POI shift from session to session FX Impact stx vs RAW

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mubhaur

mubhaur

Member
Nov 8, 2015
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Karachi, Pakistan
I have noticed that my fx Impact mk2 is very accurate but it holds it perfect zero for a certain session. In the next session after a couple of days I have to adjust the scope 3 to for clicks in the desired direction. 

On the other hand my RAW has been holding POI perfectly session after session and each day.

I dont need to adjust the POI in RAW over a very long period. 

My assumption is that it's the matter of solid free float barrel vs pellet liner held with screw and with support of O rings.

Weather conditions affect the O rings and the POI is affected a bit.

I am not bashing any brand rather it's just my finding. 

Anyone else witnessed this phenomenon?

Regards, 

Umair Bhaur 
 
Looks like as RAW has very stiff free float barrel covered with carbon fiber tube, there is little chance of coming any change in barrel position. Also it is held with three big grub screws.

On the other hand stx liner is supported by O rings and only one screw holds the barrel and even the outer cover of barrel is also held by O rings, the temperature changes and any other changes affect the POI quickly. 

But once adjusted again, it shoots great again. 

Regards, 

Umair Bhaur 
 
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I had fx Royal 400 .22 and Royal 500 in .25 in the past and never faced POI shift issue.

Looks like the solid ST barrel was more sturdy.

Regards, 

Umair Bhaur
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Yep, as I type this, I'm sitting on the deck waiting for a squirrel attack on our bird feeder, with a Royale 400 in my lap. It's one of my favorite rifles, simple, reliable, accurate, never needs cleaning. 
 
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FX walks the walk in competition, so if clicking the scope turrets now and then is to difficult for you than stick with what works for you. IMO RAW makes a great gun to lay on a bench but isn't really most hunters choice.
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Yes in competition is where a lot of range queens shine, they can be catered to with various sundries. In the field not so much, if it can’t handle normal field conditions and maintain POI from session to session where’s the fun? And how can turning a turret be considered difficult😀? Though I do confess to rechecking zero regardless before going after critters. 
 
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FX walks the walk in competition, so if clicking the scope turrets now and then is to difficult for you than stick with what works for you. IMO RAW makes a great gun to lay on a bench but isn't really most hunters choice.
Click to expand...

Yes in competition is where a lot of range queens shine, they can be catered to with various sundries. In the field not so much, if it can’t handle normal field conditions and maintain POI from session to session where’s the fun? And how can turning a turret be considered difficult
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? Though I do confess to rechecking zero regardless before going after critters.
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I also recheck the zero often. My findings are based on rechecking of POI.

Regards, 

Umair Bhaur 
 
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While I haven't tried it yet, the use of harder 90 durometer o-ring inside of the barell support blocks should eliminate a lot of the barrel shift from storage. Currently in hey are standard 70 durometer o-rings and they are soft and squishy, so as the barrel sits with some tension on it the o-rings shift a little.

I have also been looking at placing a bushing on the barrel tube up under the front picatinny rail and drilling and tapping the rail to place 3 set screws on it. This would lock the middle of the barrel in place, but without changing the hardness of the o-rings at the breech end it may still allow some shift. It may also effect accuracy due to harmonics. If this works, it is the simplest way to solidly affix the barrel and there is plenty of metal to drill and tap set screws in. The nylon bushing band would be about 30mm o.d. with a 14mm i.d. and be wide enough to sit against the barrel support block but not come into contact with the barrel shroud.
 
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While I haven't tried it yet, the use of harder 90 durometer o-ring inside of the barell support blocks should eliminate a lot of the barrel shift from storage. Currently in hey are standard 70 durometer o-rings and they are soft and squishy, so as the barrel sits with some tension on it the o-rings shift a little.

I have also been looking at placing a bushing on the barrel tube up under the front picatinny rail and drilling and tapping the rail to place 3 set screws on it. This would lock the middle of the barrel in place, but without changing the hardness of the o-rings at the breech end it may still allow some shift. It may also effect accuracy due to harmonics. If this works, it is the simplest way to solidly affix the barrel and there is plenty of metal to drill and tap set screws in. The nylon bushing band would be about 30mm o.d. with a 14mm i.d. and be wide enough to sit against the barrel support block but not come into contact with the barrel shroud.
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I am thinking on the same lines.

Regards, 

Umair Bhaur 
 
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While I haven't tried it yet, the use of harder 90 durometer o-ring inside of the barell support blocks should eliminate a lot of the barrel shift from storage. Currently in hey are standard 70 durometer o-rings and they are soft and squishy, so as the barrel sits with some tension on it the o-rings shift a little.

I have also been looking at placing a bushing on the barrel tube up under the front picatinny rail and drilling and tapping the rail to place 3 set screws on it. This would lock the middle of the barrel in place, but without changing the hardness of the o-rings at the breech end it may still allow some shift. It may also effect accuracy due to harmonics. If this works, it is the simplest way to solidly affix the barrel and there is plenty of metal to drill and tap set screws in. The nylon bushing band would be about 30mm o.d. with a 14mm i.d. and be wide enough to sit against the barrel support block but not come into contact with the barrel shroud.
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Very interesting.If you go ahead with this little project please start a thread on it.
 
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Personally I dont experience a lot of issues with any of my fx rifles (Boss, Bobcat or Impact nor have I heard complaints from experienced shooters in the field like BobO the boys in S Africa and lots of other FX owners I know and shoot with. Funny thing The only gun has given troubles is an Edgun I own, probably because I modified it with a Huma reg although Huma says could be a defect from the manufacturing of the gun who knows? Any way I Absolutely love my FX rifles and their extreme accuracy on the bench and in the field.
 
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This issue is common for most of the FX models, not just the impact. There are several threads on this issue in the archives. I firmly believe the issue is the design of the single screw barrel mount design. It has nothing to do with the shroud, "O" rings or the other BS that has been spouted here. These guns are very accurate, but anything you do with the barrel from removal, reinstall to simply picking up the gun by the shroud will upset the zero. I am going to try a shroud support using the bottle on my Crown. I hope to make it better. I will get back to the forum after I complete the brace.
 
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