Monday, 30 May 2016

Holdsy''s Innova

Hello every peeps, it's that time again. Time for a blog on another .22 Sharp Innova, this time it's gonna be completely stripped, resealed, overhauled to make it efficient as possible, and lovingly put back together.  Whilst not working on it in a sterilized enviroment, it shall be laid to rest on a bed of crushed velvet.

And this i had too collect from the Post Office as i was still asleep at 8.20 am when parcel force knocked on our door.

The reason for doing this is that it belongs too a fine chap who goes by the monicker of Holdsy, he lives in the flat lands of east England and had posted the action and two different sets of replacement seals for me to work with.

After unwrapping tape , box, and bubble wrap, this is what i would need.

Holdsy's Innova looked in excellent condition but had a few niggling problems with it,these were that it  took 10 pumps to reach the 12 ft/lb mark, the loading bolt had the wrong O ring seal and would not shoot back when the catch was released,\ after it had been left standing for a while.

Stripped Innova and tools used.

So seeing as i was sort these problems and reseal the exhaust valve i decided to strip his Innova right down, just to be on the safe side if you know what i mean.

One fat over sized rubber O ring replacing the original double set.

 This was just as well, as i found the front sight unit that holds inner and outer barrel, compression tube, and pump arm in place had one of its jaws broken clean off.
The front end cap that had the broken jaw, now as good as new...ish.

 However i managed to clean it in white spirit and glue it back in place, using a quality super glue made it as good as new, almost (i wouldn't go testing it with a hammer any time soon, but it will withstand the contant strain produced from the pump arm working).

Holdsy's .22 Sharp Innova stripped right on down, coulda gon further but it wouldn't all fit in the picture.

Holdsy had supplied me with both the T R Robb valve repair kit and the J Knibbs valve repair kit, i decided to use the T R Robb kit for the valve which has a firing pin and spring with it. As well as some silicone grease and bottle of lubing oil this in my opinion is the better of the two valve repair kits, this one i used on Holdsy's Innova valve

J R Robb Sharp Innova seal kit.

The J Knibbs kitt has a spare buffer plate and two sets of O rings for the loading bolt, i have seen at least three slight variations in bolt design on the Innova. Holdsy's Innova had one oversized O ring at the tip of the loading bolt, this was causing it to stick when the bolt catch was released.

T R Rob kit on the left, and J Knibbs kit on the right.

Two sets of two O rings of slightly differing dimensions should give you a set that would seal and not let it stick, the thinner of the two sets sealed perectly and stopped the bolt from sticking.

Loading bolt, bodge job O ring (that did seal well, too well), and the two sets of double O rings that came wih the J Knibbs kit.

I reckon the forward assist spring for the bolt was on the weak side, but seemed to be working fine now it was back in the reciever block.

A .22 Sharp innova with all original parts should give you roughly 12 ft/lb when the pump head is adjusted so the face of the pump head and inlet valve touch at the end of a stroke, this took 10 pump strokes to reach 12 ft/lb. So the first thing to do is adjust the pump head assembly to top out at 12 ft/lb, first releasing the bigger brass locking nut,

Unlocking the brass lock nut so the air release valve housing can be removed.

Then i removed the release valve outer body too check on the inner spring and blow off seal.

That spring holds back a lot of Pressure

All seemed hunky dory there so i screwed it back in place, and set to adjusting the rod assembly length so pump and valve touched ( 217 mm).

The air release valve housing about to be locked in place with the brass locking nut.

Working out the the length took a hell of a lot of tiny adjustments but once it was found the rest was easier.

Silver lock nut holds the air release valve securely in place.

Once the blow off valve was set to ones desired muzzle energy, the silver lock nut on the rod could be loosened and the newly adjusted release valve unit could be moved so the whole assembly reached the magic 217mm. 

However something was amiss, Holdsy's Innova would only reach 12 ft/lb after six pump strokes. This would be more noticable if one wanted to go FAC which would take 20 instead of 12 pump strokes to reach 20 ft/lb (pellet dependant).

I took it apart again to make sure the firing pin was well clear of the transfer port, i took the compression tube out to make sure the air inlet hole in the barrel was properly aligned with the transfer port in the breach block, i even took loads of measurements with the vernier calipers to make sure everthing internal was in the right place. I was stumped, i hadn't a clue  what was up.

So i looked at the trigger, for change is as good as a break after all. It's a lovely trigger because it's the first Innova trigger that still had it's first stage  adjustment screw still in place, 

The trigger adjustment screw does make a difference.

Just one more thing that makes Holdsy's Sharp Innova so nice, Triggers that release an exhaust valve get stiffer the more pump strokes one adds, so adjusting the first stage shorter is a lot of help and therefore a little easier.

Another view of thefirst stage trigger adjustment screw.

Eventually i realised what the problem was with the needing two extra strokes to make 12 ft/lb was, it was fitted with a later J Knibbs parachute style pump head seal. The outside face of the air inlet valve has a flat surface with the last two mm bevelled backwards at outer circumference, 

This is the shape the pump head seal has too mirror for best results.

the original sharp pump head seal, and even the T R Robb replacement O ring pump head seal sit flush even at the bevelled circumference. There will be trapped air the same PSI that is stored in the exhuast valve body in the V of the parachute pump head seal and the bevelle on the valve.

The orinal Sharp Innova pump head is made from Black delrin type plastic, but when it's damaged the whole thing is junked and is bloody impossible to remove without destroying it.

The T R Robb pump head seal is made from stainless steel with two rubber O rings used to seal it, pretty much the same set up as BSA Meteors and Mercurys use on their piston head seals. You also need to cut an half inch UNF thread into the pump head assembly for it to fit, looks the best though i've never fitted or used one yet. And they don't work on the newer Webley Rebels either.

The J Knibbs pump head seal is made of an  orangey red delrin type plastic and just clips into place, though just like the Innova seal it's a bitch to remove. If you don't mind six/seven pumps per shot they are fine, and half the price of the T R Robb seal

I'm sure there was a lot of fiddling about with this rifle that escapes my mind at the moment, as i had it for about four weeks and tinkered with it most other days. But the seals were changed, the bolt unstuck, overhauled and made as efficient as possible with what parts i had to hand. So that's it for now, and thanks too Holdsy for letting me work on his splendid Sharp Innova.


Best wishes, Wing Commander Sir Nigel Tetlington-Smythe



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