BSA Mercury, The Final Stages

For now.........

Sweet looking air rifle

When last i wrote a blog i had just finished fixing up the BSA Mercury, and left off with popping in the breech seal. However i realised i had forgotten to order one, just missed it out on my order from J Knibbs. So in goes another order for a Titan XS mainspring for the Weihrauch HW35, a flip up red filter for my gun lamp, and two generic BSA breech seals, I got two as i have a BSA Meteor which would benefit from a new one as well.

 When i gave the original Mercury breech seal a close inspection i could see why it needed replacing, one half of it looked liked it had been filed flat so one side was flush with the breech face and the other side protruded a smidgen to where it should seal. 

Worn old breech seal

When i placed a cigarette paper over the breech to see if any air escaped when fired, it didn't just move it, it shot into the air, and that was with me gently holding the paper to the sides of the breech with my fingers.

Ready to replace

The generic breech seals are made from a firm rubber and are white, where as the original is a black harder harder material, but that may be because it has aged and hardened. 

Two new breech seals, i have a Meteor as well.

It's a folded over circular seal with a small slit on the inner fold, and the fold is the side of the seal that faces the outer side of the breech. The old breech seal had to be prised out and as it was so old it came out in small pieces and crumbs, most definately well past it's sell by date.

Oh crumbs!

Though once removed and cleaned the new seal just slipped in easily and straight away i could tell the differance between the old worn seal and the new one, standing just past flush from the breech face and making a perfect seal around the transfer port. 

New breech seal fitted

Cocking the rifle and loading the pellet then taking the shot i could hear the pellet hit the back stop with a lot more force than it had done before. Though i would like to point out that according to a very well known and experienced airgun tinkerer (known to some as T20) reckons that most Wiehrauch breach seals would fit even better to Meteor's, Airsporter's, Mercury's, et al, and give you an extra 1/2 ft/lb as they are made from tougher stuff and are a tad longer. Anyway read his blog 'Air Gun Tech' and you can see for yourself that him and his buddies know their minerals, it all makes sense to me, sort of.

I also made an order to Uttings for a 6x40 AO Nikko Stirling scope and a set of Accushot high profile off set mounts, the mounts arrived but i would have to wait another week or so for the scope as they were out of stock.

Lots of bit's that come with the scopemounts

Scope mounts in the box

I have discovered that after buying loads of economy scopes in the past that it's best to spend a little bit more, though you don't have to break the bank doing this. 6x40 is a good hunting magnification and Adjustable Objective is pretty handy for guaging the distance of your target, and being a little short sighted i can use a scope with AO with my glasses on. However they didn't have any in stock several weeks later, so i reordered a 3-9x40 AO Nikko Sterling and i can just leave it on x6 mag for hunting

Ready to fit the scope

The one piece off set mounts are crucial for BSA Mercury's and any other BSA with the curved trigger unit, as the scope rails are set to far forward for most people to use comfortably with normal mounts. In this case i  mounted an AGS 3-9x40 scope and with the off set facing backwards found it sat just perfectly for my head an eye to line up, two hex bolts clamp the mounts to the scope rails and two smaller hex scope stops screw down to add extra support on the top or the piston cylinder. The Accushot mount came with three allen keys and one spare hex bolt in each size, this was handy as i had a one piece mount with a striped hex head so i popped it in there. The hex head was a little thicker than the others but it does the job fine, and now i have a spare one piece mount for one of my other springers.

Out in the back garden i sat down at 27 yards from my target and trap and took some test shots with .22 Eley Wasps No2's, The scope was fairly close to the POI but the shots were stringing vertically and some went left or right which showed me this rifle would need at least half a tin of pellets to settle down and a very gentle hold, though when i tried some .22 RWS Superdomes i found the grouping was a hell of a lot better but still not upto anywhere good enough for hunting. Most Super domes fitted snuggly into the breech though some were looser and deep seated themselves. However i could feel the wasp's click in snuggly, but they can be seen by eye that they all differ or are slightly deformed in some cases, and would explain why I found this a little odd as old BSA barrels are 5.6 mm and Wasp No 2's are made for this and they just did not perform that well, where as the super domes that fitted deeply where falling into roughly 2 inch groups which was without a doubt an improvement.

