You'll have to have at least one ticket to either the Fund or the Chamber to pull that off. It will be a great option for those who weren't sold on buying them both in the beginning but suddenly changed their mind already inside the Kremlin.
Yes, you can buy tickets to both the Fund and the Armory right from within the Armory building because both museums are in the same building. Here's the scheme of what's inside the Armory building. It's not the most mathematically (or geometrically) correct one, but it works:
See? Despite the fact that there are two separate lines and two entrances to the Fund and the Chamber outside of the building, eventually it's all interconnected inside and leads almost to the same place.
So how to buy them?
First of all, if you have both tickets already (the Fund and the Chamber), just go to the door with the shortest line available.
Second, if you have tickets just for the Armory, you can buy those of the Diamond Fund right in front of the Fund's entrance here:
It is right right on your way to the Armory museum. There's a little lobby from where a staircase leads to the Armory Chamber. But to the left from that staircase is the entrance to the Diamond Fund with a reception desk where you can buy tickets right on the spot.
And third, if the opposite is true, and you only have tickets to the Diamond Fund instead; then once inside, you can backtrack all the way to the 'official' Armory entrance that people were lining to outside. And right next to it you'll see another ticket office, similar to the ticket windows in Alexander's Garden outside the Kremlin.
That ticket office has a gigantic lunch break from 12 to 2 PM, and it'll likely tell you that it only sells Armory tickets there when there isn't a big line outside the main ticket office in Alexander's Garden. Sort of, that so many people are left there without tickets every day, it would be total cheating for you to buy them here. And you normally can buy them in this window only if something is not sold there outside.
But the definition of that 'big line outside' can be very malleable, and there's always some chance for you to get them just by being extra nice and saying that you always dreamed of visiting the Armory and going outside fro those tickets is going to take too much time.
Even I've got them like that about 2 out of 10 times, when they originally refused to sell, by saying that it's just two tickets, and it's not going to end the world for people waiting outside. And considering that all employees of all big state museums in Russia tend to be muuuuuuuch, much nicer to foreigners than to Russian people, you should have even a higher chance of succeeding.
Mega hat trick to beat the line to the Diamond Fund
This doesn't have a high success rate but feels extreeemely satisfying when it works. Quite often lines to both the Diamond Fund and the Armory entrances outside the building are not synchronized. When there's line to one, there's often almost none to the other.
So, like I said, if you have tickets to both of the museums, just pick the entrance with the quickest line.
But you can also try to do that with only Diamond Fund tickets in your possession. You have to have a correct pre-requisite though.
You see, if you have heavy winter jackets, big video camera or umbrella that you won't be able to hide in your purse. Then they'll send you all the way across the building to store those things in the local cloakroom. The cloakroom that's very close to the other entrance that people line up to with Armory tickets.
So if you see a huge line to the proper Diamond Fund entrance, you can try your luck going inside the building through the Armory entrance by showing you Fund tickets. She's, technically, not supposed to let you in. But if there aren't many people at the moment, and she has time to properly process what you're trying to say; then if you say that you have a big umbrella they told you to store in the cloakroom that is much closer to this entrance, and that doesn't make any sense to walk all the way back inside the building later, and if you're being all that nice and constantly smiling foreigner, then she miiight consider letting you in. Because yes, rules are rules. But what you're saying should make a lot sense to her in this situation.
If it actually works, take a second to glance one more time at that huge line at the other entrance, and with the full sense of superiority proceed inside.
And this will be it for 'buying tickets inside the Armory building'. I hope it helps. Please share the article everywhere you can if you liked it.
Thanks for reading!