That. The next closest to flush fit (AICS is my only consideration) is Ruger's 3 round poly mag....it sits a little further below the stock line than the Curtis Custom but not enough to make a difference to me. After using multiple mags from different makers in various platforms this past year while hunting and shooting...especially while hunting....if I don't need the extra COAL I like the Ruger better than any of them.
I know HS-Precision makes one, but any others out there??
(This would be used on a hunting rifle)
The old HS Gen1 magazines were a beveled flush fit. However, IIRC, the current HS Gen2 magazines actually protrude approx 3/8" to 1/2" below the stock line. Some folks complain about the old HS Gen1 mags. However, I have never had any issues. Got go looking to find them, though...
If you're using a 700 long action or short action, Kwik Klip had a nice drop-in that I've used in the past with no complaints; however, the LA mag box is limited to SAAMI COAL for 30-06, and the SA mag box is limited to SAAMI COAL for the 308.