Rapid 12-250 blows out the Grub screw

[rsedwards1]

have a Rapid 12/250 the 4BA thread is stripped holding the exhaust valve .it blows out the Grub screw this only happens on firing and no leak otherwise.
I have a hele coil kit , but was told that a new block is the only answer any thoughts appreciated.

[Ca_Varminter]

I would re-tap the threads one size up..
I believe it would be a 4mm thread....
A couple of members have done this Fix!!
https://rapidforum.co.uk/forum/index.php?topic=4309.0

Good Luck,
Stuart

[angrybear]

have a Rapid 12/250 the 4BA thread is stripped holding the exhaust valve .it blows out the Grub screw this only happens on firing and no leak otherwise.
I have a hele coil kit , but was told that a new block is the only answer any thoughts appreciated.

Impact Airguns are Norfolk based (iirc), they re-tapped one for me a few years back for not a lot more than buying a decent quality set of Taps would have been, I'd give Chris a call.

[Squinty]

As already recommended re-tap a metric fine one size up.
Not that different to a fitting heli-coil and 3mm grub, isn't a lot of metal to work with.