Polishing a Turd..... reprise

[Deleted member 408]

Gentlemen.....

Following the sad demise of AGF1... and so much valuable information and date being lost... (and I was not in a position to save so much of my own...), the ongoing and never ending saga of air rifle tinkering is still prevelant...

Therefore, I shall do my best to try and reprise a fairly popular thread that I covered in AGF1... and that being... can a SMK B2 be improved ... or in other words... can you polish a turd!!!

Please bear with me on this as alot of the "finer details"were not documented and my memory isnt what it used to be.. ...

This thread will be in sections that covers each specific component of the ubiquitous B2... so... PLEASE.. may I as that you do not comment or "break the thread" untill I have managed to compile ALL the components tinkered.. and in doing that.. we will be able to continue the thread from start to finish. It may take me a few days.. but if I can ask you hold off from commenting that would be GREAT...
It will be a mainly pictorial thread with comments and findings as necessary.

So here we go....

It was decided to get the "cheapest and nastiest rifle possible" and to see what improvement could be achieved in both looks and fuctionality. The B2 fitted that criteria perfectly. Brand new, in the box with all its glory... and costing me the princely sum of £49...

A simple and very rudimentary action... however... looking athe the "lines of the rifle" there seemed to be an optical illusion....


NO..... no hoptical dillusion... the barrel is bent at the breech.. (this will be spotted even more in a later section..)

The first job is to strip it down.. and see what we have got..



Seeing the barrel droop, it was decided to attack the barrel first once the rifle was stripped.

The stripping proceedure is simple enough, but you will need a spring compressor to effectively dis-assemble it .


Next section.... the barrel....

 

[Deleted member 408]

THE BARREL....

In typical "manufacturer stylee" the crud put in the barrel bore MUST be the dregs out of a tractor sump...... I took quite a bit to clean it so that it pulled through clean...

Also the crown looked like it had been bitten in

The length of the barrel was also a tad on the long side so that was gonna be shortened (my preferrance) and so the front sight had to be removed by gently tapping the dovetail section to ease it out...


Cue the grinder and then into the lathe.


.. and hey presto.... a screwcut end and a propper crown.. BUT... clocking the barrel up threw a whole new spanner in the works...

When spinning the chuck the breech end was nearly 2mm out of concentricity......!!!!
PLEASE NOTE THE SMALL DIAL(those are millimeters..)

The barrel was bent as it entered the breech to "give the appearance of a straight barrel when the rifle was cocked).

So it was necessary to straighten the breech in the lathe... This was done using the tried and tested method of "a large bar and 3 wheataboix" method.... However, I managed to get it within 0.2mm concentric...


There were other issues with the barrel, which I shall cover in the next section with regards the breech seal...

 

[Deleted member 408]

THE BREECH....

This area in itself is a contradictory in itself.. the actual seal is made up of some sort of out of date blue jelly and is as much use as a chocolate teapot..... It was not clean, defined and didnt allow the breach to seal properly..


It was decided to cleasn up the pellet lead in of the breech so once in the lathe the gunk was cleaned off and a nice SMOOTH lead in was ground in place...


However, we still had the hard jelly seal.. which was to be worked on .. so out came the pickers and the blue rancid jelly was removed.. to find a whole new kettle of fish..

The recess for the breech seel is machioned into the block and has a flat face on the bottom (which ios normal).. BUT the breech seal face is angled and to the depth of the seal varies from top to bottom.
Also the whole are looked like it had been machined with a very blunt instrument.. and there were burrs a plently.


Out came the diamond burr and a thoroughly good clean up..


Then we had to sort out the actual seal... so obtaining a generic (and cheep) O riong, I placed it in the breech seal recess to see how it fitted..

As you can see the differential on the top to the bottom of the sealing face. so I needed to remove some of the O ring material to allow the breech face to have a flat sealing face.

This technique was done by placing the O ring in the freezer for a while... and then (when cold and harder).. sanding the face on s aflat surface to the correct clearance

Once somewhere near, it was offered up back into the breech for "final fettling" and to make sure the rubber seal face was uniform.

Once that had been done, I knew the rifle would breech correctly, seal correctly .. and the barrel would no longer have its droop..

Next section.... the cylinder...

 

[Deleted member 408]

THE CYLINDER.....

Once you have stripped the rifle down you have the cyclinder and all its foibles.. the main ones being rough finishes, sharp edges and a "general lack of decent engineering finish"...

You will notice thet the cocking slot has sharp edges that Messrs Solingen (the cut throar razon manufactureres) would be proud of.. and the finish of the bitten out slideway is bad at its best..

Therefore, a small flat file, some varying degrees of emery paper and a comfortable chair and you are ready to remove all the rough edges and surcaces of the cocking slot bot inside and outside.

In areas inside the cyclider where tapped holes had been drilled through, there were burrs and scratches that would damage the piston seal.. so I used a small bore cylinder honing arrangement to polish the inside faces out...

PLEASE NOTE... on this photo.. you can clearly see the score marks on the inside of the cylinder where the piston glides... This was due to a MAJOR issue with the rifle which shall be covered in the section.. The Piston... (a stiff drink is neaded for that section..)

