Have a 26" Browning BPS Inv+. Which PureGold choke construction would you recommend for this gun shooting 3.5 2oz Win Longbeards in #5s. General consensus on here seems to be .670 but the majority of testing I see is people using HTL in #7s.
First :welcomeOG: I shoot a PG choke in my 835 and Love the results I get. I do shoot the Hevi 7's as you stated. According to the PG website https://puregoldchokes.com/cgi-bin/commerce.cgi?search=action&category=INVH, you only have 2 options .660 and .670 for your BPS. Since the LB's shoot such a tight pattern and you are planning on shooting the 2 oz #5's, I would go with the .670. I believe the .660 will be too tight for the LB's. Most of your choke manufacturers have done extensive testing of their products with multiple guns and shells so I would contact them and ask for their opinion. They have their E-mail and phone number on the website.
http://oldgobbler.com/Forum/index.php/topic,70208.0.html
I shoot the pure gold with the 670 and a SX3 with a 26 in barrel and LB #5 check out the pattern on the 3 1/2 inch shots.