BSA Supersport/Lightning tuning?

[junglie]

My lightning XLT groups great, but the scope has run out of elevation since I stripped it to clean and polish. Could the maxirail cause that or is the scope goosed? It was miles out before the strip out and that scope is no longer with me

only if you've re-fitted it wrong

[evert]

I've been thinking hard about a 25mm supersport conversion, and it seems to be possible.
You'd need to make a rotating piston with a skirt that can engage the trigger around the entire circumference, and it needs to be hardened properly at the skirt.

But the results I get with the original 29mm piston and a titian spring on tight delrin guides are very good.
Keep in mind, a lot of of the later barrels and cylinders have serious dimensional problems.

[look no hands]

I've been thinking hard about a 25mm supersport conversion, and it seems to be possible.
You'd need to make a rotating piston with a skirt that can engage the trigger around the entire circumference, and it needs to be hardened properly at the skirt.

But the results I get with the original 29mm piston and a titian spring on tight delrin guides are very good.
Keep in mind, a lot of of the later barrels and cylinders have serious dimensional problems.

I weighed the spare piston I have and it comes in at 231g so I'm not sure what the best weight for it would be?

Pete

[evert]

I weighed the spare piston I have and it comes in at 231g so I'm not sure what the best weight for it would be?

Pete

The Norweigian guns (FAC) have steel piston weights plus two steel washers in front of the plastic piston liner.
I remove the piston weight and fit a delrin tophat with the Titan spring. I keep the washers in front of the liner.
This gives 11-12fpe depending on calibre and gun, and a very nice shotcycle.

[maximus]

My lightning Tac is standard apart from fitted guides to the stock spring and shoots very well. I have added an adjustable breech bolt and shims and polished the trigger sears. The trigger is the worst thing about the gun but its well usable and not difficult to get great groups with using FAP. Personally I think a 25mm conversation is not required.

Regards Max

[junglie]

I've been thinking hard about a 25mm supersport conversion, and it seems to be possible.
You'd need to make a rotating piston with a skirt that can engage the trigger around the entire circumference, and it needs to be hardened properly at the skirt.

But the results I get with the original 29mm piston and a titian spring on tight delrin guides are very good.
Keep in mind, a lot of of the later barrels and cylinders have serious dimensional problems.

I've had a good few lightnings through my hands & even after tuning none of them lived up to my standards as a keeper, the only one that did was an early brum built full lenth barrel supersport all in .22, but they all require a specific hold too noticed they all benefit from a well lubed slip washer at each end of the mainspring which lessens the torque recoil on them well.(by this i mean a twisting motion on fireing)

[junglie]

The Norweigian guns (FAC) have steel piston weights plus two steel washers in front of the plastic piston liner.
I remove the piston weight and fit a delrin tophat with the Titan spring. I keep the washers in front of the liner.
This gives 11-12fpe depending on calibre and gun, and a very nice shotcycle.

I've found aa pound coin or two used as weights inside a couple as well as broken mainsprings in some too common on late 80's early 90's bsa's, found they all shoot smoother with no twang with the original lube sleeve in place too.

[evert]

I've had a good few lightnings through my hands & even after tuning none of them lived up to my standards as a keeper, the only one that did was an early brum built full lenth barrel supersport all in .22, but they all require a specific hold too noticed they all benefit from a well lubed slip washer at each end of the mainspring which lessens the torque recoil on them well.(by this i mean a twisting motion on fireing)

Yeah, thin polished steel washers are helpful inn all springers.
But I've not noticed the hold sensitivity of the Supersport, I find them to be easier to shoot than the Hw95 with the standard length barrel.
Now, the Lightning with its short barrel is a totally different story.

[junglie]

Yeah, thin polished steel washers are helpful inn all springers.
But I've not noticed the hold sensitivity of the Supersport, I find them to be easier to shoot than the Hw95 with the standard length barrel.
Now, the Lightning with its short barrel is a totally different story.

yes it was mainly the lightnings i noticed it on evert too ,.

[Andy001]

A few year ago, Looking at T20 tuning thread on the hw35 inspired me to look at an old Supersport.

I was playing around in late 2019 with an o ringed head on the Supersport piston.

Issue one, an overwhelming tight choke on the barrel
I did find a replacement which was better

Issue two,
I lost a bit of spring room due to the o ring head depth, needed to be made smaller

Issues three
A decent spring, I rebuild my standard gun which was bang on but I tested a few old springs which were cr@p

Issue four
Due to a bad experience I fell out with airguns. Also I need a lathe (shame I missed the one on here! Recently)

I think if any decent progress is made on these old bsa's a little bit of research is needed, a test mule is needed

1. Test pellet on scales, how much pressure it take to push the pellet through the barrel
2. Port size,
3. Piston weight
4. Spring length, coils,
5. Was the gun question making power in standard form (makes sure spring, tube is sealing) I had a few cylinders, one out of three would not make power with every part swapped over from the other two cylinders. I had no tool to test the cylinder

6. It's late and I can't remember any other tuning parameters from over a year ago as I've not done anything or thought about any information I gathered.

I'll try find my notes but I'm guessing they've been chucked out as I was going to redo it in the future.

7. Same applies to reduced cylinder modifications

Soz for the rambling, probably most of its rubbish

[merlin]

[IMG]WIN_20220101_11_50_47_Pro[/IMG]

my .177 brum Supersport XLT @24 yards, yes they can be tuned with LOTS of effort

edit, pic not showing thats annoying, anyway 5 shot grouping just under 6mm center to center about half the size of a 5 pence piece with AA express PCP territory id say and def on a par with my TX200HC, trigger needs yet more work i know it can do better, the .177 carbine barrels need lots of piston weight and i find a shortened spring reduces twang/resonance even with mated guides with the standard spring/length shot cycle being bloody horrible.

[look no hands]

Has any had to shim the maxirail? I've run out of elevation on my xlt

That won't be easy because it slots into the cylinder, so no adjustment that I can see of.

Pete

[El Garro]

Has any had to shim the maxirail? I've run out of elevation on my xlt

Is your barrel straight ?
Lay it on its side and look down the line of the top of the cylinder and along the barrel to check.
Only mention is as I've seen a couple of later ones and shorter barrelled lightnings with barrels bent upwards.
One was from an 'accident' while cocking but it straightened out easily, I wondered if the steel wasn't as good as they used to be.
It may not be the case but I thought best to mention it.