I had no idea how to do this and work happened, sorry for the delay.
With the vz.70 unchanged, the vz.70 will continue through without much in the way of new testing.
The Modified Rivkes was put through its paces and performed roughly on par with the previous variation. The action was a bit more reliable and user friendly, and suffered fewer malfunctions than the standard Rivkes with or without the higher quality magazine. Accuracy at 3.5 MOA was comparable to the highly worn-in testing example, but was significantly below the 3 MOA it should have achieved new due to the much heavier trigger pull. The gun was safer to drop than the original with the safety off due to the heavier trigger pull but identical with the safety on. Hitting a fleeting target or switching fire modes was made significantly more difficult given the placement of the selector switch, and the almost doubled trigger pull throwing off the shooter's aim. However, the newer rifle is easier to settle a new user on and has fewer quirks but is actually less well liked because of the comparative difficulty in switching between bursts and single shot even with the trigger lightened up.
Stoppages per 1000 Rounds
Standard Rivkes/Standard 20rd magazine – 3.1
Standard Rivkes/Improved 20rd magazine – 2.5
Modified Rivkes/Standard 20rd magazine – 2.7
Modified Rivkes/Improved 20rd magazine – 2.3
The revised Holl 875 didn't require much testing, given that the main difference between the two is the charging handle. While the standard 875 and 875.1 have a charging handle way forward by the front sight, the position is apparently more ergonomic and provides significantly better leverage than the reciprocating charging handle on the revised model and could be easily charged by mere mortals as opposed to Lindor Holl or an Orthopaedic Surgeon. Needless to say, as the newer handle has half the leverage of the older handle fighting the lockup of the action is significantly harder. Reliability and ergonomics were otherwise identical between the two models.
Comparing the 875.1 however was an interesting mix.
The Revised 875.1, featuring a vertical front grip and the modified charging handle, the Standard 875.1 and the vz.70 were put to the test in a three part course set up on a shooting range, which would include a mix of light cover, prone shooting, and a couple of hastily assembled pieces of cover. Namely a waist high CMU wall and an old refectory table with some plywood on it to serve as an ersatz-pillbox, as well as a brief walking fire segment.
The vz.70 performed well across the board, as was expected, and was easier to load while prone, although the ersatz pillbox was a bit tight if still serviceable for reloading given the limited vertical dimensions. This would not be an issue in most circumstances, as both real pillboxes and houses have significantly more vertical space.
Both 875.1s served fine in the braced sections, with the bolt hold-open keeping the Revised 875.1 from being too difficult to use. However, it was noted that the vertical front grip made it harder to place the Revised 875.1 on the CMU wall, as it had to use the bipod instead of just resting the receiver on a surface. Either way, the crew was somewhat used to the quirks of the 875.1, and would do something nicknamed the "Holl Roll" to exchange magazines without breaking the sight picture too badly.
The main difference in the performance of the two 875.1s was in the walking fire segment. While it was more or less impossible to fire the standard 875.1 standing, the revised 875.1 was actually fairly easy and comfortable to shoot with the bipod folded out of the way (with the bipod unsecured, it had a bad habit of bashing knuckles.) Magazine changes and barrel changes while standing were a bit easier than on the standard model as well because the vertical front grip gave a good amount of support and made it easier to keep the weapon held tightly to the shoulder while the right hand manipulated whatever needed to be dealt with.
With all this testing completed, further modifications or reversions can be made, in preparation for final testing and possibly adoption ideally by the second quarter of Year 15 of the Revised Kubachi Calendar (it is presently Year 13 Q1.)