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Hunter2011 · New Member

If its not the scope.
What can you do to stop this from happening?
I've got a FX Axor in .20. The rifle really shoots good groups at 30 meters. But just leave it alone for a week, shoot again, then you must re-adjust your scope for that little it shoots off the mark. I always only shoot in the rifles sweet spot.
Where can I look for possible problems?

mod90 · Veteran Member

I could be wrong, but this scenario doesn't sound like the rifle is at fault. I would also say to check the crown for burrs, but you said the 30yd shots were producing good groupings. Unless you're leaking air badly on the shot cycle I don't see why this should occur. How sure are you it's not the scope? It's possible according to the way it's stored and if there are a lot of heavy vibrations nearby or if it gets knocked hard while in storage it could change the POI. I'd try the scope on another rifle just to be certain.

Hunter2011 · New Member

I agree I can't completely rule out possible scope problems. I've got a Leapers 3-12X44 on her currently. I did take my Leupold scope from my .22LR to test it but I got basically the same results. I don't get POI shifts on my .22LR so I just assumed the problem can't be my scope. The rifle is handled as if I'm carying eggs. Its silencer is screwd on the barrel via a plastic adapter, very breakable so I really handle this rifle with care. It never gets knocked.
I think I must try it without a silencer, just a pity I won't be able to do it at home, its loud.

donwalk · Veteran Member

does it (the POI) drop? if it does, i would look for an air leak somewhere.

do you have a pressure guage? check the pressure and check it again a few days later.

if you have a 'scattered' POI, look for something that has loosened: scope mounts, barrel set screws, loose stock screws...

Hunter2011 · New Member

The rifle was recently serviced and is shooting a very constant 850 fps measured on a Combro Chrono. POI is not scattered, ussually POI can be fine for three months, then just suddenly its out, does not matter, sometimes it shoots high, sometimes low and left. Its never constant. There must be something wrong. But where can I start to sort out the possible problems one by one?

Dukemeister · Member

Barrel bands, barrel floating, air cylinder clocking, etc could be affecting POI.

SMP · Silver Status Member

To me this sounds like a classic case of stock shifting. Humidity changes causes the stock to move, grow, shrink and that changes the pressure point loads.

On a gun as subtle as an FX you would be able to see the effects. Most are not accurate enough to see the results.

The fix is to have the tension bolts pillar bedded.

Hunter2011 · New Member

SMP · Silver Status Member

You can get a ready assembled kit from Brownell's and several other places

Google "pillar Bedding" there are hundreds of links and you tube videos

There are also a few places in the US that do nothing but pillar bedding and they are very very good at it.

Hunter2011 · New Member

I'm in South Africa so a trip to the US is out Smile

I will start googling. Thanks

SMP · Silver Status Member

Whoah

Okay here is the basic idea behind Pillar Bedding

The wood around the tension bolts is drilled out to suitable size to install aluminum tubes that are epoxied into position with their height set such that when the action is bolted in it is held by only the pillars and the remainder floats above the stock by a millimeter or so

One step farther is glass bedding the area between the pillars with low shrinking fiberglass resin so that the action area is completely cradled but the entire forend is unable to exert any pressure points

Here is picture of one that's very nicely done