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How to, SMK 78 Free Strip & Tune Video

SMK QB/XS/TH 78 (79 is similar) FREE Stripdown Video

Just an note for any one who has trouble with the bolt probe locking up when you tighten the breech down. Some 78/79s have some pins that are a fraction too long. So the cure is just to shorten the two pins by half to one millimetre.
I have had three customers out of four thousand that have had trouble with cocking the gun after fitting our kit. In every case it has been that they have put the hammer at the back instead of the front. Make sure that you have put the hammer at the front and the rear spring guide and holder at the back. Another check is to look in the under slot where the trigger sear engages, you should not be able to see the hammer spring. The new 501 is similar so this would give you some idea of how it works. If the power is too high then you can cut half a coil or so off the hammer Spring. But make sure you are using a good chronograph and do not over do it as it can make a big difference. Click on the link below to watch the video on You tube.

I have just taken a 78 apart to tune and found that the fibre wad had jammed around the spring and piercer. I have put put the photo below so you can make sure this does not  happen you yours, as it will affect the performance reducing power and and making it erratic and unreliable. I have put the photo below. This gun had not been used a lot. For those that have a problem loading pellets and jamming into the 78 then the best way to load a pellet is to point the muzzle towards the ground, this allows gravity to pull the pellet into the chamber. If like a lot of shooters that hold the gun horizontal then the pellet (especially those with a sharp shoulder on the nose) will catch on the edge of the rising ramp that leads the pellet up into the chamber.

Tuning Kits & Parts