Quote Originally Posted by Artfull-Bodger View Post
No that's an old wives tale, the foresight grooves have no effect at all, I have several HW barrels here ungrooved and grooved and they are all choked, you can buy HW blanks from silco that are choked or unchoked with no grooves in them and if you measure it the choke is in the same place even when there are no grooves, you specify whether you want the choke.

http://silco.co.uk/categories/WEIHRAUCH-BARREL-BLANKS/

I have no idea where this notion crimping a pair of grooves on the outside top of the barrel creates a tight spot but suffice to say it's a nonsense, the barrels are actually choked by design.
Thank you. I did not know that, and had accepted the old wives tale. Tbh I had also wondered how machining the grooves creates a choke...