I am considering switching my grip core on my Magpul MIAD grip to the one that holds a spare bolt and firing pin. Currently, it holds spare AA batteries for my EOTech, but I am about to switch to the Magpul STR stock and I can store the batteries there instead. If I am going to have the bolt and firing pin, I’d like to also have a small amount of gun oil stored too. Does anyone know where I can get a bottle of gun oil small enough that it would fit in the core with the bolt and firing pin? If not, how about something small enough that it would fit in the battery tube of the STR stock. Either way, I would need it to be in a secure enough container that I wouldn’t have to worry about it leaking oil all over my hand or the batteries in the stock. Another solution would be if anyone knows where I can find a very small, securely closing container that would fit and I could just fill it with gun oil myself. Thanks in advance for the suggestions.
I took an empty small bottle of Systane eye drops and filled it with Weaponshield and put in in my grip. A rag is folded up small and keeps the bottle in place. I think the MOE and MIAD are comparable in storage capacity. There is no room for a spare bolt even without the rag. You’ll have to find something thinner than an eye drop bottle. Hope that’s some help.
Got a small dropper bottle to fit perfectly in a Tango Down stubby VGG.
SLIP 2000 has just what you need:
http://www.slip2000.com/mm5/merchant.mvc?Store_Code=S&Screen=PROD&Product_Code=60314
This small bottle is approximately:
2-5/16" H x .69" W
About the circumference as a 3.0V battery #123.
That is perfect! Do you know if the bottles are refillable?
Probably. I image you could refill with a needle oiler or simply suction more out of a larger vessel. I usually buy by the gallon and simply refill my 1 and 4 oz containers. Works for me.
Dont buy another core. If it doesnt fit in the AA batt core, use the one that came with the grip… Just take out the rubber insert. If your bottle doesnt fit snug, just stick rubber strips around the inside.
Not being a prick, just asking:
What’s the benefit of this over keeping a bottle in a pouch? Or in the patrol car if you’re a LEO?
LaRue throws in a small bottle of their machine gunners lube when you buy stuff from them. I’ve got these little bottles stashed somewhere on every rifle.
A re-tasked eye drop bottle filled with your lube of choice works well too. Stick it into a snack size Ziplok baggie and it will also help to keep the bottle from rattling around.
For those who are not LEO and may have to engage bad guys in just your underwear.
Since she likes to be kept wet (and can bitch if she is not), having some lube stored on the gun is IMO a good idea.
So does Sprinco when you order any buffer/extractor spring kit.
Okay, but if you’re in your underwear and are being assailed by baddies, and you’ve fired so many rounds that the lube on the BCG has gone . . . .
I mean, it’s a bit silly. Come on.
Keeping your HD carbine lubed in storage, and then cycling the action a few times every so often is fine. Anything more than that is a solution looking for a nonexistent problem.
I’m doing a visual on that scenario right now, and depending on who the shooter is, could be or not a pretty picture. 
Pardon my warped sense of humor…
I got a box of expired eyedrops from my eye doc. Pop off the dropper tip and replaced with oil. Marked all with oil from a paint pen. Oil sucks in your eyes.
I think its a .3ml bottle.
there’s nothing wrong with keeping larger supply bottles somewhere else. but this way, there’s always lube available where it’s supposed to be - with the gun…
Don’t need lube if I don’t have ammo. Therefore, keeping it near the ammo seems to work fine as well.
I’d counter by asking “what benefit is there to NOT keeping a small bottle stored on the rifle?”
Seems it would be cheap function insurance in the event you happened to be caught in need of some away from home, patrol unit or aforementioned pouch. 
Magpul makes inserts for ammo and a spare bolt, so stashing some oil in the grip does not seem entirely counter-intuitive.
Personally, I keep some suntan lotion in there…
Really rural LEO. I’m semi-regularly away from my rig for the better part of a shift and occasionally for days at a time. I usually grab the rifle and will almost always grab a patrol bandoleer and a pack; but if for some reason I was to grab the gun and run it would be nice to have some essentials on the weapon itself.
you lube your ammo?