Price out a Helicoil kit and be sitting when you see the price!
My experiences with Helicoil installs at shops (Car and bike, not gun) have been that the price of the entire kit is very near the price of the job, if you can swing a Jobbers Price on the kit, anyways.
I deal with Helicoils almost daily. Inch sizes though. I don't get much call for Metric in my work, so we don't stock 'em.
There are a couple sizes in the 2mm range that may be what you have. Can you measure the screws? Need to know the diameter for sure, as well as the thread pitch. Gun business is strange. Sometimes they use standard pitches, sometimes not. You really need a thread pitch gauge or a set of similar sized screws to compare to, to see what the thread pitch is for sure.
If you can source a Helicoil tap and the coils themselves, drilling the correct size is easy as is tapping out the hole. An install tool can be faked, if you cannot find someone with one to borrow. A piece of wire under the bore size, and a needle file, to build a tool that will do what you need. Jeezly expensive tools for a single use. Check Ebay, though. A quick look there shows few places selling the stuff you probably need. Mostly in the UK, but if you need the stuff. May be worth contacting one of the sellers to see if you can source just what you need. Looks like about 30 dollars plus postage gets you an M2.5 kit with 20 coils. You may never use them again, but ....
Stuff to know when ordering. The lengths are usually a factor of the diameter. 1/2, 1, 1.5, 2, etc times the diameter of the thread it fits.
Your best bet is to get a free running insert, rather than a locking one. The free running inserts are easier to install, as well as you are gonna use threadlocker anyways, right?
If all goes well, you get full strength on 2 to 3 turns of engagement of the screw thread. If you drop a coil in that takes up the full length of the hole, though, you won't make it stronger, but you may bypass part of the hole that is oversize and weaker...in theory, anyway.
May be worth checking with bike shops to see if they have a kit. Seems that size is about right for some hardware on some of the high end gear etc., so they may be willing to patch those up. If so, then talk price with them maybe.
Hope that is of use.
Cheers
Trev
