It only seems to occur with First aid kits. Locksmith, repair, medkits, and canteens don't have the problem at all.

Sometimes when I combine i get one of those odd pop ups that says You cant merge first aid kit with first aid

well after a total save crash which hit both my autosave and my backup died and i had to start all over I havnt had the crash yet. It may have simply been some small error in the location of files or something.

I know that two magazines of the same ammunition can be used in a gun but it would be kinda cool if we could make better use of different sized magazines for wieght purposes. Like 15 shot desingated marksmen magazines for M16 family of rifles.

Now I use the word "exploiting," as this is not part of Warmsteel's plan, purely an unintentional consequence, and the underlining mechanism may be dropped along the path through Beta and into main 1.13.

Once NAS is part of the main 1.13, I hope to be exploiting a certain property of WarmSteel's work to produce a pseudo-magazine well system.

Still, I am hoping (as Warmsteel commented) to separate caliber from weapon ID by turning magazines into attachments and using a dedicated ammo slot for weapons.

• The weapon has a "MagazineWellType" tag that references a list of magazine well types.
• Each magazine well type is defined as taking one caliber and a list of possible sizes (20rd, 30rd, etc., or possibly just a minimum and maximum size).
• Ammo items have a tag called "CanEmpty" or somesuch. If set to 1, the ammo item is a clip, and can become empty during gunfire. Otherwise it is loose ammo, and will disappear once depleted.
• Ammo then attaches to a special attachment slots that's completely reserved for it. It can only be attached if it has the same caliber and a suitable size for the Magazine Well Type involved.
• When weapons are fired, they can empty a magazine if it has the CanEmpty flag. In such a case you're left with an ammo item with no bullets in it. You can refill this item using any other ammo item that shares the same caliber and ammo type (unfortunately, loading several different bullet types into a single magazine is much more complex to do).
• If you want attachments like a Mag Adapter, those attachments will simply change the weapon's Magazine Well Type to another type, and then it can different sizes of magazines based on the new Well Type.

In addition, if attachments on attachments become possible (or are they?), you could do things like magazines taped together, in which case when one is emptied the automatic reload will simply switch the two around. Other possibilities will also open up once this feature is enabled.

Just to clarify, what I'm proposing is:

• The weapon has a "MagazineWellType" tag that references a list of magazine well types.
• Each magazine well type is defined as taking one caliber and a list of possible sizes (20rd, 30rd, etc., or possibly just a minimum and maximum size).
  ...

• FN Mk.16 accepts all M16-type magazines. But with EGLM attached it cannot accept drum and double-drum magazines.
• FN Minimi/SAW accepts belt and M16 30 rd magazine. It cannot accept C-Mag 100-rounder with M-16 feed clip, but can accept C-Mag with SAW feed clip. M16 can accept both C-Mag M16 and SAW feed clips. Also, feeding Minimi with magazines gives it +200 rpm to technical rate of fire.
• Glock 19 accepts 15 rd and 17 rd magazines, 17 rd magazine can be 15-rounder with +2 magazine extender. 17th model cant accept last one, however it accepts normal 17-rounder.
• Chinese Type 63/68 accepts proprietary 20 and 30 rd magazines. It also accepts all types of 7.62 AK magazines, but in that case it loses bolt catch feature. And like many older battle rifles (SVT, Gew.43, MAS-49) it can be filled from clip when empty magazine is attached.
• Inch FALs can accept their own magazines, metric FAL magazines, Bren L4 30 rd magazines. But metric FALs can accept only metric FAL magazines.
• .357 revolvers and spidloaders can use .38 ammo.
  etc, etc

Here is the list of weapons which have burst or auto fire but do not allow for a rod & spring attachments in SVN 1203 build 3287:

Ruger Mini-14

Auto Rocket Rifle

Calico M-950

SR-2 Veresk

Metal Storm Surf Zone

ColtCanada C7CT

AKMSU

Steyr ACR

Owen .45
MAT-49
SIG MP41/44
AR57 16"
AR57 11"
AR57 6"-Silenced