Kriss Vector Accuracy 45ACP

I modded a pistol to a 11.25 inch OEM barrel(all legal) to optimize the 45 ACP ballistics. It has a Vortex FH. It was built to match and go head-to-head with my AR45 with OEM internals.
The first test shots at 30yds were the typical 2-3 inch groups everybody gets. When I attached my Magnetospeed to the FH(to do some velocity tests) the groups went down to 1 inch (?), sparking the beginning of a Kriss Vector quest for accuracy.

The root of the problem is the barrel resonance of the 17mm OD barrels at any length, clamping a weight(a Magnetospeed) to the barrel end sort of proved that out. I shoot 45 ACP at 1050fps typically, just under the speed of sound, which adds to the accuracy problems.

I added a simple(McMasterCarr) shaft collar(about 5 ounces) a few inches from the FH, under the shroud. It has a threaded adjustment that moves weight on the barrel. These things, barrel tuners, tune a barrel resonance so a bullet always leaves the bore muzzle at the same exact resonant position in space. Normally I would have said phooey to all this voodoo, but the results speak for themselves. I got my group size down to 1/8 inch at the indoor 30yd range, and I'm happy enough with that. I'm using Federal 45 ACP HST +P, and reload my own plinking ammo to that velocity. The Kriss Vector 'can' handle the +P but it's at the upper limit of the recoil system(I can feel the stronger buffer impact). And another thing,  the barrel tuner tunes for one specific ammo, other ammo types need to be tuned individually(not a big deal) the weight is threaded and adjustable.

In conclusion, the Kriss has what it takes for better accuracy, it just needs a $30 adjustable shaft collar to tune the barrel resonance.