FX FX liner lock nut (jam nut) sanity check -- how tight?

[stovepipe]

I know the answer to the question "how tight should my jam nut be" is going to depend on liner length, caliber, fpe at the muzzle, whether the rifle is using o-rings as spacers between the liner and the barrel housing or a carbon fiber spacer instead. There are probably a lot of other things to take into consideration that I'm not even thinking of. And I know that a lot of the answers are going to be given in terms of how many turns after hand tight rather than torque specs -- either one is fine with me. I just need a sanity check.

I've got an fx maverick 30 cal sniper with a 1:18 twist liner and a carbon fiber spacer between the liner and the barrel housing. I'm shooting nsa 54.5 grain slugs at about 950 fps, but might go to 980 fps. Either way that's in the 109 fpe to 116 fpe range. The liner is trying to spin the slug to the right, but if the jam nut is too loose, then the liner will slip (spin) to the left. I want the jam nut to be tight enough to prevent the liner from slipping, but I don't want to bend my liner. I can't really tell if the liner is slipping or not and there doesn't seem to be any way to know for sure.

Currently I'm tightening my jam nut 1/16th of a turn after fully hand tightening, but I'm wondering if that's really enough -- is 1/8th of a turn OK without bending the liner?

The FX motto "not too tight -- not too loose" causes irreversible insanity.

stovepipe

 

[bigHUN]

You're looking for one of these....

FX Airguns Liner Lock Removal Tool

FX Airguns Liner Lock Removal Tool Easily remove and install your FX STX Barrel liner lock with this tool. Insert this tool into any tool that accepts 1/4" drive to quickly remove the liner lock from your STX barrel. Only for .177cal through .30cal. The .35cal liner lock uses a different style...

www.capefearairguns.com

Mike

business is growing, I was just wondering when will day come somebody start making money on these
I made mine from a spare 10mm socket wrench and a dremel

 

[Revoman]

"business is growing, I was just wondering when will day come somebody start making money on these"
Yes, they have been producing these for quite a while though, not new.
Your home-made looks great!

Mike

 

[bigHUN]

I always try to make it myself first, buying new is a last

 

[Ta-Ta Toothie]

26in/lbs works for me on my .22 600mm. Comes out at a 1/4" turn.

 

[hotspark]

You are back to exactly what I'm trying to avoid -- the FX motto "not too tight -- not too loose". Now tell me exactly which model of screwdriver I should use to guarantee that I'm not too tight to bend my liner and I'm not too loose to allow my liner to slip left as it tries to put a right-hand spin on a 54.5 grain slug going 980 feet per second.

stovepipe

That's smokin'! I've got .30 cal 54.5s @ 905 fps
700mm liner in a maverick. Tell me your tune, I'm curious.
Oh I just go snug +. I figure since it's all held in with a little set screw I don't want to pull it out.
If I cared to know the torque or in this case guess the torque since it's not published, I would torque it with a torque wrench and repeatedly check to see if the torque value changed(loosened). If not you could then try going tighter or looser until you get your most consistent groups and keep checking torque to see if it changes. Once you settle on what's working best on your rig,keep doing it. These fx guns seem particular and doing the same thing on the same model/same specs may or may not yield the same results.

 

[bigHUN]

Consistency is a key.
I am removing my liner at least once a week for cleaning but I remember a time when I was removing every second day...

 

[stovepipe]

That's smokin'! I've got .30 cal 54.5s @ 905 fps
700mm liner in a maverick. Tell me your tune, I'm curious.
Oh I just go snug +. I figure since it's all held in with a little set screw I don't want to pull it out.
If I cared to know the torque or in this case guess the torque since it's not published, I would torque it with a torque wrench and repeatedly check to see if the torque value changed(loosened). If not you could then try going tighter or looser until you get your most consistent groups and keep checking torque to see if it changes. Once you settle on what's working best on your rig,keep doing it. These fx guns seem particular and doing the same thing on the same model/same specs may or may not yield the same results.

Because I was terrified of bending or warping my liner, I was only tightening my jam nut 1/16th of a turn after hand tight. Other people were OK with this and I was too -- until today. A few days ago I started tuning my maverick sniper 30 cal for more power. Eventually I was slinging nsa 54.5 gr slugs at an average of 950 fps. But my extreme spread and standard deviation was really bad (sd was more than 9 fps). I changed breech o-ring and the others on the barrel, but it didn't help. I suspected that the 1/16th turn of the jam nut was not enough. I loosened the jam nut and hand tightened and then tightened 1/8th of a turn instead of just 1/16th of a turn. Just now put two magazines through the chrony and the extreme spread and sd is now acceptable (sd is now 4 fps). So for anyone with a maverick sniper 30 cal putting out over 100 fpe, I can say with some confidence that 1/16th of a turn of the jam nut is probably not going to "contain the situation". 1/8th of a turn seems to be working just fine. I wouldn't go higher than the 1/8th of a turn unless you knew for sure that you needed it. Keep in mind that I'm specifically talking 700mm 30 cal liner. 22 and 25 cal might have their own limitations and needs and longer liners might be more prone to bending than shorter liners. I don't know.

