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.


 

BSA Mercury Rebuild

I think the BSA Mercury is a beautiful looking air rifle with the way the trigger block curves down from the back of the piston cylinder to meet the wooden stock, The chequering on the pistol grip, The short cocking linkage slot in the fore stock, and the slightly raised cheek piece. That's why i thought it would be a good idea to get her back to her former glory, so with a Titan XS main spring, piston washer seal, and a breech seal from J Knibbs i was on my way. 

This air rifle was given to me with a severe bend in the barrel at the breech block where it had obviously been fired with the barrel left open though this was an easy fix with a vice and a metal tube, and the forks that held the breech were very loose which again was fixed with the use of the vice. Also some one had put a spring from an SMK B2 in it and the breech seal was worn, which is what shall be adressed in this blog

BSA Mercury ready for working upon.

I removed the stock by removing the two cross head screws on the fore stock then the long flat head bolt at the bottom of the pistol grip, this is recessed into the grip and runs diagonally through the grip and screws into the trigger block.

Stock removed, note the long bolt that that goes through pistol grip.

To remove the trigger block i held the compression tube tight in a vice using leather to stop the vice scratching and gouging the cylinder, then there is a hole above and in front of the trigger guard in the block which an iron bar is inserted to give leverage in unscrewing the whole unit. As it came to the end of the thread i pressed a large block of wood behind it to stop the preload on the spring sending the trigger block flying,as it happens there was only two inches of preload which felt quite loose and the trigger block was  caught safely.

The hole in the trigger unit above and in front of the trigger guard is for using an iron bar for leverage

Then the cylinder, breech, and barrel were taped into the spring compressor to have the cocking linkage, spring, spring guide, and piston removed in a tidier enviroment than the work shed, basically the dining table in the kitchen

The spongy two inches of preload of the old spring.

The spring guide slipped out with two washers at it's base, one for supporting the spring and the other goes between the back of the spring guide and the front of the trigger unit. these keep the guide straight as the piston rod needs to pass through the guide and into the trigger unit, there it connects with the sear in the trigger unit which i had wrapped tape around to stop any pins falling out. Then the old spring came out, which seemed okay but the whole of the compression cylinder was in need of cleaning and lubrication.

The cocking arm linkage is articulated and once the cocking linkage guide and screw pin that connects it to the breech were removed, could now be removed and the piston could be slipped out the compression cylinder. The guide is held on to the cylinder by two cross head screws and holds a plate in place against the cylinder for the cocking linkage to slide against, it also has two tabs that fork out either side at 90 degrees for the fore stock screws. Where it connects to the breech there is a spacer washer that keeps the two walls of the linkage firm and tight, this is an easy one to loose if your not careful so i kept a watchful eye and it fell into my hand as i removed this end.

Old crumbling washer on the piston.

The piston head is held on to the piston body with a pin and a washer keeps the whole assembly firmly in place, but in this case the washer was well squashed and crumbled apart when the piston was removed. So i removed the the O ring piston seal and  cleaned all the parts with wet and dry and white spirits, then OOOO wire wool and white spirits , then with some kitchen towel i dried it out and removed any crud, and finished off with a final polish using Autosol on any parts that make contact with the compression cylinder.

Piston head and body cleaned and polished showing the holes for the pin

Luckily i had some tap washers that would fit the piston if i drilled the middle out to 10mm, however one was not thick enough and two was to thick.

Making the replacement washer

So i drilled out one and slipped it in place the after drilling another i managed to grind and file it to the correct thickness, so in the end one and 1/3  was just the right thickness to replace the washer. Some people have gone without the washer and drilled a new hole at 90 degrees to original hole further back,you have to grind down the end so the piston head fits but this does give you a tad more swept volume.

The new shiny smooth O ring seal below with the old tired one above.

The replacement O ring seal slipped into place on the piston head easily, comparing the old and new one showed me the original was worn and had streached with time and use.