With the new main spring and lube this rifle slams the piston home with force but there is no buzz or twang which is a bonus, but for a smoother lock cycle it is in need of a top hat and a slip washer and 3 or 4 coils removing. I feel this air rifle is now performing close to if not a little above factory specks, but give it a bit of running in to settle the spring in and short stroke the piston and its going to be a corker of an air rifle which is not so hold sensetive.

I mean, i shoot at a dot on a piece of paper and my shots appear to go all over the place, but if i place a few bits of 1 x 2 inch wood on the shelf in front of my back stop and i miss one every 5 shots. So it seems i can hit an inch size object better than i can group an inch circle on paper, and that's at different ranges to boot. Now that's all well and good out in a field of rabbits where i originally learn't to shoot well, but i have to garrentee i can do that with whatever air rifle i am using at the time in order to make a clean kill. Most of my air rifles will allow me to do that out to 45 yards in some cases, but with this rifle as it is now i wouldn't like to take the chance, even at 15 yards.

 It would appear that i still have a lot of work to do on this lovely little Mercury, and as this blog is all about my learning curve with working on air rifle dynamics and the improving of my knowledge of said objects. Then it would stand to reason that i will be squeezing a few more blogs off this gun.

TTFN

Wing Commander, Sir Nigel Tetlington-Smythe.


 

Sharp Innova Dissassembly and Reassembly, Saved From The Dustbin

For a more detailed look at the Sharp Innova check out my more recent blogs '.22 Sharp Innova a restoration project' HERE  HERE,  HERE , HERE, or HERE

In my last order from J Knibbs  i decided to see if i could resurrect the Innova and got the complete seal and washer set, and a replacement pump head seal. With the back corner of the breech block chipped off exposing the bolt catch and unable to keep the spring in place, I wondered if it was beyond repair at all. But when I pushed the catch up and it held the bolt I thought why not, besides, I could always attach a small plate to hold the catch spring in place or something. But first sort out the valve as it would only hold under one pump of pressure which would slowly leak out, it sounded like the inlet valve was broken but it had to be taken apart to see. I had heard good reports about how good these Japanese Multi-pumps were, dispite all the plastic used to make them.

Step one was to open the pump arm all the way open so no air was compressed in the compression tube, this makes it a lot easier to remove the pump rod unit. You can remove the pump cylinder and exhaust valve without taking the front end apart, but i decided to dissassemble it so i could clean and polish as much as i could.

front hollow pin, though the photo was taken when i reassembled

I tapped out the front hollow pin which holds the front unit to the compression tube, i then removed the hinge pin next to it. This is held in place with a circlip and holds the pump arm and the front unit inside the compression tube, it is made of solid plastic and could now be slipped off the tube, inner barrel, and plastic outer barrel.

Pin holding the underlever to the piston rod unit coming out through the hole for the pump arm pin

With the pump arm removed i could pull the piston rod unit back and disconnect the underlever, tapping the connecting pin through the pump arm hole. The pin does not line up perfectly with the cylinder holes, with one side lined up 3/4 of the pin was visible on the opposite side and needed a smaller pin to tap it out. The piston rod unit could now come out easily, not only did i need to replace the pump head seal but the rod was in need of straightening out a little. There was adjustment at both ends of the rod, so after clamping the rod in a vice for half a day to remove some of the warp i made some adjustments to lengthen the pump rod unit.

 The brass hinge end was given two complete turns after releasing the locking nut and then locked back again, and the seal end was given three complete turns again with the locking nut to secure it.So now to get to the exhaust valve in the compression chamber inside the breech, I thought removing the stock would be a good idea for a start.

Brass collar in front of the trigger with the grub screw square nut set in the breech housing in front of that

By removing the front crosshead screw on the trigger guard the stock was removed revealing a brass collar, which i unscrewed to reveal a screw thread sticking out of the breech unit, this has a slot for a flat head screw driver and secures the valve in the correct place in the compression tube. In front was a grub screw which goes through a square bolt in the receiver body to press against a metal spacer which forces the compression tube upwards in it's hole in the receiver, which has a tad larger diameter. This seals the tube and valve to the barrel, but unfortunately no spacer  slipped out when the screws were removed as it was missing. Anyway the compression tube came out easily with the breech seal O ring in place, the O ring was put aside and the new one from the seal kit was sized and made ready for when it was reassembled.

