How good does it need to be, really?

First topic message reminder :

Hopefully, the Master class folks who stumble across my tale can educate me. Even knowing the falsehood of the marketing heaped upon the Colt Gold Cup, I bought a few of them. I have had one off and on for over 35 years. The longest I could put up with one was an 8 year period while shooting 50-yard pistol metallic silhouette in the tropics of south east Texas. Luckily, the targets are relatively large, and relatively close.
Thanks to this forum, and the opinions within, I became smitten with the desire to start a re-entry into Bullseye by purchasing both .45 and 9mm Gold Cups. 
Why?
In order to provide a myriad of mechanical challenges while testing my patience, now that I am retired. I like to know how mechanical devices function. Holley carbs, Rochester Quadrajets are things kids today cannot describe. I learned to rebuild them through exposure and trial and error. Pre-Internet.
I have recently met a few folks who like the challenges of Bullseye, and have been encouraged, as long as I am spending my money and time of course, to endeavor to persevere, like the 
Indian in The Outlaw Josey Wales.
Starting off, none of the four Colts would group 7 rounds in the black at 50 yards. I received many helpful suggestions, so started off by establishing a decently accurate load for each Colt. Next came hard-fit bushings from EGW and Bailey, with an acceptable improvement in accuracy. But not enough accuracy.
My .22 is a Pardini SP-22 from 2005. A tough gun to measure up to.
The next step up was a pre-fit Ed Brown barrel for my Combat Commander, my CCW pistol.
Since it was in need of improvement, it was a test case. Ed makes no secret that his barrels require plenty of file work. They do indeed, but the results were nice enough to give me confidence to continue on.
KART next provided an EZ-FIT barrel and bushing in .45. Internet Claims of a one-hour installation make me wonder who is zooming whom. The Kart gets shot each range trip, and has proven 100% reliable and groups less than half as large a group as the pistol did from the factory.
My toughest task to date, a KKM in .45, requiring hours of measuring, many trials of file and assemble, file and cuss, file and assemble. This pistol is my favorite blued NM without Beavertail, but it had the benefit of a KC Kustom CMP roll trigger at 3.5lbs. What a joy KC’s triggers are! 
Once the KKM barrel was fit, I needed to Finish Ream the chamber. KC offered to do this task, but being OCD, I decided to buy a reamer and proceed. Might as well, since he is covered up in work, and I have four pistols that will be getting the same treatment eventually. Thanks KC!
Briley was my choice for their spherical bushing system. I had high hopes after completing the barrel,  and hard-fitting the bushing to the slide.
Today was Finals Test day for the Colt. I had a whole hour and fifteen minutes to set up my shooting box, hang a couple of targets at 25 yards, and function-fire and then sight-in the Colt. I had 20 rounds of Magnus 185gr. LSWC available, and more ZERO 185gr. JHP then I had time to shoot, ready to go. Function was perfect, other than some stovepipes from my weak loads, but the recoil spring will be of lower rating tomorrow.
Please inspect my target below, and offer criticism and/or opinions relating to the acceptability of this particular gun and load for use in the Bullseye game. 
I’ll have more time later in the week to test at 50 yards. While I am doing so, I will be trying out different optical lenses to see if they can help my 20/15 farsighted and focused at Infinity vision, since watching the front sight close enough to avoid the missed shots landing away from POA is troublesome with post-cataract man-made lenses. Still, it is better than my previous 20/500 nearsighted Coke bottle eyeglasses allowed.
Thanks to all you helpful folks. Much like being able to safely leave shooting gear and weapons out of sight at Camp Perry, and know they are in safe hands, this forum group always manages to provide honest opinions.

Same thing, depending on the amount removed from the bushing you will get a barrel shape or taper, and not round! I fit Briley bushings, I get over size and reduce the OD in a tool and cutter grinder using a Diamond wheel but lathe will work. I lap the bushing hole to insure it's round!