I removed the compression cylinder and filed away any sharp edges, then went through the same cleaning and polishing routine i used on the piston.  Though this time all the materials  were clipped on to a slit in the end of some 6mm aluminium tube and wrapped around the end so i could get right down to the transfer port, looking at this made me think it quite a small diameter for a .22. The whole of the inside of the cylinder was shining bright when i had finished as i spent much more time and effort doing this part, it was then taped back in place on the spring compressor with some blocks at the breech support to bring the end of the cylinder over the end of the compression tube bed.

The preload of the Titan XS  spring, all 34 coils of it. In the fore ground is the old SMK spring.

The new Titan XS spring has 34 coils where as the the old SMK spring has 31 coils and was compressed a fair bit, this presented me with over four/five inches of preload which would surely test my DIY spring compressor. Also the curved shape of the trigger block meant that the end was off center for the threaded bar on the compressor, this was sorted by building a housing from two pieces of wood and some metal sheet. With the trigger block in this jig i could compress the spring while presenting the trigger block to the cylinder at the correct place and angle, once presented half a turn once the threads started to bite would hold the trigger block to the compression cylinder. Giving me time to remove it from the spring compressor and screw it into place with the use of the iron bar, though the last bit would need for it to go back in the vice and finish off screwing it together.

Trigger block in it's jig and compression tube just hanging over it's bed. I had to compress the spring by hand a bit so it would fit in the spring compressor.

Applied Abbey SM50 to the O ring seal and some Abbey LT2 grease to the last inch of the piston,then this was slid into the compression cylinder. Followed by the spring with both the ends polished, i had dabbed LT 2 grease over the front half of the spring then taking a cloth i spread it thin and evenly by wiping down and around the whole length of the coils, then LT2 grease was applied to the ends or the spring and the outside of the spring guide and both washers. The jig supporting the trigger block was lined up and placed  behind the rear washer with the threaded screw bar of the compressor directly on the back of the metal sheet at the back of the jig, this would allow me to turn the trigger unit 180 degrees when the spring was compressed enough so the threads would bite.

It took a couple off attempts to get it right in the end, and the spring compressor held together with the force of all the preload though i could see the poor thing staining. Once it was together the articulated cocking linkage was greased at the hinge, at the breech block on the screw pin and spacer washer, and on the tabs that go into the cocking slot and moves the piston so it cocks. The metal plate was slipped under the cocking linkage and the guide screwed back onto the cylinder, and then the stock was screwed back on leaving only the breech seal to be replaced.

When i cocked the gun i could straight away feel the extra effort needed for the new Titan spring but it was still easy effort, linkage and internals moved smoothly and made no noise. Putting a Wasp No 2 pellet into the breech i locked it back an took a shot, there was no twist or kick to speak of as the piston slammed home which was a definate improvement. I will have to knock up a slip washer and top hat in the fonley lathe when i get some delrin bar, but for now its just a matter of prising out the old breech seal and pressing the new one home.

I did have a lot more pictures for this blog but before i had chance to move  them over the computer stopped working, so it had to be re booted and anything put on since it was last saved two weeks before was lost. But some were moved over to the blog before this happened so it wasn't a total loss, any way i'm sure i'll be coming back to the Mercury some time in the future so i'll get some better pictures then.

TTFN

Wing Commander Sir Nigel Tetlington-Smythe. 

   

  

The Best Bits of Two Relums to Make The Tornado

Having passed on the Norica Quick to a friend i was left with the one underlever, that one being the old Relum Tornado. This one fired pellets well enough but was a bugger to cock, and seeing as i had a Relum Telly with no stock lying around i would strip both to fix up the Tornado. As all Relums have pretty much the same power plant and trigger assembly, i figured i could make a decent air rifle out of the two of them.

 Action and stock

 Taking the stock off the Tornado was just a matter of two flat head screws on the fore stock and the front flat head on the trigger guard, though i had to screw the sear adjustment screw right in as it's in the center of the trigger guard screw.

