Ballistic efficiency question

[Phil B]

If I swap a barrel in .22 for an identical length barrel in .177, on the same rifle, is there a known percentage that the power will be lower from the lower efficiency?

Sub 12 ft lbs, 250mm barrel, everything else is identical (Edgun Leshiy).

If it’s 11.5 in .22 and still kicks out over 10 in .177 I’ll be happy. Thanks in advance.

[RobF]

If I swap a barrel in .22 for an identical length barrel in .177, on the same rifle, is there a known percentage that the power will be lower from the lower efficiency?

Sub 12 ft lbs, 250mm barrel, everything else is identical (Edgun Leshiy).

If it’s 11.5 in .22 and still kicks out over 10 in .177 I’ll be happy. Thanks in advance.

No. There's many variables that come into play, for a start the performance of the pellet isn't linear across calibres and designs.

[angrybear]

.177 is the least efficient calibre which is why pcp shot count is always lower, it uses more air to match the performance of .22 in the same rifle,
so with no adjustment to the power you will have less performance but there is no way to tell what it will be.

[Phil B]

Thanks, I was hoping to get just a rule of thumb value but this is as expected really.

I can up the efficiency by adding a 350mm barrel to the .177 according to the chaps at BAR, but was wondering what happens without.

I’ll try it and update this afterwards for searchable info’s sake.

Thanks

[PhatMan]

Phil B,

Only one real way to find out !

I fitted a Wonky Donky 0.22" service kit (which was giving 11.2 ft.lb in a 0.22" HW99S) into my 0.177" HW99S.

It made a hair under 10 ft.lb - so an apparent loss of ca. 1 ft.lb.

However, this is comparing the spring performance in two (2) different examples of the HW99S, which are probably different internally in many ways.

So take the result with a large dollop of salt.

Have fun & a good weekend

Best regards

Russ