Transfer port O ring seal sitting between the compression cylinder and breech unit, no spacer though.

Getting the exhaust valve assembly out was pretty simple with no pump arm still attached to accidently close and send parts flying out while dismantling, i made this mistake a while back much to my regret. The exhaust valve back guide was just under finger tight and unscrewed easily but only the exhaust valve spring and the spacer sleeve came out, there was no bumper or bumper plate but luckily these items came with the seal kit. Pushing a piece of dowel down the front of the compression tube the valve unit slipped out the back, if the pump arm was still connected you could slowly close this to push the valve out.

Valve air chamber and guide with firing pin, spacer, exhaust valve spring, and exhaust valve back guide

The valve unit consists of the brass front end air chamber screwed to the brass valve guide block with an O ring to seal them, when unscrewing them its best to be careful of the valve spring that holds the inlet valve ball from flying out. Stone me! They were hard to get apart, in the end i had to use two sets of mole grips and twist them because they were joined so tight. The mole grips left marks on both parts, but i sanded them down with some wet and dry till the were smooth. Now i could unscrew with my fingers and carefully caught the spring and ball in my palm and put them aside, i teased the old O ring out with small flat head screwdriver after sliding the firing pin out. I removed the small brass collar and the firing pin O ring seal from inside the guide, cleaned the brass parts with white spirit, put in the new O ring seal with a spot of Molicote and brass collar, then put on the new valve O ring, and put that aside ready to screw back onto the air chamber.

The air chamber itself Has a delrin seat for the inlet valve that is held in place with a screw in collar  and is a guide for the valve spring, it has two slots opposite each other at the top so a flat blade  would unscrew it. Shining a torch down the chamber i could see small nicks on the delrin seat explaining why it would not hold air, there was no replacement delrin seat but i then i noticed an unaccounted fat do-nut O ring in the seal kit that would fit perfectly in the hole for the collar to sit on. So i unscrewed the collar and teased the seat out with a pin from the outside of the air inlet hole, removed the outer seal, and cleaned all the brass up with white spirit. Putting it back together was a case of popping in the new do-nut ring, screwing in the collar to seat it comfortably, cleaning the ball and dropping it in place with the spring on top, then screwing the guide back into the air chamber so they joined but were not over tight. Problem sorted hopefully.

I then cleaned the compression cylinder with OOO wire wool and white spirit on the end of a piece of dowel, then polished the chamber with autosol as i don't have any GN paste. I slid the bumper on the longest side of the firing pin and pushed it against the collar in the middle, the other shorter side was smeared with molicote and inserted into valve guide. Making sure the transfer port and screw hole were lined up correctly i put a smear of molicote on the O ring and inserted the valve into the compression chamber until the holes were aligned, in went the exhaust valve spring followed by the spacer with the new bumper plate snuggley fitting inside the rear,and finally the exhaust valve back guide was screwed back in less than finger tight into the rear of the compression cylinder so it was flush with the firing pin.

I smeared a touch of molicote to one side of the transfer port seal and put it in place, then with the trigger pulled back i inserted the cylinder into the hole in the breech leaving space between that and the barrel to keep the seal seated. The hole for the theaded screw was lined up when the exhaust valve back plate rested against the sear and then it was a matter of screwing in the thread and the brass collar over that, then placing the square bolt in it's space in the breech i screwed the grub screw pushing the compression cylinder nice and tight against the under side of the barrel and sealing the transfer port. Now with the cylinder in place i reattached the stock with the crosshead screw in through the front of the trigger guard and into the brass collar on the breech, i was left with four small O rings which were two bolt seals each in .177 and .22.

