S400 not liking Qtec Mod

[MrCobraman]

Hi Guys

My mate has a S400 that recently got fitted with an AA Q-Tec moderator. All seemed fine, but when I used it the other day, pellets were getting flung high left. Took mod off the gun & sights back on the money. Put the mod on my S410 & it shoots straight. Back to the S400 & pellets off target again. S400 is grouping nicely, just not on target. Rotating the mod seems to change the severity of inaccuracy slightly. I've read a few posts on 'tinernet that say Q-Tec can be iffy, but weird that it works on one gun but not the other.

Any thoughts?

[MrCobraman]

Okay, mate has admitted to dropping rifle off the boot of his car! Still strange that gun & mod seem fine independently, but can't get on together...

[Brooksy]

By dropping it maybe he put a slight bend in the barrel, is it the same barrel as the S410 with the lathed end?
I would imagine that the thinner metal may well be bent causing clipping.

[MrCobraman]

Yup, barrel is same with lathed end. I think you may well be right! New barrel?

[Brooksy]

Remove it, place it on a granite worktop and roll it around, if you can, measure deflection with feelers gauges even if you use the whole set at once, you can possibly get it straightened. If you mark where the bend is. Dave at Staffordshire Custom Rifles or any good engineer will be able to sort it.

[32:1]

Today I tried three silencers on my s400
Zeroed at 35 without anything which gave best grouping by the way, qtec was 2inches low and 1/4" right, old AA was 1.5 inches low and inline, hw was 1,1/4 low to the left 1/4 inch

Old AA grouped best with 6 pellets in cloverleaf of 8mm, other two were 12mm but bare barrel delivered a virtual hole of 6mm

Chris

[Brooksy]

All silencers alter the airflow, that's why HFT shooters use air strippers and adjust them for the best consistency. My advice would be to choose the quietest silencer and zero the gun. Take the silencer off and refit it, if the zero holds you've cracked it. However a slip on silencer will need to be marked for consistent alignment or your POI will change with the smallest rotation.

[MrCobraman]

Okay so the problem was....

The barrel ring (bit that holds barrel above the air chamber & looks like a figure eight) had got knocked. Once recentred the gun was firing as expected!