The JSB are barely 4.50 with the majority being 4.48, 4.49 and very few over 4.50 . The AAs at least have quite a good amount at the 4.51-4.52 heads on them. Mike
My TX200 I use for FT likes them. Makes zero difference if they are JSB or AA version of the 8.44. I always order the 4.52 head size. I shoot them straight from the tin. I agree when running them thru the Pellet Gauge they are not nearly as consistant as the CPL pellets out of the brown box I have gauged. I typically use the AA version as they are cheaper than the JSB labeled tins. No other reason. I would gladly shoot the JSB 8.44 if the cost the same as the AA 8.44.When it come to pellets, quality pellets from any brand, I tend to think you need to look at quality over a long period of time. In my mind the pellet factory could be cranking out thousands of great pellets day after day and then Joe Blow, the pellet master, goes on vacation for a week or two and things run amuck and thousands get out that aren't up to snuff. Or Shiela the head pellet inspector gets the flu and is out for the week and her underlings just let whatever thru as they are looking at Facebook on their phones because the boss is away. Or maybe the pellet machines get out of wack, just a little, and thousands of pellets get out before they figure it out. I really wish they would put a date stamp on the pellets letting us know what day they were made. Then if people got on here with complaints we could compare the dates they were made. I bet, and maybe I am just stupid, that we could all buy a certain pellet from different suppliers and if we were all to inspect them for quality the bad tins were made on a certain day or a defined date range. I am talking quality pellets here and not crappy ones where they don't care and crank them out.
ncedMy bore in the B40 mirrors your with being loose and finding that only CPLs and 4.51-4.53 JSB/AAs. My bore may be a bit looser than yours since it really like the boxed CPL I have from die 7 dated Dec 14 2004. I am about out of the CPLs so tried some 4.53 JSBs only to be very disappointed in sizes and consistency. I found that the 4.53 H&N FTTs are far more consistence in size and shoot very well from the B40 so those will be my choice from now on. The CPLs also measure the 4.53-4.55 that you have recorded. But from reading about the newer CPLs being much like the JSB/AA QC. I am hesitant to buy a box from todays dies for that reason.All my other .177s shoot the JSB/AAs fine so at least they are not going to waste.Mike
So far, my 177 Bantam Hi Lite likes the JSB Exact 8.44 grain pellets the best overall for 25 and 55 yds (from 17 different pellets and sizes); 10 shot groups, 8 mph wind, 38°F, ~883 fps.25 yds .48" CTC55 yds .81" CTCSitting on a stool, in the corner of my deck railing, front bag rested, each elbow testing on the railing on the corner (sort of like a "bucket and sticks" Field Target hold). This is all from using my single shot tray. Magazine loading can be double these results.Today I tested two head sizes straight out of the tin at 25 yds.4.52mm .48"4.53mm .83" (73% bigger)Last night, I tried using my $7.50 digital calipers to measure accurate head sizes. Sadly, I could measure the same pellet 10 times and get 6 different widths. Either my process or my calipers (or both) are inadequate to this task.It seems strange to me that two tins of the same pellet that are marked as only different by .01mm should produce such radically different group sizes.But there you are.