FWB 124 Accuracy Problems

[Steve Cover]

Hi,
I need your opinion.

After 44 years of good service, I finally found that I could afford a full tune-up for my 1978 era FWB-124 air rifle.
Sometime during those 44years I radically modified the stock.
I trimmed it straight forward from the base of the trigger and replaced the trigger guard with a steel Neil Jones 660 Remington aftermarket trigger guard.
Naturally, I had to make major modifications to  the Jones unit for the 124.
I like the appearance much more now, and it didn't seem to affect the rifle's accuracy.

After receiving my rifle back from rebuild. the first couple of shots were obviously diesels.  (I was super unimpressed!) 
However, after the first few shots, it settled down and chronographs at about 800 FPS.

My problem is accuracy.  After its return I can't do any better than 1.5 - 2" off  a solid benchrest at ten yards.

I read somewhere that the FWB 124 is hard on scope sights because of its violent spring action.
So I removed the Bushnell scope that I bought with the gun and replaced it and the scope mounts. 
(Also installed carefully and torque set  by hand to as close to the same as possible.).
I have also removed the action from the stock and checked for any minor high spots that may have warped their way into the stock over the last near half century.
Also inspected the muzzle crown and the chamber for problems. (None found)
I examined the mounting bolts and reinstalled them with as close to the same torque as I could by hand.
The new trigger breaks cleanly at a reasonable weight (I haven't checked the pull weight yet)

Having explored everything I can think of, it still shoots patterns instead of groups.

Luckily I have no ego when it comes to shooting, so I also considered "operator error".
However, I shoot a lot off the bench and have several centerfire rifles that go into sub-MOA groups without the fliers.

Here is an example group:  The first two or three pellet holes touch each other at 10 yards. The next flies high right about a inch or more. 
The next shot will either go into the first or second group. (See why I suspect the shooter?).
Unfortunately, this  doesn't hold true for the whole group.  Pellets  open up to a somewhat rounded group as shooting goes on. 
The results of the average 10 shot group is 1.5"-2" pattern.  This is not typical of the pre tune-up accuracy.

So, what do you think?

Have I over looked something?
(tried a variety of pellets… no change)
Or have I developed a bad habit in my technique? 
I don't have this problem shooting my 1022 off the bench, so I don't believe I have a flinch.

Is it something as simple as shooting several hundred pellets and let the new modifications settle in?

All opinions and suggestions are greatly appreciated.

Steve

[Motorhead]

Sounding like EITHER barrels crown got damaged or ..... if lucky just a blown/ damaged breech o-ring.

Would start there ... do a q-tip test at crown and good visual check ... replace or at least flip over the o-ring.

let us know what ya find.

[cnjl3]

Scott has some good advise.
I have read that rebuilding an air gun will sometimes change the diet of your favorite air gun. You then have to start looking for the most accurate pellet. It didn't happen in my case. Before and after the rebuild my FWB124 likes JSB's and CPHP's almost equally. I have also read that the pellet that gives you the highest FPE will most likely be your most accurate pellet. Both the JSB 8.44gr and CPHP 7.9gr yield the highest FPE in my rifle.

[Sundog]

I think, as you said, the shooter is your best suspect. 

If it will hit the same hole two three time and then fly, I wouldn't suspect the rifle.  The scope, scope mounts, and pellets, maybe.  If the three screws and the pivot bolts are tight, the rifle should repeat. 

I wouldn't flip the o-ring.  I believe they are flat on one side and only can go in one-way.  I would examine it for nicks, but unless you are getting velocity variations or verticle POI wander, I wouldn't suspect it.

I would suggest you work on your artillery hold and practice with a good pellet.  Mine is (read as "I am") fairing about the same.  I haven't fired enough lately either.  And keep an eye on the scope.  It could be getting beat up.

Regards and good groups.

 

[Steve Cover]

Thanks guys.

I suspected operator error but wanted to see if there was anything that might affect accuracy, that I looked over.
I still haven't moved my shooting bench from my Silhouette range to our new property. (I can shoot here too).

When I do, I'll be back at working on technique.

Appreciate the advice.

Steve

[Motorhead]

Just an o-ring ... flips over just fine

[Mark 611]

breech seals are usually the problem with the 124's! their APITA if you don't get the fit correctly and your accuracy go's out the window!

[Calmark]

I think the breech seal is the main culprit.  On this particular rifle it needs to be seated just right for a good lock up. 

I had a similar experience nearly two years ago when I got my FWB 124 and rebuilt it.  Since I was the one who put it back together and installed the new piston and breech seal, I thought I must have done something wrong to get accuracy like yours.  I kept shooting it figuring it would break in.  After close to 500 shots it seemed to be getting better but some days were worse than others.  I'd finally get a 3/4" group of 5 shots at 20 yards only to have the next be 1.5-2", mostly with a vertical stringing.  Because it "wasn't accurate" in my eyes, I didn't shoot it much in favor of my other rifles.  I did bring it out here and there to try again and still had the same issues.

Fast forward another 6 months and I finally got it shooting like the FWB 124 is famed for.  It was like it was suddenly accurate out of the blue.  It took probably 500-700 shots, but incredibly my groups started to really tighten up.  I think it was because I was getting to be a better shooter, but I'm also convinced it was due to the new breech seal in large part.  I think it took all those shots to compress the breech seal to the right size because the vertical stringing disappeared and really tightened up my groups and I was getting them at 3/4" to 1/2" at 20 yards most of the time now.  Now that it was "accurate" I started to shoot it a lot more and it only got better.  This was all with the same junky 6 power non-AO scope too.  After upgrading to a Leapers 3-9x32 AO scope I found the "fabled" FWB 124 accuracy and the rifle is now capable of repeated 1/4" to 1/2" groups at 20 yards.   

So, I suggest really checking your breech seal and barrel lock up and just shooting the rifle for a 500 count tin or two until everything is broken in.  That should give you plenty of time as well to get to know the rifle again.  Good luck! 

[Steve Cover]

I think the breech seal is the main culprit.  On this particular rifle it needs to be seated just right for a good lock up. 

<<< SNIP >>>

So, I suggest really checking your breech seal and barrel lock up and just shooting the rifle for a 500 count tin or two until everything is broken in.  That should give you plenty of time as well to get to know the rifle again.  Good luck! 

Thanks,

I'll do just that.
I had not considered the breech seal at all.

I don't know if replacing the breech seal was part of the tune-up I had done.

Right now I would be very happy with a 1/4" five shot group at 10 yards.

Steve