thank ye gents. i always enjoy working on these "kit" investarms guns. the only real work is knocking down the wood to meet the furniture and all it takes is a small rasp and LOTS of elbow grease ... and, there is no pressing requirement to take down any of the wood, other than for aesthetics. the fit of the parts is extraordinarily good, nothing special to do, they all just fit into place and no inlet work required at all. so, i highly recommend these "kits" and the savings is in the order of a good hundred buck$.
i pretty much use the LMF stain for this work and this is the first time i've used their american walnut flavor - wow, it's *perfect* for that deep olde tyme dark walnut look when it goes onto real walnut, with very little red in the hue. gonna use it on the beech wood of the DGW kit gun next. the other LMF stain colors i've used - lancaster maple, walnut, nut brown - all exhibit lots of red, which sometimes can be a bit overwhelming.
to me, there are 3 stages, or degrees of lock tuning. i'm gonna be preaching to the choir here for the most part, but this might be of help to a few folks ...
the first and most accessible tuning is to clean the entire lock inside and out, dry out, and spot oil the bearing surfaces, then set up a good flint in the cock jaws and set the proper angle. along with a proper flint, the frizzen's hardness factor is important for throwing good sparks, but that also requires the proper gun flint setting. the flint is adjusted so that at half cock, and with the frizzen down over the pan, the biting edge of the flint is almost touching the frizzen and barely misses the pan when down all the way. as to whether the flint should be bevel up or down only matters for whatever works best (that is, making the best sparks). all of this is a must-do, or all bets are off on ignition reliability.
the more invasive lock tuning means a total disassembly, which should leave a flat lock plate that *might* need to be levelled (hammering and/or filed) and polished to maybe 600 grit, in a progression of grits that might hafta start at 120 or 220, but at the least 320. all the touching/bearing sides of moving lock components also get polished up to 600 grit. all load bearing surfaces should get a very light, very careful fine stoning for polish only and not for removal of metal. after reassembly, all moving joined surfaces get quality oil lubed. so what does all of this accomplish? depends. if the lock moving part surfaces were really rough and gritty, the benefits of overall lock speed would be visibly noticed, but if the parts were reasonably smooth to begin with, probably at best a few extra milliseconds of cock fall speed, that's all. i've done all of this to siler and l&r locks and it can make an increase in both lock smoothness and speed. it should be noted that the investarms locks are not of "vintage" architecture and their plates have some welded components which will hamper any plate levelling. they also employ a coil mainspring instead of a leaf spring, which for me is just fine, and there's a plate that covers the tumbler and fly that needs to be removed, no big deal.
the major lock tuning means adjusting its mechanical geometry. this is a gunsmith's job, not for a hobbyist, because it means changing the angles and bearing surface areas of the tumbler notches for the positions of fire, half cock and full cock. the steel and hardening qualities of the tumbler, sear, fly, and bridle must be of superior quality to begin, and if not they need to be properly hardened after the modifications are accomplished.
anyhoo, weren't much needed to make this lock work well and shower sparks into the pan using a good "tom fuller" english flint of the proper size. this GPR is for my bud dave in tennessee. i think he's gonna be a happy camper and will make some meat with it next year.
