Poorly Airsporter Mk6, 0.22"

[PhatMan]

Hello to All,

Just stripped down my friends Airsporter Mk6 in 0.22"

The rifle was making ca. 5.4 ft.lb with 14.3 gr. pellets, so I would suspect is a bit poorly

The piston head buffer washer had totally dis-integrated, and the piston was a right sod to remove. The 'insides' were drier than a dry thing

I have ordered up some spares (standard spring, alloy piston head & seal/washer kit).

When re-built, what would be the 'par' energy I should be looking for - around 9 to 10 ft.lb ?

I was very surprised to see that the piston & spring guide were made from sheet metal, rolled into shape !

Definitely not what I expected from BSA & one of their 'flagship' models !

Have fun & a good Bank Holiday

Best regards

Russ

[landymick]

10.5 ft.lb is about right on these.

[Shed tuner]

make a new piston head (no buffer) to take a diana 28mm parachute seal; will make 11 FP+ easy (due to 6mm increased stroke, and better sealing efficiency). With the std arrangment, 9-10 Fp is plenty, as they get harsh.

[PhatMan]

John, Mick,

Many thanks

I think my friend will be happy with anywhere between 9 and 10.5 ft.lb

He just wants the old girl to be back on her feet, and shooting sweetly with it

Have fun & a good Bank Holiday

Best regards

Russ

[Benelli B76]

Russ, if the piston head was nylon you could have just skimmed it down (they expand through absorbing moisture) and there is a standard rubber tap washer that makes a good buffer washer. You just have to open the centre hole with a 10 mm drill. Done quite a few like this.

Regards, Baz

[Airsporterman]

Around 10.5 ft/lbs (factory spec) with a standard spring - but expect it to take a few shots for things to bed down after a rebuild!

ASM

[PhatMan]

ASM. Baz,

Many thanks

Yup - the head was a bit swollen - I will get a friend of mine to give it a skim.

If you partially cocked the rifle, the piston assembly didn't return to battery - it stayed where it was !

Have fun & a good Bank Holiday

Best regards

Russ

[Benelli B76]

ASM. Baz,

Many thanks

Yup - the head was a bit swollen - I will get a friend of mine to give it a skim.

If you partially cocked the rifle, the piston assembly didn't return to battery - it stayed where it was !

Have fun & a good Bank Holiday

Best regards

Russ

Russ, tell him to slightly cut the the grooves deeper where the steel ring and O ring fit as they also are usually shallower due to swelling.

Baz

[PhatMan]

Baz,

Ta

Can you please tell me the size of the standard O-ring on the piston ?

I have been 'attacking' the piston with some abrasive cloth as it was in a right state - the bearing surfaces of the piston have lots of nicks on them, as has the cocking slot. and there were random blobs of rust I have not gone for a full polish-up, but at least the surfaces are nice and smooth now

Have fun & a good Bank Holiday

Best regards

Russ

[LESS THAN FORTUITOUS KENNETH]

Hope you have better luck than I've had with mine! Nothing I've tried has altered it one iota. I've taken the buffer out and refitted the head to increase stroke. No difference. Tried several different o rings, from slack to tight. No difference. Changed standard spring for a titan no1 with a couple of coils taken off and refinished. No difference. Tap seems ok, but sprayed it with some teflon dry lube, hopefully to give a tighter fit, just to make sure. No difference. So, I gave up for a while, conceding defeat. Yesterday, after retreiving the teddy which had been evicted from the cot, I stripped it again and noticed the PTFE head looked a bit dodgy. On close inspection, the front was cracked, and yes, air was leaking through. I did a makeshift repair by supergluing some copper shim to the front of the piston and fitting another new o ring. Bit tight to get in, but quite slidy once in. Instant increase of 120 fps. Still low though at 7.5 fpe, but it is rising the more pellets I put through it. I'll probably try it with the old spring in just in case I may have taken too much off the Titan. I didn't bother doing a full relube as I was only testing to see if it was the piston head causing the headaches. At least I seem to have identified the major culprit. Obviously the head needs replacing anyway, so a kind member on here has offered to do me an alloy one with the Diana conversion. Hopefully this will crack it.

[PhatMan]

Kenneth,

I am desperately hoping that it will be less painful than yours was/is !

Wishing you much luck with your Airsporter !

Have fun & a good Bank Holiday

Best regards

Russ

[LESS THAN FORTUITOUS KENNETH]

Just put a few more shots down it to bed it in a bit more. It's .177 BTW.
With 8.44g jsb's 550 fps 5.67 fpe
With 8.4g superfield 610 fps 6.94 fpe
With Hobby 7g 680 fps 7.19fpe

All fairly consistant though. Just shows what difference a pellet can make though. Lighter seems more. I'm going to get some BSA Storm as I've heard they perform well in airsporters.

[LESS THAN FORTUITOUS KENNETH]

Another try.
Made a better job of the piston head and refitted original spring. New smaller o ring (probably a bit too slack). Power is up a tad with all 3 pellets producing similar power.

Jsb's 640 fps, 7.68 fpe
superfield 650 fps, 7.88 fpe
Hobby 700 fps, 7.62 fpe

Strangely, the Hobby have gone from producing the most fpe to the lowest fpe.

Now put a slightly bigger o ring in:
Jsb stiil the same
superfield 680 fps, 8.63fpe
Hobby 725fps, 8.17 fpe.

Shooting jsb's the cocking arm flips off the catch. It stays put with the other pellets. This is turning out to be a very strange gun.

[PhatMan]

Hello to All,

The poorly Airsporter Mk6 has been fettled.

It now has the Chambers alloy piston head, with the oddly rearward placed O-ring groove.

The replacement O-ring is ridiculously over-sized

We almost pulled our kipper getting the trigger block screwed in

The rifle now makes 7.5 ft.lb with the 14.3 gr. Crosman pellets (5.5 mm ), which at least some improvement ! ()

At least the tap does not leak

I have suggested to my friend that he gets an adapter made up to take the Diana 28 mm seal.

Can anybody let me know who could make him such an adapter ?

Can anybody please also let me know what modern 0.22" pellets are a suitable diet for the Mk6 ?

I thought I had a tin of 1980s vintage Eley Wasps, but I cannot find them

Many thanks

Have fun & a good weekend

Best regards

Russ

[LESS THAN FORTUITOUS KENNETH]

I don't have a sporter in .22, but I do have a Mercury. The best pellet I've found for that are Superdomes.