Reply To: Optimal Velocity for JSB .177 16gr out of LW Polygonal barrel
Forums › Pellets, Projectiles, Slugs, & Ammo › Optimal Velocity for JSB .177 16gr out of LW Polygonal barrel › Reply To: Optimal Velocity for JSB .177 16gr out of LW Polygonal barrel
Certainly could be some generalities to be made, however I would never discard potential. Ive found that some shoot ever better slower, when not accurate at faster velocities. Why? Barrel diameter, twist rate, etc??? There are a few discussions regarding this on GTA, but take a look at post #2 on this thread: http://www.gatewaytoairguns.org/GTA/index.php?topic=118462.msg1153180#msg1153180
The greatest velocity I could achieve was just over 700fps with that set up but for only a couple shots before dramatic drop in velocity. So my 5 shot group was like 675fps for 5 shots using the .22 33gr JSB. I dont know what possessed me to even try this, as I bought those to shoot in my Sumatra and Condor. Twenty-yards went so well I push it to 40yd. I posted two of the groups, but they were all like that. I was so surprised and having so much fun (just dumbfounded by this little HPA QB78) I put hundreds down th barrel that day.
Then just recently, I took that rifle out again to try some others, as I prepare some targets for my new adventure, heavy .177 long range. So I was shooting the 25gr .22 JSB the exact same as the 33gr. I had actually tuned it for the Baracuda Hunter, but was getting occasional flyers so went to the 25 gr JSB. Its shoots these at around 720fps. So this is my go to, as I want to hit a but harder out to 40yd (tested 15gr and 18gr as well).
Long story long, I think you can shoot them a little slower with success. My guess is, more to do with the barrel, as mentioned eg twist, land/groove, choke to shoot more cylindrical projectiles. For example, look at the Sumatras and of course many slug shooter can be quite accurate shooting cylindricals at lower velocities as well. I ordered the heaviest H&N other than Piledriver as well as the JSB 16 .177 and hope I have something more to add after this weekend.