Respringing for minor loads

[grywlfbg]

Ok everyone, so I'm new to Open and to 2011's so be gentle.

I picked up a lightly-used Brazos ProSX. It's set up for 9-Major w/ a Recoil-Master and mainspring of unknown weights. I only shoot 3-gun so power factor is not an issue. I'm planning to shoot 115gr bullets with a slow powder (currently using 7.4 gr of 3n38 in my CZ open gun). Since this gun has poppelholes I stepped up the charge to create more gas (with its current setup it won't reliably eject the 7.4gr loads). I have some 8.2gr loads worked up and they are very reliable and accurate.

However, the gun feels like it bounces around a lot. The initial hit is harder than my CZ (though my CZ is much heavier so that's likely most of it) but the bigger problem is that the dot really bounces around before it settles down causing my splits to be pretty slow.

After doing some reading here I'm wondering if the gun is oversprung for my minor loads. The seller told me he was also planning to shoot Steel Challenge and included a standard guide rod, reverse plug (I think that's what that extra piece is), and a few Wolff variable springs (7lb, 8lb, and 9lb) that say Colt Commander.

So my first question is, Are these the right length springs for this gun?

After my reading here, this is how my plan is shaping up - please provide a sanity check.

1) Install the standard guide rod and plug. Doing some test fitting tonight the rod sticks out a 1/8" or so under the comp. I assume this is ok or should I have it cut so it's flush?

2) Should I bother with different mainsprings to get the lightest one that will reliably fire my loads (I use Fed 100's)? Though from what I gather it's not feasible to change these at the range?

3) Try different recoil springs. I do not have any shock buffs. Should I go for the lightest one first or start w/ the heavier (9lb) one and just see which one feels right? What will I break if it's undersprung? Just the slide stop? I could have a spare one of those in my bag. Anywhere else to check for wear/damage if the slide goes crashing to the rear? Should I add a shock buff?

Thanks!