Shotgun-Insight . . . . summary of results
B25 Sporter with 1/2 choke . . .
Because a sporter will be used at varying distances there is no standard distance at which pellet coverage can be compared. Therefore the key measure is repeatability of the spread. Also, for fixed choke shooters knowing whether a shell shoots relatively tight or open is useful knowledge and by altering shells can be used to give a wider range of available spreads. Hunters may also want to know which shell on average shoots tightest in order to offer extended range (even if repeatability is not the best). Another figure of merit is how close to the expected pellet count the shell actually is. Unless one is prepared to count the pellets in each type of shell and then check a chosen shell periodically to make sure it hasn't changed, one relies on the manufacturer to put the expected pellet in the shell! If it says 7.5 one would expect ~400 pellets in a 28g/1oz load.
Average spread summary at 25 yards for 30" B25 Sporter with 1/2 choke (Teague long choke).
Considering the 28g loads first:
The change in the Express HV 28g pellet count was covered in the main web site, ditto the Express World Cup. A more subtle effect is now considered with the Hull ProOne 28g load. To give improved confidence when comparing the Hull ProOne with the Hull DTL300 additional shells were tested beyond the original ten of each. The table above shows the average spread and variance but the detailed plot below of how each shot compares with the average is a little troublesome.
Hull ProOne & DTL300 spreads over 18 shots over three days.
The bold straight lines show the 18-shot average spread for each shell. The DTL300 is pretty well behaved with single points either side of the average throughout the test and a large number near the average. (Note that even though the DTL300 is one of the more repeatable shells the extreme spread of smallest pattern to tightest pattern is still large - certainly larger than a choke size and larger than differences between the average spreads of shells. This is why looking at only a single pattern can be very misleading.)
The spread of the ProOne versus time is more worrying. The average over 'Day 1' and 'Day 2' is much higher than that over 'Day 3'. Is the shift due to temperature, a different 'recipe' for the second box of ammunition or just natural variation and a fluke that most of the shells on day three shot tighter than earlier? Express Olympian 24g were also shot over 'Day 1' and 'Day 2' and these also appeared to behave differently - shooting tighter but less repeatable on 'Day 3'. This didn't affect all shells though, witness the DTL300 load above and also Express HV which was shot on 'Day 3' and performed similarly to Express HV shot on another day (see later).
If the change was due to temperature, since you can't control the weather it's best to pick a shell that is relatively unaffected. If it's due to random variation, pick a shell with smaller shot to shot variation. Either way, the DTL300 performs more predictably than the ProOne load. Ditto Express HV versus Express Olympian. Maybe its coincidence, but both the DTL300 and the HV have slightly lower muzzle velocities than the other shells.
Express: HV No.8, No. 7.5 and Olympian shot to shot variation. (Olympian shot over two days)
Referring to the graph above, the bold vertical line shows the break between shooting two sessions of 9-shells of the Express Olympian cartridge. Just as with the Hull ProOne (shot on the same day) the latter set of shells group tighter than the first. It could just be chance, or it could be temperature. Either way, the Express HVs didn't miss a beat. On the graph above all 18 Express HV 7.5 were shot on the same day as the second set of nine of the Olympians. The eight Express HV No.8s were shot on the same day as the first batch of Olympians.
Shown below is a chart showing the relative costs, average spreads and shot to shot variation (shown by the size of the circles).
Performance of 24g 7.5 & 8 loads vs cost. (size of disc illustrates shot to shot variation - smaller is more repeatable)
The Express HV loads stand-out as being the lowest cost, with a tight pattern and the lowest shot to shot variation. The Hull Chevron is also looks good value for money, it is also incredibly mild on the shoulder but not widely available so unfortunately most people will not get a chance to try it.
The B25 is relatively light so the Express HVs make a great companion. The No.8s are my choice for close to intermediate distance targets. The only drawbacks of the HVs are that they tend to leave a lot of plastic in the barrel (this also happened with the Beretta DT10 and also happens with the Miroku) and there are only 14 pellets difference between the 8s and 7.5s! For longer shots the DTL300 with its tight consistent pattern but modest recoil is the choice.
(c) Dr A C Jones