Everywhere I look the 45 Colt 20" barreled Rossi 92 shows 10+1 rounds, however I can fit 11 rounds of 230gr. HP ammo in it and if I put 7 rounds of the HP ammo and 5 A-Zoom snap caps I can load the tube to 12. I'm not forcing the rounds in and I've only put a few hundred rounds through it so the tube spring isn't worn out. The only mod to the tube is a SS follower.

I'm not one to load over the factory capacity, but loading the 11/12th round is as easy as the first and they all cycle perfectly. Anyone notice this or am I experiencing a fluke?

Never mind ... I didn't read the OP very well.

230 grain loads, especially hollow point loads are shorter then typical standard .45 Colt loads.

Snap caps are just that: snap caps.  In no way do they replicate real ammo.
For that you'd need Action Proving Dummies. available from Brownell's.  These do replicate the exact size, weight, and even balance of live ammo.

In short, like most tube feed firearms, you can't over stress the spring unless you try to jam in rounds when they don't want to fit.
Since your ammo is shorter, the tube will hold at least one more round.

I have the 16" Rossi .45 and I don't recall how many mine holds.  Maybe 6?  However it will not feed flat front bullets like the 270 grain thunder heads.  The bullets hit the back of the chamber on the top lip and won't slide in.  Pain in the butt to remove from the rifle.  Single feeding flat fronts works from the top.

Thanks for the replies. I figured it would be set where even slightly smaller bullets could only be loaded to 10. Nothing wrong with an extra round I guess.

Depends upon if you've shortened the mag spring per Steve's Gunz DvD or not.  I have both a 24" and 20" Rossi in 357mag and they can hold 15 and 13 respectively.

A newer stainless steel Rossi .44 mag holds a politically correct 10 rounds in the tube....an older rossi M92 in .44-40 holds 11 rounds

If it has a plastic follower it's probably a 10 shot

No spring modification and a steel follower. No other mods have been done. Thanks for the input everyone.