 

[Les]

Wow, you have some serious skills, Sir!

I had a B2 several years ago, and to be fair, for the price it was OK. Yes, it was twangy and sounded like a tin full of bolts, but it was reasonably accurate. I think I paid £40 for it, but it did come with a [ .... drumroll .... ] 4x20 telescopic sight! The crosshair snapped after about the fifth or sixth pellet, but I got a few months out of the rifle before the leather piston washer called it a day. I probably could have kept it going, but for £40 the easiest thing to do was to take it to the recycling centre, modifying it with an angle grinder to make sure it was dead.

 

[.20 Hunting Legend]

Wow, you have some serious skills, Sir!

I had a B2 several years ago, and to be fair, for the price it was OK. Yes, it was twangy and sounded like a tin full of bolts, but it was reasonably accurate. I think I paid £40 for it, but it did come with a [ .... drumroll .... ] 4x20 telescopic sight! The crosshair snapped after about the fifth or sixth pellet, but I got a few months out of the rifle before the leather piston washer called it a day. I probably could have kept it going, but for £40 the easiest thing to do was to take it to the recycling centre, modifying it with an angle grinder to make sure it was dead.

Thats the best way modify those guns . Angle grinder .

 

[.20 Hunting Legend]

THE CYLINDER.....

Once you have stripped the rifle down you have the cyclinder and all its foibles.. the main ones being rough finishes, sharp edges and a "general lack of decent engineering finish"...
View attachment 19658

You will notice thet the cocking slot has sharp edges that Messrs Solingen (the cut throar razon manufactureres) would be proud of.. and the finish of the bitten out slideway is bad at its best..
View attachment 19659View attachment 19660

Therefore, a small flat file, some varying degrees of emery paper and a comfortable chair and you are ready to remove all the rough edges and surcaces of the cocking slot bot inside and outside.
View attachment 19661View attachment 19662View attachment 19663

In areas inside the cyclider where tapped holes had been drilled through, there were burrs and scratches that would damage the piston seal.. so I used a small bore cylinder honing arrangement to polish the inside faces out...
View attachment 19664View attachment 19665
View attachment 19666


PLEASE NOTE... on this photo.. you can clearly see the score marks on the inside of the cylinder where the piston glides... This was due to a MAJOR issue with the rifle which shall be covered in the section.. The Piston... (a stiff drink is neaded for that section..)
View attachment 19668

You really are showing your skills , i hope all the hard work has paid off .

 

[Deleted member 408]

THE PISTON.....

This is the living breathing heart of the springer.... BUT as I was to find out ,,. mine had a HUGE defect....

Once the piston emerges from the cylinder you are greeted with a black mass of rough steel with the odd spot of corrosive finishes on the surfaces.. The cocking slots are rough and growly, the piston head and seal are usually covered in crud and there is a "general messiness" to the whole component...

However.... what I was to find next trully defied the engineer in me.. and gave cause to SERIOUSLY question the |hinese QC for this rifle..
Here is a photo of what I found.....

Hmmm, can you spot the problem?????

Heres another 2 photos... and carefully compare themmm

Can you see that the piston head.. is NOT centrally located onto the piston body.. it is offset by almost 1.00mm TIR and its welded in place too.


This is the cause for the galling marks inside the cylinder and the reason why the piston assembly was so hard to withdraw from the cylinder bore.. also.. when firing there was a serious deficiency in power and a resistance in cocking the rifle....

SO.... out came the grinder and the welds were removed and the existing piston unscrewed... thye faces wewre cleaned and prepared for re-locastion of the piston head..
The central hole was drilled and tapped M8 (as opposed to the M6 factory hole..). an M8 bolt was prepared and loctit3d into position , cut and then the whole piston body face was cleaned up again (once the piston diameter was running within 0.05mm concentric..)


Witht the hole plugged up, a new M6 hole was drilled and tapped making sure it ran perfectly in the centre of the piston.
The old piston head was then screwed into place and with the aid of a couple of TIG tack welds.... the head was fixed permanently and in its correct location.


The whole lot was then checked for concentricity and polished up ready for the next stage...


Part 2 of the PISTON follows.....

 

[Deleted member 408]

THE PISTON.. part 2....

Well, whilst we have the piston assembly out, cleaned and polished... I decided to assist the efficacy of the piston.. so why dont we piston ring it... and we did.....

Below are the photos that document the piston ringing of the assembly... I hope they are self expainatory..

... and there you have it!!

 

[Deleted member 408]

COCKING ACTION STUFF.....

So..... as we trawl through the "betterment of the B2".. our next project is the cocking assembly.. both the cocking lever and the barrel break thumbcatch..

Once more the SMK QC Dept have deemed it necessary to have rough edges and sharp corners on EVERYTHING including the cocking shoe.. This in turn with the roughness of thew cocking slot and piston slot can cause galling and grounchiness of the action when actuially cocking the rifle..


