I'm really struggling with the deep/shallow skirt on JSBs.
When I first had the gun, I got hold of as many different types and batches of pellets as I could and found that a 4.53 variant gave the best groups.
I realise that stated head size bears any correlation to pellet size, but ever since I have always used 4.53s and whenever I have had to change batch I noticed that the POI moved slightly but, after re-zeroing, the groups were pretty typical of what I achieved previously.
Recently however, I have had 2 sleeves of 4.53s and 1 of 4.52s, both of which have what I would consider a shallow skirt. There is a notcieable 'flat' in the base of the pellet, so even though the pellet is a similar overall length, the depth of the recess inside the skirt is considerably less.
These pellets are terrible in my gun, I need to add something like 10 clicks at 50 yards, and the groups are considerably worse. Looking at the info in previous posts, I guess this suggests a lower BC. The gun also feels like it has much more flip.
Does anyone know if this shallow skirt variant is the new 'norm' for JSB or is it die dependant?
When I spoke to Ryan at Intershoot, he didn't have any batches of the deep skirt variant in stock.