Thursday, 4 April 2013

Tuning the Norica Quick



Seeing as i was passing on the Norica to my mate i thought i would give it a bit of a tune up, besides i needed to drop the trigger pull a bit as well so kill two birds with one stone. Also it would give me a chance to see how the spring compressor would work out, i reckon there must be some preload as it is quite heavy to cock.

Preload is from the start of the wider trigger slot
The first thing i did was to check out the exploded view on Chambers http://www.gunspares.co.uk/shopdisplayproducts.asp?id=24977&cat=Quick, this makes life so much easier. Two plastic tabs either side of the fore stock revealed screws facing diagonally up into the cylinder block, and two screws on the trigger guard the rear one connecting stock to cylinder removed the stock. The safety latch was connected on to the trigger guard, pushed in place by the cocking linkage when cocked. The trigger unit held a nut for the rear screw and two pins held it in place to support a washer, spring guide, and the main spring. The rear of the trigger unit protruded from the cylinder by one millimeter and when pushed flush removed the two pins, however the unit could only be removed by pushing the washer and guide unit forward and slide it forward and out the wide long slot in front of it.

spring and washer pushed forward and trigger unit slipped out forwards
Handy device for removing trigger block and then letting spring and all free
I made a tool from two fat lengths of ali bar bolted to a half inch length of copper pipe which i hammered square, the bars would then fit between the outsides of the trigger unit and the inside of either side of the cylinder. With the cylinder supported on the spring compressor by using parcel tape of all things, i was able to wind the washer and guide forward two inches so i could tease the trigger unit out through the slot. Unwinding the pressure off the spring soon started to become a little alarming as the compressor was fully unwound and still under tension but i could push this by hand and slip it off, it would seem that this air rifle has four inches of preload and six if i included pushing it forward for removing the trigger unit.

Held down by loads of parcel tape
Handy device being slipped between trigger block and cylinder walls

I removed the guts or the rifle which was pretty dry except for a spot of oil behind the nylon piston seal, it all seemed in pretty good nick apart from where the piston had rub a little on top of the cylinder. however the end of the main spring had not been ground flat, and the sharp ends had left a ring of tiny marks on the top hat and the metal washer on the inside of the spring guide. The mainspring itself was in near new condition but where the sharp edges had nicked the tophat and washer there were minute flecks of metal scattered about, the piston was heavy with an inner sleeve which was a tube with cocking and sear latching cut into the outer layer.

Spring as it came out of rifle
Both ends ground down flat and polished
Right then, what did i do? Oh yes now i remember. First off i ground down flat both ends of the spring and gave them a polish, then  sanded the washer and tophat with wet medium then fine wet and dry' then polished with OOO wire wool the tophat, spring ends, and washer that all connected with each other. I then cleaned out the piston cylinder with white spirits and wire  wool on the end of a piece of dowel then polished and cleaned out any old crap left in there with a J cloth on the same dowel. Mmmmm shiney smooth. The piston was polished before the seal and at the end, and all deburring was done with my trusty Dremmel.

Heavy polished top hat and piston seal
this is one heavy piston i can tell you
Putting Abbey SM50 oil around the base of the piston seal and Abbey LT2 grease of around an inch at the end of the piston i slipped it back into the cylinder, LT2 grease on the end of the tophat and slipped that in the piston, the spring was then liberally coated in LT2 and then inserted making sure both ends had a tad extra grease applied was put in, then the spring guide and washer was smeared with a little extra LT2 grease and popped into the main spring.


Just some handy shit to have around for tuning

Before reversing the whole process of using the special tool to slip the trigger unit back into the slot in the cylinder i used the Dremmel to grind the sharp edges off the sear and piston, but only a little as i did not want to mess it up big time. Carried on putting the Norica back together and put the scope back on, which with the stop on it should not interfere with its previous POI.

spring pushed back in so trigger block can be replaced
Out in the back garden and took a five shot group, though sometimes i perfer a ten shot group. Anyway the trigger pull was down and there was most definately room to take more off, and the grouping was tighter and three inches above point of aim which means that it is now putting out more power. The rifle was also not so hold sensative, which i would call a successful tune indeed. What more could you ask for, i am indeed one happy little marsupial.

As i said i could lighten the trigger some more, but i shall leave that up to my mates discretion . Me personally, i would take it down a lot more but then i am used to being spoilt on Record triggers

TTFN

Best Wishes, Wing Commander Sir Nigel Tetlington-Smythe DOA OBE MBE FOAD 












 

2 comments:

  1. Very informative blog, Sir Nigel. The photos help a lot for understanding.

    Glad you found allmusic informative. This morning I am diving into some Richard Thompson.

    Have a good one. ~Ken

    ReplyDelete
  2. Arhh, Richard Thompson sing Beeswing, i could fix air rifles all day listening to that one, enjoy.

    Sir Nigel

    ReplyDelete