Drilling a Gamo Whisper for a scope stop

[Packman]

I have a Gamo Whisper .177 that I've had some scope issues with. The recoil is hard enough that the scope keeps walking back out of the dovetail grooves. I bought a scope base with a stop pin, but the reciever isn't drilled for a pin.

Can I safely drill the top of the reciever for the stop pin? It doesn't need to be super deep but I don't know what's under the dovetail area and I don't want to hit anything I shouldn't.

Thanks in advance.

 

[chicharrones]

I've dealt with that issue with an older Gamo Recon. Under the rear section of dovetail is the piston spring and under that will be the trigger and sear mechanism.

If you can drill shallow enough to not hit the spring, then you have to worry about keeping metal chips from the drilling process out of the gun's mechanicals. The "receiver" tube is very thin compared to a firearm receiver.

In a perfect world you should take the gun apart to drill the hole, but you need to figure out some sort of spring compressor to keep that powerful spring from getting loose while taking it apart and causing trouble.

Or, you can put a blob of grease on the drill bit and drill a little at a time, stopping to clean off metal chips that the grease catches and recoating the bit with another blob of grease. That method works fairly well, but it won't stop all metal from falling into the gun, plus the underside of the receiver tube will have a burr on it that the spring may or may not rub against.

However, it can work. Like I alluded to before, I've done the drill and grease method myself.

 

[Packman]

Updating for posterity:
I pulled the old scope off today. Turns out the reciever has an integral receptacle for a scope stop pin. I just couldn't see it with the old mount on there.

 

[chicharrones]

Updating for posterity:
I pulled the old scope off today. Turns out the reciever has an integral receptacle for a scope stop pin. I just couldn't see it with the old mount on there.

That is good news. Does one of the scope mounts have a set screw that can be lowered into that receiver hole? Using Loctite will keep that screw vertically in its threads once set.

 

[Packman]

That is good news. Does one of the scope mounts have a set screw that can be lowered into that receiver hole? Using Loctite will keep that screw vertically in its threads once set.

Yes, the new mount has a screw for the stop pin. I haven't had a chance to zero the new one but the mount feels much more solid.

 

[Chevota]

Fyi, imo, they can usually hold if you have good mounts and/or the gun is tuned, assuming the clamp screws are actually tight which some people don't do correctly. Like taking into account the friction of nasty chinese threads and no lube which may eat up most of the torque, so it feels and measures tight, but it's not actually tight.
Some good reasons to skip the lock pin are; a nice gun, like German, where you wouldn't want to use the stop pin b/c it'll booger up the hole, or when you want the mount somewhere other than where the hole is.
Oem mounts typically cannot hold w/o a stop of some sort, but the mounts listed below work great. They are also very cheap and look really nice. The two-piece are pretty grippy with the two large 5mm clamp screws. Optionally the one-piece is good if you like the look of it, but I drill/tap it to make it a 5 screw unit which obviously clamps to a whole new level but mainly I do it for looks.

My favorite two-piece is:
AGD; https://tinyurl.com/ybe75my5
PA; http://tinyurl.com/24rstho
My favorite one-piece is:
AGD; https://tinyurl.com/yc6alkaz
PA; http://tinyurl.com/pa6u23l