Lgu 22 piston

[Alan's]

Hi has any one converted one of these to 22 mm piston and will it make 11 flb with the 88 mm stroke ?

[TonyL]

I'm not sure if anyone has done this particular conversion to the LGU. If anyone has, to my knowledge, the most likely candidate would be NickG. Hopefully Nick and Shed Tuner will be along to further advise. And, yes from everything I've seen relating to the reduced bore rifles, that stroke length should be sufficient.

[hmangphilly]

Plenty of 22mm lgu s around .

If you're converting , you're not tied to 88mm stroke

[NickG]

I have done them to 22 and 21 mm, they will both make power at the standard stroke, if & that's a big "IF" the barrel lead in / breech area has been attended to , but as Phil rightly says you don't have to stick to the standard stroke.

[Alan's]

OK thanks I am having trouble getting it to more than 10 flb with jsb 8.44 witch is fine and shoots nice with a tx mk3 spring witch I through may be down to stroke length as tx is 98mm, I've read in some old threads about this breach lead in is that a great help. It's 177 and skirtless piston, are yours full pistons Nick

[NickG]

OK thanks I am having trouble getting it to more than 10 flb with jsb 8.44 witch is fine and shoots nice with a tx mk3 spring witch I through may be down to stroke length as tx is 98mm, I've read in some old threads about this breach lead in is that a great help. It's 177 and skirtless piston, are yours full pistons Nick

Yes the 22 mm ones I did were full pistons. Check your pellet lead in . Can make a full fpe ( depending on the tune) when done properly, also try other pellet brands .

[Alan's]

Thanks again now I've put a titan tx mk3 spring in now it's doing 10.10 with jsb 10.75 with superdome still shoots well and been reading more about pelets jsb move a. Lot easier than others plus Tony's blog on pellet s and tp s and Peak pressure so jsb are moveing to soon and rws getting peak pressure as thay hold air back to get there so I'll keep tinkering as jsb shoot best plus I will chack pellet lead in

[hmangphilly]

Thanks again now I've put a titan tx mk3 spring in now it's doing 10.10 with jsb 10.75 with superdome still shoots well and been reading more about pelets jsb move a. Lot easier than others plus Tony's blog on pellet s and tp s and Peak pressure so jsb are moveing to soon and rws getting peak pressure as thay hold air back to get there so I'll keep tinkering as jsb shoot best plus I will chack pellet lead in

In one gun , we lost 80fps with the wrong leade .
Have a chat with Nick

what size is your Tp ?
what weight the piston assy ?

[Alan's]

Hi tp 3.5 mm piston 150.5 grams 88 mm stroke checked again after a morning at club now it doing 759ft with SD 757ft.jsb 761ft airarms 754 ft with super field so seem to have settled in all them pellets fit in with out much force . I'll have to find out more about the leed in .I am happy with any where between 10 11 flb on tp size Jim Taylor. Says it should not exceed 60% of length so at 5.5 that's 3.3 mm but that may be for standard set up ?

[NickG]

Hi tp 3.5 mm piston 150.5 grams 88 mm stroke checked again after a morning at club now it doing 759ft with SD 757ft.jsb 761ft airarms 754 ft with super field so seem to have settled in all them pellets fit in with out much force . I'll have to find out more about the leed in .I am happy with any where between 10 11 flb on tp size Jim Taylor. Says it should not exceed 60% of length so at 5.5 that's 3.3 mm but that may be for standard set up ?

You should be making power easily at that stroke , my 22mm for the hw 97 makes power easily at 85 mm stroke, as a check for your barrel lead in , flare the skirt of a pellet by pushing one on top of another then load it , and seat it flush using something flat, then see what power you get , bet it goes up.

[Alan's]

Hi again done that it goes down sames as nipping the skirt or sizing anyway it's OK now as it is as I don't want to put more preload in as the idea was to make it cock easier like the tx but there's a lot of differences between them and thats why I wanted to use a tx spring anyway thanks

[Shed tuner]

Hi again done that it goes down sames as nipping the skirt or sizing anyway it's OK now as it is as I don't want to put more preload in as the idea was to make it cock easier like the tx but there's a lot of differences between them and thats why I wanted to use a tx spring anyway thanks

did you try it with the JSBs, not the superdomes...

[Alan's]

Hi yes i did jsd i must admit that are a loose fit in the breach I've also done it with cheap BSA 7.56 peliits the tight fit can go20 to 30 ft faster than the looser fit one so it must be the loose fit of the jsb in the breach

[NickG]

Or the lost volume in the huge chamfer, that's normally what they have as a lead in.