I used to use a Mark III when I went shooting with my dad, and I hated it. Something about the feel of it in my hand just made me loath the gun. Also this may be a small thing, but I really dislike those magazines, the metal tab you have to pull down bugged me.
You're talking about the standard MK II. The MKII 22/45 has controls and mag release that mirror a 1911. Hence the 22/45 designation.
Also, 25yards is WAY too long a distance to expect a novice handgun shooter to hit anything reliably with a centerfire handgun. Try the aim small miss small philosophy for a while and see how that treats you.
You really should be practicing at distances of less than 25
feet. Focus on creating consistent groups. Once the groups are consistent, focus on shrinking their diameter. When the diameter becomes less than fist sized, speed up your strings of fire.
Your intermediate goal should be the ability to draw and fire a fist sized group at 7-10 yds in less than 5 seconds. Once you have this down, the next step is to increase speed incrementally while maintaining group size.
Get some quality instruction and things will progress much more smoothly and rapidly for you.
Learn the 4 count draw stroke and practice with an
EMPTY gun for many repetitions. Use the same
EMPTY GUN and get regular dry-fire practice with it. This will make you a better and safer shooter.
I really like my G19 and I am accurate with it. However, different strokes for different folks and all that. It may work for you, it may not.
But if you do not intend to reload ammo, and you make less than a six figure salary, you need to get a .22 pistol. That is the only way you will get enough practice to become proficient, let alone competitive. Also handgun shooting is a very perishable skill, it requires frequent practice to stay proficient once the fundamentals are mastered.
Good luck
JH