This is an old thread, I know, but one I will try to add to since it popped up bold in my feed yesterday.
I have been using and really liking Unis Ginex primers for a few years. I wish I could buy more, and I am guessing that it is all the p*ssing and moaning about size that has prevented any more coming in when we could all have used a fgew more primers. COVID (Thanks Pres. Xi) may have had something to do with it too.
The manufacturer's website is:
http://www.ginex.com.ba/ Bosnia was previously part of the country known then as Yugoslavia. If you pick through their website you will see these folk know their primers.
I bought 5,000 UG small rifle primers at Bruno's on clearance when no-one else wanted them. I have never noticed any dimensional difference with these than any other small rifle primer I use.
That's not true of their various large rifle primers -- the size is right on the box -- 5.5mm although the spec sheet says 5.4mm mas o menos. Sellier and Bellot advertise a diameter of 5.3mm
In a project involving the loading of .308Win IMI Match brass, which has notoriously tight primer pockets -- frankly if you don't have either Win or S&B LR primers swage the pockets, you'll save yourself a lot of grief.
I found that:
IMI Match: 0.2085" primer pocket, LC fired 0.209 and Fed 300Wm 0.210" primer pockets.
Primer duiamters:
S&B 0.2098; Win 0.2101; CCI BR2 and 250 0.211, Ginex 0.2115.
Yes, you can extend case usability using Ginex primers

Although, after most first firings they seat just fine and give really consistent results. I have observed the LR magnums are a bit harder/thicker. My Savage 112 Magnum doesn't like them at all but it has a rather short/light strike. Otherwise, they work 100% for me.