Various pistols have 10, 12, 14, 15, 19 round magazines. They were built that way from the beginning.
The AR15, M16, and variations are all based on the original design, which uses a 30 round magazine.
An M14 (aka M1A1) was designed to use a 20 round magazine.
I don’t know where to draw the line between “slightly increased capacity” and “significantly increased capacity”, but an 8 round magazine will fit entirely inside a 1911 pistol, which was originally designed to hold 7 rounds. It’s actually the same magazine body, just with a thinner spring and lighter follower. A 10 round magazine does stick out of a 1911 by a couple inches, and a 30 round straight magazine in a Glock pistol appears to hang down nearly an extra foot. The Thompson submachine gun was designed to handle both 15 round stick magazines and 50 round drum magazines. While most hunting rifles that have detachable magazines have been sold with 4, 5, or 7 round magazines, 10 to 15 round magazines have been available as factory accessories from the outset for nearly all of them.
So on and so forth: hundreds and hundreds of models of firearms have been built from the ground up to carry more than 7 or 10 rounds internally. Heck, there was even this gun - the Calico; it came in both pistol and rifle versions - that used a screw feed “helical” top mounted magazine that could hold 100 rounds. ONE HUNDRED ROUNDS. And that was normal capacity for that firearm.
Fight the meme. 7 or 10 or 12 is not high capacity.

The original M16 mag was actually 20, and Eugene Stoner raised hell at the demand for 30s by the troops because of the 30s the AK47 used, but 30 has been “normal capacity” since the mid 60s. Mikhail Kalashnikov had his turn to bitch when they wanted a smallbore in response to the 5.56x45, and introduced the AK74. That 5.45x39 is a devastating round.
I just KNEW one of you would bring that up. I’m so proud, really I am. I love it when my readers show that they know their stuff and are not low-information voter types.
Thats what DU and Kos are for Drew, the No-Info Voters.
Glock gives me wood.
Ill bet if you held that up in front of Obama he would faint straight away the Fag.
Actually - The Thompson was issued with 20 & 30 round mags during WW2. The drum was considered to heavy and had the potential to case damage to the mag support.
Owning all of the above (AR15, M14SA, Thompson Carbine & Glock 21) I am saddened that my state does not allow 100 round magazines. I’d love to show up on a range with that!