I'd bet a large majority of those ARs at your ranch aren't properly lubed/greased. It's so common that the huge majority of courses I've taken and taught, that doing a function check at the start of day 1 shows that nearly every AR/AK user hasn't done this for some reason. Clean is one thing, greased/lubed is another. And, if you run either of those rifles hard, as in training hard, like 1500 round days, with some 2 to 300 round evolutions in those days, the major cause for failures is lack of properly lubing and greasing the rifle in proper places. I'm not saying there aren't other causes for stoppages and failures, just that there is a systemic problem in the semi auto rifle shooting community to NOT do this right for some reason.
Proper method IMO -
https://www.youtube.com/watch?v=rzVr7JXVxH4Also, in areas like you describe in Texas, and in the mid east as well, there are products you can use specific for that kind of dust to make rifles more resistant to problems, but it's still IMO one of the hardest environments to keep a rifle functioning well, fine dust that's airborne a lot due to wind.
I have a 545 Krink rifle as well - it's not a true Krinkov, but a kit put on a full sized rifle, so close enough. We rented it on our range for years back in the early 2000s. Loud, big flash. Never had a suppressor on it though. I've never owned a Valmet, but i've shot the M76 in 556, excellent rifle, reminded me a lot of my tanker Galil. Love to grab a heavy barrel Valmet M78 too if it was possible. A few pop up for sale up here from time to time, missed this one last year when it went for 4500$.
