The guys looking for the heavy 5.0mm Eunjins got me thinking and it was a bit slow in the morning, so I got to play a bit in the workshop. I also cannot get those Eunjins to group at all.
I made a "Pellet Reducer" to reduce 5.5mm pellet down to 5.1mm. More to proof a point than anything else. These are very basic and not intended for producing lots of pellets. For that one should consider a more efficient design.
See Album. https://www.airrifle.co.za/album.php?albumid=738
Below is an explanation of what is going on there.
Firstly, this is the tapered reamer I bought for reaming the barrel ports. I used this to ream the Pellet Reducer hole so that the exit is exactly 5.1mm. Because it is tapered it also gradually reduce the pellet to the correct size.
I assembled the reducer and the holder on my woodwork bench. Placed some bubble wrap below for a soft landing for the pellets.
By placing the pellet carefully in the reducer and then using the punch and hammer slowly tap the pellet through. When they come out the other side they look like this. The pellet sides (head and skirt) gets flattened a little to the correct size of 5.1mm.
Left to right
Standard 5.0mm, 13.7gr
Reduced 5.5mm, 16gr (before & After)
Reduced 5.5mm, 18gr (before & After)
For testing I did not change anything on the rifle or scope, only the pellets. The aiming point was always the center.
Then it was play time......
I shot a 10 shot string at 30m over the chrony with the Standard JSB Diabolo Exact, 5mm, 13.7gr.
See the excel file below and the target photo in the album, top left. Not bad and there was a bit of wind gusting around also.
Then I took the "reduced" 5.5mm AA Diabolo Field, 16gr's and shot them. I did not weigh them again. Shot 10 shots over the chrony.
See the excel file below and the target photo in the album, top second from left.
Then I took the "reduced" 5.5mm AA Diabolo Field, 18gr's and shot them. I did not weigh them again. Shot 10 shots over the chrony.
See the excel file below and the target photo in the album, top second from right.
I think the one pellet that went low was me.
Lastly I again shot a string with the Standard 5.0mm JSB's, top right.
All groupings are ten shots. I think the photo's and chrony string speak for themselves. If you want heavy 5mm pellets, lots of time etc then give it a go.
Finaly I also tried to reduce some JSB Exact Monsters. They did not work because the skirt became to long and thin. When you try to chamber them they get distorted.