Impact M3 liner lock - why are Orings present ONLY in 177 and .22??

[TDK]

There is a different liner lock for each caliber (part 10 on the M3 barrel kit diagram https://fxairguns.com/wp-content/uploads/2021/04/F10373-pipkit-impact.pdf). The .177 and .22 versions have two orings inside (part 11 in diagram). The .25 and .30 do not.

I have a .22 and .30 M3, both using carbon liner sleeves. The .30 with no orings is more repeatable. When I tighten the liner lock down, the liner stays put where I have it indexed. Zero is very repeatable when pulling and reinstalling the liner, usually only one click on the scope if any. Last time I reinstalled it, it was dead on, no adjustment needed.

The .22 liner lock with orings wants to spin the liner when I tighten it down. This makes maintaining liner index point difficult. I installed one OEM liner oring in front of the carbon sleeve to add some rotational friction to the liner and this helps hold the liner in place. Overall, the .22 liner lock with orings seems to cause more headache and zero is less repeatable.

Anyone have ideas why this difference exists? I'll take metal on metal for centering and securing the liner end any day. If someone made an oring-free .22 lock I'd buy it in a second.

 

[trlrman]

Good it's not just me ! I think I will try a golf tee pushed into the liner next time and see if it helps ? 

The 22 i could snug the barrel grub screw and it helped the 177 no help.

 

[R0B]

I wouldn't think it would be too difficult to buy a .177 liner lock and drill it out to a suitable size for a .22. Do you know how tight the tolerance is for the .30 lock/barrel?

 

[TDK]

I wouldn't think it would be too difficult to buy a .177 liner lock and drill it out to a suitable size for a .22. Do you know how tight the tolerance is for the .30 lock/barrel?

You might be onto something there. I looked up the internal orings and difference is 1mm, so if you drilled out the .177 lock you'd be right at the depth of the oring grooves. The thing I would be concerned about, and haven't been able to identify, is the taper at the end of the hole in the liner lock. For the .25/.30 that don't have orings there has to be a taper there, I just can't tell exactly. The tolerance to the liner is close, but not friction tight or anything. Centering must be happening via the mystery taper in the end.

Seems like something that a machine shop could do fairly quickly and cleanly, but I'm not sure I'd want to tackle it with a hand drill or even drill press.