ARP9 / SSR9 至 M4 弹匣适配器

Here I've designed an adapter from a Standard ARP or SSR 9 mag to an M4 magazine.

I'm using it in my SSR4 DSG and designed it in a way that it fits a tiny bit tighter than the original mags, and therefore doesn't wobble as much.

It works with all M4 mags that I own, no matter if polymer or steel.
The BB's feed perfectly fine, even when using full auto (your M4 mag's spring needs to be strong enough, otherwise it could struggle a little with full auto - semi will be fine).

For the M4 Mag release I opted to use a standard M4 one, that can be inserted into the adapter just as it sits in your M4's lower receiver. (They can be bought online for as cheap as 5 bucks)
Therefore you don't have to do any complicated 3d print assembly and struggle with print tolerances ect. plus you can reach it with your right index finger just as if it were regularly on you weapon.

The adapter is printed best standing up and using manual tree supports on all overhangs except in the mag release hole.
I've used 9 Wall loops, 25 Top shell layers (at 0.16mm layer height for the little nub on the top to be solid) and 18% of honeycomb infill to make sure that it can withstand a beating.
As a filament I used PETG, which works fine.

Edit: I've added the notch at the top of the arp9 mag part. I'll include both versions (with and without).

9 wall loops, 0.16mm layer height, 18% honeycomb infill, PETG