3D Print Your Own 6.5 Grendel (or other odd caliber) AK Magazines
Click here to download the Fusion 3D files discussed in this article
Update 20JUL2026: further tweaks to reinforce weak areas
Update 23NOV2025: reinforced the back of the magazine near the locking lug. Reduced thickness at the very top of the feed lips to bring rounds 0.6mm higher into the feed well to reduce contact with the bullet guide.
This is a fully parametric (in theory–it’s a bit of a spaghetti mess in some places) AK-style magazine design which I designed to accommodate 25 6.5 Grendel cartridges.
By adjusting model parameters, you can adapt it to many other cartridges, to include perfectly straight walled cartridges like .350 legend or even heavily tapered 7.62x39. If this model gets any traffic, I will update the files with additional, ready-made versions for other common cartridges. Not sure how much curvature you need? Reference the table of banana factor below:
Banana Factor
Banana factor is the amount of curve introduced by stacking the cartridges together. It is influenced by the difference in diameter between the largest and smallest point of cases which touch as they stack together. More taper = more banana. Choosing extra banana lets you avoid having to make the follower tilt to account for an ever-increasing angle as cartridges are stacked together. Remember that they stack in rows of two, so the geometry problem is a little more complex than just a simple single stack (though estimation of banana factor by looking at the single stack usually is sufficient). Look what would happens if you tried to stack 7.62x39 cartridges in a magazine without a banana!
| Cartridge | Large Dim (mm) | Small Dim (mm) | Distance (mm) | Circumference (Banana Factor) | Deflection (deg) |
|---|---|---|---|---|---|
| 30 Thompson Center | 11.946 | 11.806 | 29.21 | 7738.55 | 6.978 |
| 22 Creedmoor | 11.946 | 11.758 | 29.21 | 5739.35 | 9.409 |
| 6 mm Creedmoor | 11.946 | 11.758 | 29.21 | 5739.35 | 9.409 |
| 277 Fury | 11.946 | 11.724 | 31.75 | 5267.73 | 10.251 |
| 6.5 Creedmoor | 12.010 | 11.740 | 36.47 | 4981.93 | 10.839 |
| 30 Nosler | 13.970 | 13.462 | 44.45 | 3700.72 | 14.592 |
| 223 Ackley Improved | 9.652 | 9.327 | 37.72 | 3399.49 | 15.885 |
| 6.5 Grendel | 11.200 | 10.968 | 20.32 | 3018.09 | 17.892 |
| 6 mm ARC | 11.201 | 10.960 | 20.32 | 2903.27 | 18.600 |
| 17 Remington Fireball | 9.548 | 9.304 | 20.32 | 2434.3 | 22.183 |
| 204 Ruger | 9.548 | 9.182 | 30.48 | 2402.38 | 22.478 |
| 222 Remington Magnum | 9.535 | 9.093 | 30.48 | 1970.06 | 27.410 |
| 224 Valkyrie | 10.686 | 10.330 | 20.23 | 1844.34 | 29.279 |
| 300 ACC Blackout | 9.548 | 9.192 | 20.32 | 1648.46 | 32.758 |
| .223 Remington | 9.548 | 9.103 | 25.48 | 1637.64 | 32.974 |
| 17 Remington | 9.548 | 9.103 | 25.48 | 1637.64 | 32.974 |
credit to a discord member Warmbo for putting this together
Design Parameters
The following parameters can be tweaked (please let me know if you have any issues–I work chaotically and some relationships might not have made it into this version), including cartridge OAL, magazine width at front and back, case shoulder location, angle of “bumpers” that bump the cartridge into the center, feed lip thickness, height, and reinforcement amount, locking lug placement and size, and, finally, magazine length and curvature.
To modify the curvature of the magazine, alter the Banana Factor in parameters. As follower and mag curvature are based on a percentage of a sweep, you will have to figure out the new percentage of sweep to correspond with your updated banana factor. For example, for 6.5 Grendel, the Banana Factor is 1509mm (radius) and the length coefficient is 0.00010333, whereas for 6.5 Creedmoor, the Banana Factor is 2490mm and the length coefficient is 0.0000646. You will need to determine the correct length coefficient for your magazine; the best way to do this is to simply input your desired Banana Factor, measure the length of the resultant magazine created by the Magazine Length parameter (desired length in mm*lengthcoefficient), determine the percentage that this value differs from your desired length and multiply your length coefficient by the difference.
For this 164mm 6.5 , you must obtain a 30-round PMAG spring and a WBP or Arsenal stamped steel 7.62x39mm magazine floor plate. These are easily obtained.
Print Consideration
These magazines perform well when printed in fiber-reinforced nylon and are far better than the only option on the market for 6.5G AK magazines, which have poorly tuned springs and tend to severely dent cartridges on feeding. They still have weak feed lips due to poor layer adhesion–I’m working on ways to anneal the print to achieve better interlocking between layers. Maybe someone better at 3d printing will be able to solve this issue where I failed.
Filament requirements:
Body: Must be a PA-CF (highest interlayer strength, beats PAHT-CF) Lug: PA-CF Follower/floor plate: ASA/ABS (or more PA if you really want to) 6 wall loops/80% infill
Magazine should be printed at around a 30 degree angle from vertical on the print bed leaning backward. The locking lug should be printed laying on its side to maximize strength on the axes exercise as It is inserted and removed. I have not yet determined an optimal print orientation for the follower and floor plate, but these items experience minimal forces and can be printed out of PETG/ABS/ASA without issue. I welcome your feedback as far as determining the best way to print these internal parts.