So.. in order to eliminate this we need to polish and deburr all the edges on the cocking shoe thus...


In an attempt to m=smoothen the cocking lever action even further and reduce the chance of any possible galling of the arm on the undersiude of the cylinder... I decided to fit the cocking arm with a delrin wear strip. This now means that rather than any steel to steel contact as you cock the rifle, there is now a delrin wear strip to "ease the cocking action"

This was made with an old bit of delrin, filed to width and pressed into the gap of the cocking lever. Then it was filed down to within 0.5mm above the arms of the cocking lever.


And finally for this section.. the barrel break catch. At best, it works okay, at worst, it sticks, grouchy and not always effective... so... a quick srtrip down, a deburr of the edges and holes pluss the main face was sanded flat to stop any distortion and or binding of the catch.

 

[Mr Bond]

A highly polished turd indeed Hal.

Well done mate.

 

[Deleted member 408]

THE MAIN SPRING.....

The spring............... a simple structure with ONE main job to do... produce energy....

However, a spring is a very complex item especially whefre there are a number of mitigating circumstances to complicate the effectiveness of its operastion.

Readers will note from the images that there are a number of issues with the B2 spring that (in my opinion) that MUST be addressed before re-installing .

The spring ends.... square and rough.


The end of the spring not square to the body (this imparts angular loading of the compressed spring therefore decreasing efficiency and forcing the spring to "angulate" in its housing, potentially causing steel on steel contact and or galling..


So, we need to get the ends square and taper all the harsh corners to increadse the springs effectiveness.. Thios is done using a dremel tool for de-burring and a grinding disc or linisher to get the ends square to the body..

We then go about polishing the surfaces of the spring to once make it even more smoother and efficient..

A delring top hat guide for the piston end of the spring is made.. then a spring guide is made to ensure close quarter running and as much cenralisation as is possible to make the whole assembly smoother and quieter...

And then we offer it up to the piston....

 

[Beaver]

Fantastic write up
Sounds like you’ve enjoyed this project
What it’s all about

 

[Deleted member 408]

THE STOCK......

The quality of the wood is PANTS... that is a statement that will resonate with EVERY one of you chaps who decided to strip the orange brown paint off the wood to see if we have a chunk of tigger beech under the lacquer.... WRONG... The screw fixings too.. horrible NASTY steel with cheese consistency heads that split and splinter when you try to do owt with them...


Nasty wood, split wood, filler and a total lack of anything that would even resemble owt half decent......



So I decided to modify the stock (with warts and all) into summat that may resemble a piece of char grilled timber (sui sugi ban).. but only after I have got the rasp, linisher and drum sanders on it...


Ha... and now... the best bit.... setting fire to it with a blow torch....


And after a good wire wooling of the charred surface..... a few coats of oil to seal in the finish....

I have purposefully left the splits in the wood as a reminder of the quality of the timber and as a feature..

I was considering a section on the trigger but I may just leave that as an addendum... as there is virtually nothing you can do to maker it better... BUT I did try..

 

[Shabby]

It was decided to get the "cheapest and nastiest rifle possible"

You certainly succeeded on making that choice - a truly appalling contraption!

 

[Deleted member 408]

And so to finish this little episode..

THE REBUILD.....

From the initial components of the ubiquitous B2.....

A Phoenix arises from the (literal) ashes....

The re-worked components all lined up ready for re-assembly...

Final tweaks to some areas removing any sloppy gaps or excessive play like the cocking arm front pivot and breech arm shims


Quality moly grease was applied as necessary to the areas that needed it. Some of the re-worked and machined components were re-blued and slowly... and methodically... she was rebuilt...


A decission to make a moderated barrel shroud was undertaken.... so I made it....

.. and finally completed my project...



And when it was all done..... the chrono told no lies as to the improvement of the B2...

Averaging at about 8.6 - 8.7ft/lb... and quiet enough to plink in the garden

 

[Deleted member 408]

THE ADDENDUM.....

The trigger is worst than a trebuchet mechanism.... PERIOD..... BUT it was possible to polish some of the mating steel surfaces to get them smoother... and to stop the trigger spring from grating over the high spot on the trigger steel.



The dremel and diamond burr was taken to the angled section of the trigger steel and a groove ground in to allow the spring to work inder compression rather than flexed compression. This smoothed out the pulling of the trigger blade and there was a very slight improvement to the actual release of the compressed piston.


However... the trigger is still crap... Just saying it as it is....

And so now..... the B2 looks like this......

Gentlemen... I hope you enjoyed this little presentation and I sincerely hope it gives YOU the impetus and desire to tinker with your own rifles...

Thank you for your time and patience...

Hal

 

[Buryal]

Thanks Hal for taking more of your time to reproduce how you did this classic fettle.

 

[franksy]

Great read and a great project

 

[Deleted member 408]

Thanks Hal for taking more of your time to reproduce how you did this classic fettle.

Heyup Al... your welcome mate.. As mentioned if it "de-mystifies" the fettling of a springer and gives lads the confidence to have a go at tinkering with their rifles.. well... jpbs a gud un..