Hey Bill, the JSB are 18.13gr the last time I checked, lol. Unless they did change them, it's been so long since I bought any, they might have.I was referring to the 250z, sorry LOL. The last thing I did with the Marauder prior to removing the stock was move the target back to 75yds. Unfortunately with the JSB 18.3gr pellets the groups really opened up. The Apolo slugs did good at 50yds. I need to finish the stock and then try some others. I’ve spent most of my time working on the GSX-CS4. The Walmart NSA did terrible in the Marauder. They have 216 in the part number, makes me think they are too loose.