AA s510 Sporter metric or imperial grubs? Also, barrel centering question.

[stewie]

Hello all,

Shooting at a varmint the other night, the shot was way off--3 inches to the right at 25 yards. Took a look at the barrel in the light of day and noticed that, from above, it wasn't aligned perfectly over the air/reservoir tube below. (I suspect that a family member may have propped the gun against the wall while doing some housecleaning, and let drop against a corner.) In any case, I was going to loosen up the front clamp, but want to be sure that I'm using the right size hex wrench on the grubs, so: does Air Arms us metric or imperial? 

Also, any tips on getting the barrel/shroud lined up? Eyeballing it from above seems awfully crude. Thanks

 

[hawkeye69]

If it was made in the UK, undoubtedly metric.

 

[Tvanpool]

I was going to loosen up the front clamp, but want to be sure that I'm using the right size hex wrench on the grubs, so: does Air Arms us metric or imperial?

If by "clamp" you mean the barrel band, the grub screws take a 2 mm allen wrench (a 5/64th allen may work bettter). The grub screws are easy to round out with a poor fitting wrench so find one that fits well. Loosen both screws and let the barrel find its own center and retorque the screws. Now sight in with the barrel in its new unstressed position.

 

[stewie]

Okay, thanks Hawkeye and Tvanpool, much appreciated. Those hex heads in small sizes do round out very easily. Do they make a substitute grub with a different head? If so, I'll replace them.