Zastava uses a very soft, type of hardwood for their stocks.
Not sure what it is but it isn't Walnut nor Birch(Beech)
When they made the 798 rifles for Remingon, they had an agreement to use Remington supplied laminated stocks, which may have been supplied by Boyd's (that's just a guess on my part)
Their later M70 models could be ordered with composite plastic stocks that were quite good as well.
Whatever wood they made their earlier imports from was very prone to warpage and loosening up in the bedding. Every single one of those stocks would really benefit from a good epoxy bedding job.
Boyd's makes a lovey laminated replacement as well as solid Walnut stocks for both models and they definitely dress them up.
I like the last imports of Zastava rifles much better than the earlier imports. Especially the trigger groups.
The Zastavas can definitely be improved with an after market trigger. Finding a trigger for the Mini action can be difficult, but a standard 98 after market adjustable trigger can easily be fitted.
I've had a couple of their offerings and liked them both. Found them to be quite accurate.
I've also purchased a couple of the barrels from Intersurplus, which were made by Zastava. Only non standard options left now.
Mark, be extremely careful when adjusting the trigger pulls/let off/overtravel on those triggers. The early rifles, which your rifles appear to be had a lot of what appear to be ''hand made'' parts, which are very soft and easily galled or damaged/broken.
I've had to repair several of them already. Later imports seem to be better quality.
These rifles are not expensive and IMHO well worth every penny as a utilitarian firearm.