So my current tune is sending nsa 54.5 gr slugs at 950 fps average (using cheap chinese chrony) with a standard deviation of 4 fps (not great, but might get better after a couple more mags go through it). I haven't shot it at targets yet or even tried to sight it in, so I can't comment on accuracy -- maybe it will suck in that department. I only have 1 regulator and it is set to 161 bar using my non-standard belleville washer stack. My liner is the 700mm superior heavy (I HATE FX naming conventions -- useless) 1:18 twist liner from trenier outdoors. I'm using the huma pin probe and the huma tuning spring, both from trenier outdoors. I have a 13 gram hammer weight. I have the fx maverick quick tune micrometer for adjusting the hammer spring preload -- currently set at 7.14mm. I have a donnyfl ronin on my maverick. I also have the carbon fiber spacer between the liner and the barrel housing, marked as fx and bought from trenier outdoors. This tune seems to be pretty efficient for the power I'm getting. Getting 2 mags (26 rounds) and still having 185-189 bar in the tank left. The reason I chose to have only one reg was strickly because the plenum refresh rate sucked with two regulators. I didn't care that I'd have a huge plenum (160cc now ?). I don't really know if the monster pleunum helps in the power department or not, but it doesn't hurt. I think I could easily up the average fps to 960 or faster, but I'll talk to my hunting buddy (who actually shoots this rifle the most) first.

Wow, I've been rambling on. And it's hot as hell in this little computer room over the garage. Time for a break.

stovepipe

 

[HogKiller]

FX should publish this information.

FX doesn't have a clue what the torques specs are and if they did the assembly people most certainly don't use them. Over the top sarcasm, probably but ..... I've got two Mavericks and both were hit and miss until I fixed them. Still not getting rid of them.

 

[hotspark]

FX doesn't have a clue what the torques specs are and if they did the assembly people most certainly don't use them. Over the top sarcasm, probably but ..... I've got two Mavericks and both were hit and miss until I fixed them. Still not getting rid of them.

I seem to find something loose or amiss every time I take my Maverick out. Shoots great once everything is back in order.

 

[Ta-Ta Toothie]

It's a good thing they don't build aircraft...

 

[stovepipe]

FX doesn't have a clue what the torques specs are and if they did the assembly people most certainly don't use them. Over the top sarcasm, probably but ..... I've got two Mavericks and both were hit and miss until I fixed them. Still not getting rid of them.

FX sarcasm gladly accepted 24/7. I try to hide it, but with every word I write or speak about FX airguns, three years of naughty words are trying to find their way into the verbiage. How is it that I (an average guy) now knows more about FX regulators than FX does? I don't want to be smart -- I just want to shoot stuff!

stovepipe

 

[stovepipe]

I seem to find something loose or amiss every time I take my Maverick out. Shoots great once everything is back in order.

That's been my story for three years. I think I'm finally ready to start shootin'.

stovepipe

 

[hotspark]

That's been my story for three years. I think I'm finally ready to start shootin'.

stovepipe

I already know way more than I wanted to about fx mavericks. I'm sure there's more that I'll learn over time. I won't pass the problem child onto someone else so I'm sticking it out.

 

[Airgunmann]

My question were guns being built at fx USA maybe they knew there days were numbered?

 

[huntr]

I need one of those. Is that a custom part, or is there a common name for that bit?

stovepipe

FX Airguns Liner Lock Removal Tool

FX Airguns Liner Lock Removal Tool Easily remove and install your FX STX Barrel liner lock with this tool. Insert this tool into any tool that accepts 1/4" drive to quickly remove the liner lock from your STX barrel. Only for .177cal through .30cal. The .35cal liner lock uses a different style...

www.capefearairguns.com

I think if you go an ⅛-¼ past hand tight you're going to cause trouble.

 

[stovepipe]

That's smokin'! I've got .30 cal 54.5s @ 905 fps
700mm liner in a maverick. Tell me your tune, I'm curious.
Oh I just go snug +. I figure since it's all held in with a little set screw I don't want to pull it out.
If I cared to know the torque or in this case guess the torque since it's not published, I would torque it with a torque wrench and repeatedly check to see if the torque value changed(loosened). If not you could then try going tighter or looser until you get your most consistent groups and keep checking torque to see if it changes. Once you settle on what's working best on your rig,keep doing it. These fx guns seem particular and doing the same thing on the same model/same specs may or may not yield the same results.

