There is a balancing act in 1911s between accuracy and reliability. The US GI 1911s all date to WWII though many have been arsenal rebuilt over the years. The GI Guns were all built with a bias towards reliability. Realistically rack grade guns with ball ammo were capable of 3-6” groups at 25 yards.
1911 accuracy involves more than just the barrel itself. The bushing, link and locking lugs are all involved along with the slide to frame fit. Serious student is spot on about the guns being worn out overall.
Re the Meusoc Guns - they were routinely shot out / shot loose in training and re built. My understanding is they needed two guns for each shooter to ensure they always had a working gun due to the PMCS / rebuild cycle.
There are very practical reasons they embraced the G19 as soon as they could under the auspices of SOCOM.