As I found, the Barnes TTX bullets have a "curvy", tangent ogive point with a small "flat" hollow point. If seated out to the max oal the M1910 magazine allows, the bullets are held reasonably close to the follower spindle by the bullet guide. Yes, my loads work in the M1910 magazine. Granted, the Hornady RNs worked a bit smoother, but there is little choice now.
Such pure copper bullets are much longer than conventional lead core ones of the same weight. The 235 gr TTX is longer than the 270gr RN, but seated out in the 9x57 M-S = .375 Rimless NE it just fills the case neck. The longer 270 gr TSX protudes into the case body, eating up powder space. So I could not load more than 50 gr N140 behind the 270 gr TTX, giving away a lot of velocity. My load, with the 235 gr TTX in front of 55 gr N140, reads out 2400 fps from my 50 cm = 20" barrel over my chrony.

Thank you so much, Kuduae.

This is exactly the information I have been looking for, and from a trusted source.

Mine is an M1910 of the Steyr 'Takedown' configuration.

Surely, you'll recognize this (your own M1910).

Here's mine (Granddad with M1910 at center).

Have you, by chance, any experience using IMR4895 with the barnes copper projectiles? I had been running 42 grains of it behind the Hornady 3715. It's been some time since I reloaded, but I have recently laid in a supply of the IMR. Perhaps I can find a 'conversion' for (x)N140 = (x)IMR4895.

Again, I thank you sincerely for the reply and valued information,
Brian Rothhammer