FWB Sport pivot adjustment

[Michigander]

After getting my FWB Sport back I of course wanted to see how it would perform. I mounted a scope and took it out to sight it in. After maybe 30 shots, I noticed that the pivot was loose. I took off the stock and found the M4 flat head locking screw had worked its way loose. This had never happened with the rifle as received from the factory. I can only assume that the factory torque had not been applied to the locking screw when the rifle was worked on. In any case, I adjusted the pivot and torqued the locking screw by feel to what seemed like the most I should apply to that small screw. But after maybe 60 more shots the pivot was loose again. Removing the stock confirmed that the locking screw had worked loose, although the pivot bolt was still in the position I had left it.

I went online to find the max torque for that type of fastener, and without knowing the exact grade figured it to be between 30 and 40 lb-in. This time after adjusting the pivot I applied Industrial Loctite 222 to the threads and torqued the locking screw to 30 lb-in. I do expect it to hold this time.

I am posting this mostly to let people know that the locking screw has a tendency to vibrate loose, and that it seems to be capable of handling 30 lb-in of torque. This is definitely a case where a good torque wrench is almost essential.

 

[thumper]

Sounds about like the old 124s. They were always loose and made the POI shift all over the place. 

Maybe you fixed it this time. 

 

[DonC]

Where and what is a "locking screw"?

Thanks

 

[Michigander]

The FWB Sport pivot bolt is split on the end like an expanding mandrel, with a tapered screw used to expand the end and lock the pivot bolt in place. It might be an arrangement that is unique to this rifle.

 

[Michigander]

I did hear back from FWB on the recommended torque for the pivot locking screw. They say there is no "torque diagram" for the Sport, but that "3.4 Nm (30 lb-in) is not a problem". After a couple hundred shots my gun's pivot adjustment is still holding at the 30 lb-in tightening torque on the locking screw. Since it only took 20 shots or so to start loosening when hand tightened to around 15 lb-in, I do expect the pivot to stay in adjustment this time.

 

[wijib]

Thanks for the heads-up. I haven't been shooting mine much due tot he weather. I will keep and eye on it . Haven't heard form anyone else that this is a problem but hopefully you've remedied the issue for good.

Bill

 

[GoldenStateAIRGUNer]

After getting my FWB Sport back I of course wanted to see how it would perform. I mounted a scope and took it out to sight it in. After maybe 30 shots, I noticed that the pivot was loose. I took off the stock and found the M4 flat head locking screw had worked its way loose. This had never happened with the rifle as received from the factory. I can only assume that the factory torque had not been applied to the locking screw when the rifle was worked on. In any case, I adjusted the pivot and torqued the locking screw by feel to what seemed like the most I should apply to that small screw. But after maybe 60 more shots the pivot was loose again. Removing the stock confirmed that the locking screw had worked loose, although the pivot bolt was still in the position I had left it.

I went online to find the max torque for that type of fastener, and without knowing the exact grade figured it to be between 30 and 40 lb-in. This time after adjusting the pivot I applied Industrial Loctite 222 to the threads and torqued the locking screw to 30 lb-in. I do expect it to hold this time.

I am posting this mostly to let people know that the locking screw has a tendency to vibrate loose, and that it seems to be capable of handling 30 lb-in of torque. This is definitely a case where a good torque wrench is almost essential.

If it doesn't hold try Vibra-Tite VC-3 instead. I've had better luck with it. I think 222 (purple I think ?) is not going to work.

 

[Michigander]

To be clear, the pivot did not loosen until the gun had been worked on to address a warranty issue. The USA warranty service apparently did not tighten the locking screw enough, and it loosened. Loctite 222 is a very mild thread locking compound that we used to use on machine assemblies where I worked. If the pivot loosens again, I would definitely go to a stronger thread locking compound because I don't want to go beyond 30 lb-in on that rather small screw. Vibra-Tite sounds like a good option.

 

[pmg]

I’m curious as to what was wrong with the sport to trigger warranty work? I’ve read about another gentleman who has had fail to cock issues. I’ve not had any other than poi issues from day to day. 

 

[Michigander]

In my case the gun would not fire. I believe the middle lever was not releasing the upper latch lever when the trigger was pulled. Maybe the upper sear surfaces needed to be polished, or the middle lever was binding somehow, I don't know. I didn't want to void the warranty, so I didn't take it apart. I was told the problem had never been seen before, and the gun has been working fine since the repair.

I don't bad mouth a company if they are willing to stand behind their product, and FWB certainly did. The gun was serviced at Pilkington, and the trigger assembly sent back to Germany for inspection and repair/replacement. Pilkington is great to work with. I had them service an LP5 for a broken valve stem, and it only cost me $150 to get a $1500 pistol back in service. Both times the guns came back working and looking like new. You can't complain about that.