Front trigger guard screw with sear adjustment screw in side that

Unscrewing cocking linkage from the under lever cocking arm.

 Unscrewing the cocking linkage from the breech block and pushing it back to the circular hole on the spring cylinder was easy, however it does need to be gently prized out as the linkage is held against the cylinder by a strip of spring steel. This is because the cocking linkage is articulated, which is handy as the linkage slot on the stock is shorter and makes for a sturdier stock all round.

Leaf spring holding the articulated cocking linkage against the piston cylinder, for stock screws also screw into the sides of the metal bridge

There is a bushing on the linkage to stop it scraping the metal on the cylinder, in this case it was in good nick. With the linkage removed i easily pushed the two pins holding the sear and trigger out and with the trigger spring put them to one side, it was then ready to be put in the spring compressor secured with parcel tape yet again.

Two inches of preload on the main spring.

I compressed the end cap in a smidgen and tapped out the securing pin and released the pressure, two inches of preload on two springs one within the other running concentricly came out.

Both inner and outer springs look okay.

 Both springs looked in pretty good condition if not a little compressed with age, there was no spring guide as the inner spring does this job.

Nylon piston seal replacing the original leather one.

 However the piston was a real bugger to remove and needed some real force at times, there was a nylon solid piston seal with a bit of metal showing on one side when it should have been a leather two piece inner and outer seal which is held on to the piston head by a metal rivet.

Relum Telly ready to come apart.

Some very worn springs indeed.

I put the Telly in the spring compresser and repeated the same procedure, this time there was a fairly healthy leather piston seal but both springs were buggered. Even the inner spring was to short or compressed and some plastic tube lid had been shoved in there to take up the slack, both springs were worn with bends on them.

Telly piston on the left with leather seal  for the Tornado, next to the original piston.

 So i decided the healthy springs from the tornado would go back in, and the piston with the leather seal from the Telly would be the better option. Also the trigger and sear pins from the telly would be used ,as both pins on the Tornado had snapped in half.

I cleaned the inside of the piston cylinder first with wet and dry dipped in white spirit on the end a piece of 6mm aluminium tube, this has a slit in the top so it can clamp around the edge of the wet and dry which is then rolled around the tube. Though if there is a lot of crud inside the cylinder you could pop the tubing in a drill and shift it a lot quicker, but i prefer to do it by hand as you can take a little more care doing it.

Aluminium tube with wire wool dipped in white spirit cleaning the inside of piston cylinder.

Repeated the same procedure with some 0000 wire wool wrap around the end of the tubing, this takes a bit longer as i really want to polish the cylinder up. i followed up with kitchen towel and white spirit to remove any thing inside , then polished it again with autosol and kitchen towel to give it a really good finish.

I did pretty much the same thing with the piston out of the Telly with the leather seal , and let about 10 drops of Abbey SM50 soak into the leather for a good hour. I cleaned the springs with white spirit and sanded then polished the ends, then polished the end cap and as much of the inside of the piston where the springs touched. At a later date i will have to knock up a slip washer and top hat, but that will be at another time, not now.

Trying to polish the inside of the piston

Dabbed a little SM50 around the piston seal and some Abbey LT2 grease around the rear of the piston and pushed it in to the cylinder, it was a firm fit and a lot easier to slip in than the old piston. then dabbing a little LT2 grease over the first half of the springs , i took a cloth and ran it around the coils so the excess grease spread even and thin along the whole length as to much grease can bind and slow the spring movement.

The barrel, cylinder, and piston were taped onto the spring compressor and both springs placed within with a dab of grease at each end,the end cap from the Telly was placed at the end and then compressed.

Cleaned, polished, and lubed, the end cap is lined up for the pin holes.

I also used the end pin from the telly and tapped that into the end cap when it was aligned, and the original sear, trigger, and spring were fitted with the pins from the Telly.

Cocking linkage ready for a touch of LT2 grease and slipping through the bridge into place.

The cocking linkage was a lot easier to reinstall than it was to take out, and the linkage pin screwed back in.