 Taking the pump rod unit i removed the pump head seal by working it side to side and pulling, it was a black delrin type material with a flat face slightly raised around the outside with a pin size hole in the center and pretty worn all round. The replacment was of the same material but was orange, it had a flat face with a parachute design around the outside which i imagine would leave a little more compressed air before the inlet valve. It was hard to press it into the pump rod unit by hand, so i placed it face down on a clean flat surface  and tapped the pump rod unit with a rubber mallet till it fitted in place. I smeared three or four drops of Abbey SM50 arond the pump head seal and pushed the unit up the compression cylinder, and put every thing back together by reversing all i did to when i took it apart making sure to oil the hinges and grease the pins as i did it

Sharp Innova restored to working order

I gave the innova four even pumps which became increasingly harder, but were still little effort by the forth pump locking and unlocking smoothly at the end of each stroke. I loaded a .22 RWS Superdome into the breech, which for its size and with a 4x32 scope mounted on medium Hawke mounts is surprisingly easy to do and squeezed the trigger. Luckily the pressure of the bolt sping pressing the bolt  against the bolt catch kept the catch in place, but this is not at all reliable and needs sorting. The rifle fired with a low to medium crack and the pellet hit the target board from 27 meters with a hard and loud whack, much louder than one from my .22 HW35 or .22 BSA Mercury sounds at the same distance.

 I can confidently say that this rifle certainly has the minerals, it just needs the missing parts replacing, and some thing done about the chipped off piece at the back of the reciever. I'm sure i can make these parts myself or at least the bits i've mentioned so far, because it also appears all the parts for the trigger adjustment are missing and i have no idea what they look like. Anyway these are things to do next and will without doubt become future blogs, and i'll be sure to take more photo's in future so it'll be easier to understand.

TTFN

Wing Commander Sir Nigel Tetlington-Smythe  

DIY Sping Compressor

                                             

                                          

 In the past if i ever needed to compress a spring for one of my air rifles i would use the wood lathe, it was one of those jobs where you would clamp a drill in the headstock. The tailstock would adjust by sliding along a round bar then lock in place, it had a live centre which would wind in about four inches. By placing a wooden bed above the round bar and a block of wood over the hole for the drill in the headstock, i could then secure the spring and piston cylinder to the bed at the right height for it to be in line with the centre on the head stock. This worked fine unless there was a lot of preload on the spring but i usually found some way around that. However i had other plans for the wood lathe, and that was to convert it to a rudimentary metal lathe which i did. Unfortunately the conversion made it impractical to use it as a spring compressor anymore, and besides i really needed a bit more than four inches of movement when taking a spring out.

Makeshift metal lathe from old wood lathe

Having seen other DIY spring compressors on you tube and various airgun websites i decided i would have a go myself, and the sooner i did it the sooner i could get on with tuning up the glut of air rifles i was given. Not only that but its bloody freezing in the shed sometimes, and it would be a lot warmer to work on the kitchen table with some thing a little bit more portable with easier access to to the kettle


.

Cylinder bed

Framework for nuts and threaded bar

There was a load of various offcuts of wood in the shed, and instead of using an old G clamp i would use some 12mm threaded bar and nuts surrounded by a plywood frame and secured with metal putty. An old piece of wooden shelf was used for the base, the end block was very hard wood in which i cut a slot in for barrels to fit through. This was butted against three lengths of wood that ran part length up the base, the middle piece being a tad lower so an air rifle cylinder would sit comfortably.

Threaded bar clamped for cutting

Handy homemade disc cutter attachment for the drill

Bar lined up, washers and nuts in place for metal putty to be packed in

As the most pressure is pushed outwards against the two end blocks i decided i would strenthen and support them with metal brackets bolted to the bed, i then made a trough for a piece of hardwood to slide without slipping when the threaded bar is wound against the back of the rifle. When i tuned the Norica Quick the cylinder was held in place with strong tape, though later i drilled two holes in the bed and popped a couple of coach bolts through them. Now i could clamp a piece of wood strengthened by aluminium to act as a clamp.

Nuts held tight, metal bracket for extra support

Plastic strip for support trough

Admittedly it did not like the five inches of preload from the Norica's mainspring, but after a little settling in it did the job fine. This one will do for now but i have a load of metal frame and sqare section that will make a more permanent compressor, and this one should be able to handle a lot more pressure. But the odd jobs keep mounting and there is no telling when that will get done, let alone the tuning of my other springers and the Weihrauch HW35 most definitely needs a good check up as it's not as accurate as it used to be.

Just needs a few finishing touches