1. Use the Hodgdon OAL listing if they mention it. Otherwise, just seat to nominal OAL per the cartridge specs.
2. Does the Sierra manual, etc. really say the bullet is listed for maximum impact velocity of 1350 fps? What's your target? I believe that with critters up to coyote size, you'll have spectacular wounds and quick kills at shorter ranges, with a lot of hide damage. For "social" use, you could have either M16-style stopping power at 2000+ fps, or you could have failures to penetrate enough. As downrange speeds drop, it could be superior to std M1 carbine ball for stopping power, but that's not saying much according to reports I've heard.
3. In-flight stability should be great, as even the 110-gr. has a stability factor several times the minimum needed, at 1850 fps. A shorter, lighter bullet will be even more stable. IF you melt the core at extreme velocities from barrel friction, you could have mysterious "blue cloud" bullet blow-ups mid-flight, but I've never heard of these below 3500 fps.
4. If Hodgdon lists the load, the powder will almost certainly ignite reliably under that bullet. Since H110 is rather slow for pistols but fast for rifles, *reduced* loads are the only concern IMHO.
5. If it works for your intended target, this load could be an ideal urban social use/dense rural pest use load. Check out the downrange ballistics and see how short the max range is, and how pathetically low the velocities/energies are beyond 1,000 or even 600 yards...