The Telly's trigger, sear and spring next to the tornado trigger show how they work.

As the Telly trigger guard stock screw didn't have an adjuster screw, the original was used when the stock was screwed back on, and then the adjuster screw was screwed back out so the sear would engage.

Trigger gaurd stock screw with sear a adjusting screw inside that.

With both fore stock screws put in, the rifle was ready to test, it was definately a lot easier to cock now so some good was done. After loading a pellet in the loading tap i fired a shot at the target board, the trigger was stiff and needed adjusting and i could feel the main spring twist the rifle in my hands when firing.

Oh well, a top hat and a slip washer needs to be made at some point to stop the rifle from twisting, as for the trigger i reckon some adjustment and a good polish of the sear contacts will sort that out. In fact an aluminium piston head with an O ring seal instead of the leather seal could possibly increase the swept volume a little, but these are the things of future work and blogs.

Relum Tornado with Crosman 4x15 scope.

At least i managed to remove that unsightly aluminium hooded site that was on it when i got it, removed the two grub screws but had to cut it off as it had been fixed on with locktite. But i like this rifle, it's quirky and appeals to me so i'm going to tinker with it till it's running just right. Though that may take a while, at least it will be experience gained and you never know it might end up a decent springer.

TTFN

Wing Commander Sir Nigel Tetlington-Smythe.        

Sharp Innova Breech Repair

Now the Innova is shooting fine and holding air i should at least get get her looking good, and that chip off the back of the breech is not only a spoiler but doesn't allow the bolt catch spring to stay in place. I decided at first to shape a  piece of  8 mm flat bar aluminium and screw it into the back of the chipped section, but first i would need a flat surface to attach it to. For this i used a small circular grinding stone in my Dremel, which is actually made by Draper but i refer to it as a Dremel anyway.The surface was now flat and flush with the back off the bolt catch.

Aluminium plate that held the spring for the bolt catch , after grinding a flat surface.

However i discovered that the bolt i used to attach the piece of shaped aluminium bar was to long and it would press against the sear, so after a shot it would stay in place and let the firing pin move when i gave the rifle a pump. So i cut the bolt shorter and added a drop off abbey SM50 to the sear, now it dropped back down to the firing position and the valve held air again. i used a cut off piece off spring from a clipper lighter to hold tension on the bolt catch, then screwed the shaped aluminium to the flat surface.

The breech is made from a plastic and seeing as i make dread beads and stuff out of Fimo modelling plastic clay, maybe i could shape some Fimo while pressed against the space left by the missing chip then bake it. 

Cardboard in place to stop the Fimo from hindering the bolt catch movement.

 I would glue this with Locktite and drill a hole so the bolt would hold it more securely as well, i cut a piece off thin card board to place over the aluminium and around the bolt so i could not press the fimo to far and impead the bolt catch.I placed the aluminium bar under this then pressed the Fimo into place and shaped it  a little over sized, as i could  grind the Fimo after baking and fitting it so it would be flush with the rest of the breech.

Molding Fimo onto the back off the breech.

Pulling the soft fimo off the back of the breech i cut a notch for the the bolt pin on removal then popped it in the oven and baked it, i left the aluminium in the Fimo so i could drill a matching hole for the bolt.

ready to be drilled after coming out of the oven.

Fimo takes 20 minutes to bake hard at 100 degrees C  and has a little flexibility while still warm, so I quickly drilled a hole and a larger one to countersink the bolt screw on the outside surface. Dabbing a few spots of locktite on all the surfaces that needed joining, i removed the card board and pressed it firmly into place and held it there. Once the loctite had set i put a spot of it on the bolt screw and quickly screwed it into the countersunk hole and breech.

Fimo baked , glued, and screwed in place prior to grinding flush with the breech.

 After leaving the whole thing for 20 minutes or so to harden properly, the fimo was ready to be ground so grinde away i did,so now i'm left with a breech that looks the right shape.

