Wild,

a 9 incher would certainly be an interesting project.

As to barrels and comps, in these link/cam guns (1911 and Glock) the brake needs to be a barrel brake, not one of the slide types. The mechanism of why they work is the brake helps keep the nose of the barrel down a tad longer, and pushed forward both helping to delay the unlock. Down is obvious as the gasses vent up, but forward is a little harder to "see'.

On these actions where the slide and barrel move to the rear and unlock, the bullet moves down the bore while the slide and barrel (locked together) start to the rear. As the bullet is moving down the bore, the friction of the bullet in the barrel essentially drags or pulls the barrel forward. On the comps usually used for these, the expanding gasses in the comp vent up pushing the barrel nose down, and the gasses push forward on the rear vertical edges of the comp, again pushing the barrel forward.

In theory, the 9 inch barrel would have more weight in front of the link/cam point, possibly supplying more upward pressure behind the link on the upper barrel lug, and the longer barrel would have more bullet "drag" time. Both of these should work to your advantage.

Might make for an interesting project.

Craig