional high capacity magazine moulds. Manufacturing costs fell dramatically. Finally, a commercially viable solution!

Best of all, there is nothing like our '20-Plus' magazine system available for sale anywhere in the world!

We export internationally.

Australian and international firearm owners can now quickly create their own magazines with our '20-Plus'.

No Screws Required

Assembly is done without any screws. Modular design ensures perfect fit.

In-Field Adaptability

  1. Magazine capacity can be adapted for changing circumstances.
  2. Determine your own magazine capacity or grip length; short for benchrest or extended length for easier handling.
  3. When shooting from a helicopter and flying time costs money, adapt for largest capacity.
  4. Stay on target longer, without having to change magazines as often.


Magpul Gen3 Pmag compatibility

Compatible with Magpul Gen3 Pmag - 5.56NATO/223REM/300BLK magazines. ‘20-Plus’ won’t connect to earlier generation Pmags.

Attach Magpul Gen3 Pmag by snap-locking '20-Plus' to base. Some light filing is required to knock off plastic edges on Pmag, takes about one minute to sort out. When Pmag mating edges are chamfered, the follower can travel smoothly without potentially becoming stuck. We recommend gluing Pmag to maintain alignment. View instruction video here.

There shall be no alignment issues with our matching Ideal Small Arms 5.56NATO magazine, currently in pre-production. Our matching ISA magazine shall be available in 9 months.

Key features of '20-Plus'

  1. Design and manufactured in Australia.
  2. '20-Plus' is designed for calibres 5.56NATO, 223REM & 300BLK.
  3. Modular design, allows stacking of additional '20-Plus'.
  4. Manufactured for attachment onto our Ideal Small Arms 5.56NATO magazine (currrently in pre-production).
  5. Compatible with Magpul Gen3 Pmag - 5.56NATO/223REM/300BLK magazines. (Some filing may be required to knock off plastic edges on Pmag, takes about one minute to sort out).
  6. '20-Plus' constructed from tough PA6 (Nylon) polymer plastic.
  7. UV resistant, gun oil and lubricant resistant.
  8. Light weight at only 50 grams.
  9. Longer main springs available for capacities of up to 30 and more cartridges.
  10. Slides and snap-locks onto magazine base.
  11. Audible 'click' when '20-Plus' locks into place.
  12. Constant internal curve geometry, for improved feeding.
  13. No fastners or screws required for assembly.
  14. Design feature enabling permanent gluing of assembly to prevent disassembly.
  15. Magazine capacity is only limited by length of main spring. We've experimented with huge capacities. Huge magazines become very heavy and impractical in the field, but alot of fun at the shooting range.

Comments from Klaus, creator of Ideal Small Arms '20-Plus'

"This is a device created for people to assemble in their home workshops or out in the field. We also offer preassembled units to get people going immediately."

"During the design and manufacturing process, the original '5-Plus' prototype morphed into our '20-Plus'."

"An interesting revelation throughout testing, was observing human interaction with our prototypes; people generally would stack multiple '5-Plus' to create a '20-Plus'."

"Our main market is overseas, where '20-Plus' makes more commercial sense for our Australian business."

"Our '20-Plus' is designed to attach and perfectly align with our ISA magazine. We're currently finalising pre-production on our Ideal Small Arms 10 cartridge magazine, due for release in about 9 months. We've decided to release our '20-Plus' ahead of schedule because they can also be connected to Magpul Gen3 Pmags."

"Our most frequently asked question is does our '20-Plus' fit other magazines? They can be attached to Magpul Gen3 Pmag 5.56NATO magazines and with a little hand filing, satisfactorily do the job. It takes about one minute to modify a Pmag to fit. Please view instructions to see what's involved."

"Another frequent question; are there any other calibres on offer? ... Not at this time ... I need to focus all my attention to completing our matching ISA 5.56NATO magazine and I also have another two inventions on the go at the moment. Perhaps in about 2 years I'll look at other calibres. After all, I'm just a man in a workshop juggling a number of projects, all at the same time."

"I find the most difficult aspect of inventing, is following through to completion and getting my invention to market. It's always more appealing to go to my CAD software and start a new project ... it's a struggle!"

Klaus von zum Hof,

Proprietor Acme Firearms, creator of Ideal Small Arms '20-Plus'

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