Episode 5 - Norman gives 'special bullets' to the Jackal and Duggan's flashback of Gary

In episode 5 at 29:35 Norman hands over a case of bullets to the Jackal to test out the 3D-printed sniper and says "Couple of special ones in there, too". Later on at 33:05 when he is about to shoot the watermelon for the 4th time - the camera focuses on the bullets in that case there are 2 bullets with a silver tip image attached**;** (and it seems like he is rolling it in his hand for a bit too long - like thinking about something)

Am I missing something about how these "silver-tipped bullets" were special???

My guess is that Norman and Duggan have some history together but they have never met one another because Norman says "You are taller than I imagined - and slimmer" when he comes to pick up the Jackal to take him to his place.

Question 2
In eps 5 again, at 19:53 Duggan stops and stares at a sniper (image attached) at Norman's place and then has flashbacks about the wedding and Gary but upon analyzing and trying to match that rifle from Eps 8 (where Duggan's history and Gary is shown) neither Duggan nor Gary have used that same rifle because that rifle has a different Buttstock compared to what both of them are shown to use throughout eps 8 (image attached)

What are your guys' theories about this??

I am 100% positive that we would get to know how Duggan and Norman came into contact in the first place and maybe also shed some light on what was the "2018 Stockholm Assassination" that Bianca mentions a couple of times in Eps 1 - maybe Duggan and Gary were partners in that Stockholm Assassination - who knows? And I think that Gary is who Duggan wants to find when he tells Zina in the very end of Eps 10. He wants to find Gary first - eliminate the Charles Dance guy for the unpaid debt and then find his wife and child in a parallel way

Apparent special bullets given to the Jackal by Norman

Sniper at Norman's place - notice the Buttstock

Gary's rifle on the left with a completely different Buttstock (Duggan's rifle is totally different as well)