It seems every year, usually in the fall, I get about 5 customers that want me to zero in their new scope or rifle. I've always been surprised by this as I'd think people would "want" to shoot their guns but Oh well, I tell them 25 bucks, they provide the ammo, and I'll gladly shoot other peoples guns. One problem I see regularly is that they'll bring in some FMJ target ammo or whatever is cheap at the time. I tell them that they should be sighting it in with the hunting ammo they plan on using, to which they respond with "I'll adjust it more at the range when I go." Whatever, the customer is always right, and I enjoy shooting other peoples guns... so sure.
The issue is that with the cheap ammo, sometimes the groups are horrible. I try to do my best to center the "group" on the bullseye but sometimes it's hard to do and I'm not sure if that flyer is because I flinched and didn't realize it, or it's ammo related. This year, I got a lead sled, then modified it so I could make micro windage adjustments, and then decided to build a remote trigger to help eliminate the human element. That way I can be sure that the groups are as good as they can possibly be, plus... I've always wanted to make one!
I found an old brushcutter in the barn that I'd been holding onto for 15 years for some reason, so I stole the throttle cable and trigger from it, (then put it back into storage for probably another 15 years.) Then I got to work making the rest of it. It turned out pretty well, it works great, is able to be installed without tools, and has about a 5.5lb trigger pull, with an adjustable maximum 3/4" of throw.
Here it is installed on my Remington 700
In these two pics you can see the position before and after the trigger throw.