Finished article with breech repair after grinding.

So now i have a complete Sharp Innova short of the rear sights, which i was given but i'm buggered if i can remember where i put them. Besides i dialed in a solid generic 4x32 scope at 12 and 25 yards on 5 pumps and it is so accurate that this one is going to be a keeper, besides i wouldn't get top money if i sold it because of it's original state and my repairs.But they are solid and good enough for me, i would recommend that if someone wanted a multi-pump that they should get one of these. I mean , Sharpsman on airgunforum has loads of Sharp Innova's and he swears by them, if your really lucky he might sell you one, but i doubt it.

These multi-pump air rifles are solid, accurate and a wicked design, it's a shame that no air gun company has taken this 1970's design any further.Webley now do the Rebel which is pretty much the same air rifle. But so far it has only come in .177 and has about 3 sets of ft/lb limits. So you better make sure which one you order or buy, and though some parts actually have Sharp printed on them i'm not too sure if parts are interchangable or if the valve is of the same design.Yeah Man , get a Sharp Innova, it could do with a raised cheek piece on the stock so your head is comftable with a scope. Mine is .22 and i can get pellet on pellet at 40 yards,these air rifles are the dog's bollocks to be sure.

I'm waiting now for some parts from J Knibbs so i can finish off working on other air rifles that i have already start writing the blog for, so it won't be long before some new blogs on some lovely springers will be on there way. 

During the repair of this air rifle i was mostly listening to Heavy Horses by Jethro Tull, Thank Christ For The Bomb by the Groundhogs , and Safe as Milk by Captain Beefheart.

TTFN

Wing Commander Sir Nigel Tetlington-Smythe   

Sharp Innova Spacer, Made Out Of Scrap

Now i had the Sharp Innova up and running just dandy, and believe me i am totally impressed with how good this air rifle performs. I got to thinking about the missing spacer that sits under the compression tube in the breech, well it's got to be there for a reason even though the stock thread and grub screw seemed to be sealing the transfer port without it. But on second thoughts it would stop the grub screw scoring the compression tube and help even out the pressure from that point, besides i had a load of assorted tubing in the scrap pile from which i could cut a new spacer.. 

.

Spacer slips in under the compression tube out of sight inside the breech unit.

I had seen photo's of it on different sites that sold Innova spares, so i had a rough idea of it's shape and size. I measured the diameter of the compression tube which was about 22 mm then found the nearest sized steel tubing i had which was 26 mm outer diameter and 1 mm thick,seeing as it only covers about 1/6th of the circumference of the compression tube i could squeeze it a little to fit. The spacer starts just inside the breech unit and forks around the thread screw that holds the exhaust valve in place and the collar for the stock screw, then the grub screw pushes  against this and the square nut in it's housing at the bottom of the breech unit.

Cutting out the blank for the spacer

Holding the steel tube in the vice i cut two lines to roughly the right length, then cutting across ways i was left with a blank i could grind down to the correct shape. Putting a grinding wheel in the fonley lathe i ground down the sides so they were even, this done i then ground into the one end to create the fork that would sit around the threaded screw. Next i thinned out both edges along the length so the sides would flex a little easier and the thicker middle would push the tube upwards, then rounded off any square edges and filed off any remaining burrs finishing it off with some wet and dry.

Grinding on the fonley lathe (fonley means 'if only' i had a lathe)

It was now ready to slip into place once i had given the edges a little  squeeze, I had already removed the stock so all i had to do was loosen off the grub screw. It fitted in easily though it didn't quite slip in, i pushed it into place and pulled it out a little just to see if i could for future removal.

Rifle, stock, and home made spacer.. Grub screw and square nut in the middle.

Pushing it back into place i tightened up the grub screw and screwed the stock back on, that was it, job done. I know i could  of got one from Chambers or J Knibbs for a couple of quid, but the postage is a bitch on one item and besides it was easy,fun, and took no time at all.

TTFN

Wing Commander Sir Nigel Tetlington-Smythe