Hotspark, there are a couple of things I forgot to mention about my tune(s). The huma pin probe sticks out a bit when the rifle is fully cocked which keeps me from easily putting in or removing a magazine. Some people sand down the pin probe, but I leave mine full length (and inconvenient) so it puts the 54.5 gr nsa slugs a bit more forward of the transfer port.

Also, I said I was slingin' the 54.5 gr nsa at 980 fps -- well not yet but I probably can with my current reg pressure of 161 bar. 980 fps would be the full 116 fpe advertised by fx for this rifle. The closer you get to that power, the more likely you are to bend the cocking rod and rod guide. The rod and guide are sucky by design. Last fall I cranked the reg up to 170 bar (easy enough to do when you only have one regulator) and was shooting the 54.5 gr nsa slugs at 1001 fps! That's over 120 fpe. It was great for about 100 rounds. Then the cocking rod and guide bent and I had to replace them. My point is that I think the mav can handle reg pressures up to 160 bar OK as long as your hammer is set to get below peak power from that pressure.

stovepipe

 

[hotspark]

Hotspark, there are a couple of things I forgot to mention about my tune(s). The huma pin probe sticks out a bit when the rifle is fully cocked which keeps me from easily putting in or removing a magazine. Some people sand down the pin probe, but I leave mine full length (and inconvenient) so it puts the 54.5 gr nsa slugs a bit more forward of the transfer port.

Also, I said I was slingin' the 54.5 gr nsa at 980 fps -- well not yet but I probably can with my current reg pressure of 161 bar. 980 fps would be the full 116 fpe advertised by fx for this rifle. The closer you get to that power, the more likely you are to bend the cocking rod and rod guide. The rod and guide are sucky by design. Last fall I cranked the reg up to 170 bar (easy enough to do when you only have one regulator) and was shooting the 54.5 gr nsa slugs at 1001 fps! That's over 120 fpe. It was great for about 100 rounds. Then the cocking rod and guide bent and I had to replace them. My point is that I think the mav can handle reg pressures up to 160 bar OK as long as your hammer is set to get below peak power from that pressure.

stovepipe

My second reg doesn't seem to want to go much over 135 bar, the adjustment screw is just above flush already. When I first got it back in March the regs wouldn't get over 100 bar so I sent it back. It has the fx slug power kit and the 1:22 twist 700mm liner. Like I said, averages 905 fps with nsa 54.5s. Hits hard and is as accurate as I am after a few settle in shots.

 

[stovepipe]

My second reg doesn't seem to want to go much over 135 bar, the adjustment screw is just above flush already. When I first got it back in March the regs wouldn't get over 100 bar so I sent it back. It has the fx slug power kit and the 1:22 twist 700mm liner. Like I said, averages 905 fps with nsa 54.5s. Hits hard and is as accurate as I am after a few settle in shots.

A stock fx mav sniper 30 cal should be able to have the 1st reg set to 170 bar and the 2nd reg set to 150 bar (unless it was intended to go to a country that only allows low-powered air rifles). Did you get the rifle used? Is there a warranty? Did you watch youtube vids to see how to set the regs to 170/150?

stovepipe

 

[hotspark]

A stock fx mav sniper 30 cal should be able to have the 1st reg set to 170 bar and the 2nd reg set to 150 bar (unless it was intended to go to a country that only allows low-powered air rifles). Did you get the rifle used? Is there a warranty? Did you watch youtube vids to see how to set the regs to 170/150?

stovepipe

It should still be under warranty. It already went in for regs when I first got it, took 6 weeks to get it back. Took so long that I bought a Taipan Veteran2 Tactical. Now that's a gun! The maverick is shooting good where it's at, when it shoots...might just get some huma regs down the road.

 

[stovepipe]

It should still be under warranty. It already went in for regs when I first got it, took 6 weeks to get it back. Took so long that I bought a Taipan Veteran2 Tactical. Now that's a gun! The maverick is shooting good where it's at, when it shoots...might just get some huma regs down the road.

The thing about the mav and regs and liners, etc. is that you really need to think about what you want it to do (if it's not already doing it) and research what it would take to make that happen. I'm talking about slugs vs pellets, light vs heavy, max range for accuracy, hunting (and what) vs target shooting, etc. Trying to pick bits and pieces of reliable info from youtube vids and forum posts can be a major pain in the ass -- there's always something they're not telling you. Sounds like your mav is shooting accurately and at 905 fps I expect your shot count per tank fill is pretty good. If you want more power from the mav, it can shoot at 109 fpe comfortably and it's easy to go with a single regulator setup. The only hard part of the single reg setup is that you might need to take out the reg and figure out a better belleville washer stack that is happy in the pressure range you plan to work in.

stovepipe