JSB .22 Redesign

[Franklink]

What changed about the tune from the MRDs to the Grands tune?

Better breathing valve, shorter/stiffer hammer spring, and higher reg pressure. Basically more air, but also more air in a sort of quick pulse, versus the prior method of lowest reg pressure to make the desired speed. Less hammer tension on the shorter stiffer spring. Just judging by perceived cocking effort, it's not much different that most of what I've run before with the longer/weaker spring.

I expected the net effect of those changes to make it an air hog, but I'm still getting 30-32 shots per fill (versus the prior 38-40ish), and the report is surprisingly about what it was before.

Those are the changes but why in the heck they'd make such a profound effect on flyers or no flyers is the head scratcher. For sure need to do more shooting but those 5 cards (125 shots plus a few sighters each would make it 135-140ish shots) have me much more optimistic for Monster RDs, even if I don't understand the why.

(And no, I didn't take a Dremel to my valve, this is simply a different one. My OEM valve is still safe and sound, can revert back to it and everything else OEM if I decide to do so.)

 

[igolfat8]

@Franklink , That's awesome progress! Did you add the tensioned barrel system? 23" or 28"?

 

[sb327]

Better breathing valve, shorter/stiffer hammer spring, and higher reg pressure. Basically more air, but also more air in a sort of quick pulse, versus the prior method of lowest reg pressure to make the desired speed. Less hammer tension on the shorter stiffer spring. Just judging by perceived cocking effort, it's not much different that most of what I've run before with the longer/weaker spring.

I expected the net effect of those changes to make it an air hog, but I'm still getting 30-32 shots per fill (versus the prior 38-40ish), and the report is surprisingly about what it was before.

Those are the changes but why in the heck they'd make such a profound effect on flyers or no flyers is the head scratcher. For sure need to do more shooting but those 5 cards (125 shots plus a few sighters each would make it 135-140ish shots) have me much more optimistic for Monster RDs, even if I don't understand the why.

(And no, I didn't take a Dremel to my valve, this is simply a different one. My OEM valve is still safe and sound, can revert back to it and everything else OEM if I decide to do so.)

Just some generalizations here, take from it what might apply. These are based on the assumption the ending fps are the same.

Higher initial pressure (reg) = lower muzzle pressure

If your shot count is the same and you base that on when you come off the reg, the higher reg setup is more efficient since it has less headroom to work with.

Harmonics have changed quite a bit, so that could play a big part as well. (Not just barrel)

Dave

 

[Franklink]

@Franklink , That's awesome progress! Did you add the tensioned barrel system? 23" or 28"?

These results are from a .22 Taipan Veteran. Although with non OEM hammer spring/barrel/valve.

 

[jps2486]

Lots of theories and conjecture here. One test is worth a thousand expert opinions. I suggest tests be performed using weighted, sorted pellets. Weight variation should be no more than plus or minus 0.1 grain. Pellets that I've weighed can have extreme outliers of up to plus or minus 0.5 gr or more, so if you are shooting most of your shots using pellets at one end of the weight spectrum, then an odd ball at the other, you'll get a flier for sure. Further, pellets should be carefully inspected visually to weed out those with deformed skirts, dents and weird looking differences in the cavity. Don't forget, pellets are very subject to wind and a little puff of wind between you and the target will throw them off. Then there's head size.

 

[Franklink]

Lots of theories and conjecture here. One test is worth a thousand expert opinions. I suggest tests be performed using weighted, sorted pellets. Weight variation should be no more than plus or minus 0.1 grain. Pellets that I've weighed can have extreme outliers of up to plus or minus 0.5 gr or more, so if you are shooting most of your shots using pellets at one end of the weight spectrum, then an odd ball at the other, you'll get a flier for sure. Further, pellets should be carefully inspected visually to weed out those with deformed skirts, dents and weird looking differences in the cavity. Don't forget, pellets are very subject to wind and a little puff of wind between you and the target will throw them off. Then there's head size.

The last five cards that average 231 were shot with unsorted pellets. The previous 4 years worth of cards averaging 205-220 were shot with unsorted pellets, except for one sorting experiment. Sorting those couple of tins in that experiment produced slightly better results, but did not eliminate the unexplained flyers. If sorting was the answer, sorted pellets would not produce flyers.

Sorting is a bandaid with much better results in the psychological/confidence department than the accuracy department.

I compete (mostly field target) and don't sort pellets for competitions. I win my share of matches, always using unsorted projectiles. I also shoot probably 3-5 100 yard EBR cards a week. Granted field target doesn't require benchrest accuracy, but 100 yard benchrest accuracy is not 50 yard benchrest accuracy.

When a gun/tune/barrel is producing flyers with MRDs @ 100 yards, sorting will not eliminate them.

 

[thomasair]

I have a cat that is able to sniff out bad pellets. He is amazing.

 

[Franklink]

I have a cat that is able to sniff out bad pellets. He is amazing.

You should start selling kittens from that bad-pellet sniffing cat. Maybe we could find a tom with the same genetic abnormality and do some selective breeding to really exploit this trait.

Selling bad-pellet sniffing cats could prove to be more profitable than custom airguns.

It'd be all the rage, all the top shooters would have their pellet sniffing cat sitting on the bench with them at big events, offering each pellet up to the official sniffer extraordinaire for the furry yay or nay before sending it down range.

 

[thomasair]

He's always at my side

 

[SAZ]

If it works for Mike, I'll give it a try.....

 

[jps2486]

Sorting is a bandaid with much better results in the psychological/confidence department than the accuracy department.

I compete (mostly field target) and don't sort pellets for competitions. I win my share of matches, always using unsorted projectiles. I also shoot probably 3-5 100 yard EBR cards a week. Granted field target doesn't require benchrest accuracy, but 100 yard benchrest accuracy is not 50 yard benchrest accuracy.

I tend to agee that sorting will not completely eliminate the problem, but it will likely help your scores. Pellet hole placement from a 9 to an 8 frequently can only be measured with a scoring plug because the difference can be so slight. Just a difference in 2 or 3 points can mean winning or losing a match.