Supersport barrel/caliber change?

[TonyL]

Yep, agreed with to a degree, but all I'm saying is that, this was a .22, so the internals have not been altered. It's doing more than healthy power output in the smaller calibre, so no need to tweak for more power, which would usually result in harsher cycle, recoil etc.
I did own a .177 S/Sport many years ago and thought that it was a pretty nasty piece of work, to be fair.
If the standard set-up was different between the different calibres, especially the mainspring, this would indeed feel harsher. And I have been playing with tuning springers for over 36 years, granted on a small scale, for various friends, club members and my own guns.

However, maybe more through luck than scientific calculation, the OP has dropped on a tune, using various different parts, that gives very similar energy levels in either calibre.

To my mind, because this rifle was a .22 to start with, and all he's done yesterday was to fit a .177 barrel, there should be no difference in recoil or feel. We're talking the same bore and stroke and hence swept volume. We're talking unaltered transfer port so no change to static comp ratio. The only difference is going to be a tiny bit less volume in the pellet skirt, and maybe a tiny bit more pressure initially, affecting recoil surge, due to the narrower bore barrel and smaller volume contained there-in.

[TonyL]

Clearly a heavier spring is not the cause of harsher firing cycles because he has only changed his barrel but getting very similar power t.

The OP did not report a harsher firing cycle

Also, as he's said, getting it on the range properly may (or may not) highlight problems.

If this were the case, then there would be scope for reducing both the first and second stage recoil. This would, however, involve more work and experimentation. Reducing the stroke would make it sweeter. I don't know the swept volume of the Supersport for sure, but, as they're more than capable of producing power levels in excess of our limit, there's a definite option there. Lightening the piston may also help, but that would tend to help with the first stage of recoil and might make the surge worse, which, as has been pointed out, can be the major cause of hold sensitivity. I seem to remember that the TPs are pretty short on these, and I'm not aware of the diameter, but there's probably a little scope to open up the TP slightly, aiding air flow and reducing pressure on the piston face and hence surge.

As you'll know, tuning a springer correctly, any springer, but especially a lighter one in the smaller calibre, is all about the question of balance. Balance in terms of swept volume, TP diameter, spring length, rate etc., piston weight, stroke etc. etc. Get it right and they can be exceptionally sweet.
If the OP is committed to the project and wants to take it further whilst retaining the smaller calibre, there are plenty of options. It all depends how much time, work and money he would be prepared to invest, but the options would definitely be there to explore.

Have fun tweaking!

[TonyHolden]

Dan, it's great reading your results, it sounds like you may be on to a winner here. It's interesting reading what you say about the recoil and it's had me exercising the grey matter quite a bit tonight, with a few interesting ideas to mull over.

Enjoy the gun and keep us up to date with what's happening with it

[look no hands]

Now the new spanner in the works MAY be the shortened barrel, all the experiences I've had with chopped BSA barrels is the losing of the choke, which then has always effected accuracy, how long is the barrel?, one reason why I prefer the Mercury/Challenger over the Airsporter is because I'm a carbine freak and being able to use a 10" Lightning barrel makes life a hell of a lot easier when it comes to barrel shorterning and keeping accuracy.

I do hope that I'm just scare mongering and that I'm proved wrong in this case and that someone has just recrowned the end for better accuracy and not lost the choke, I know on some of the older BSA break barrels (and the Airsporters) they had a hollow bit at the end which was supposed to protect the crown from damage but which could in theory be cut off, hopefully this is what's happened.

Once again what is the barrel length?

Pete

[Dan944]

Now the new spanner in the works MAY be the shortened barrel, all the experiences I've had with chopped BSA barrels is the losing of the choke, which then has always effected accuracy, how long is the barrel?, one reason why I prefer the Mercury/Challenger over the Airsporter is because I'm a carbine freak and being able to use a 10" Lightning barrel makes life a hell of a lot easier when it comes to barrel shorterning and keeping accuracy.

I do hope that I'm just scare mongering and that I'm proved wrong in this case and that someone has just recrowned the end for better accuracy and not lost the choke, I know on some of the older BSA break barrels (and the Airsporters) they had a hollow bit at the end which was supposed to protect the crown from damage but which could in theory be cut off, hopefully this is what's happened.

Once again what is the barrel length?

Pete

Hi Pete,

Just measured up and the original barrel length in standard .22 form measures in at 18 inches long, and the new .177 barrel measures in at 16.5 inches long

[clarky]

Not what i meant fella.....i meant that becasue his power levels were almost similar after the barrel swap, there would clearly be little need for different springs as suggested by one poster.
On a different note i thought he did say the thing was a bit more zappy.

The OP did not report a harsher firing cycle

Also, as he's said, getting it on the range properly may (or may not) highlight problems.

If this were the case, then there would be scope for reducing both the first and second stage recoil. This would, however, involve more work and experimentation. Reducing the stroke would make it sweeter. I don't know the swept volume of the Supersport for sure, but, as they're more than capable of producing power levels in excess of our limit, there's a definite option there. Lightening the piston may also help, but that would tend to help with the first stage of recoil and might make the surge worse, which, as has been pointed out, can be the major cause of hold sensitivity. I seem to remember that the TPs are pretty short on these, and I'm not aware of the diameter, but there's probably a little scope to open up the TP slightly, aiding air flow and reducing pressure on the piston face and hence surge.

As you'll know, tuning a springer correctly, any springer, but especially a lighter one in the smaller calibre, is all about the question of balance. Balance in terms of swept volume, TP diameter, spring length, rate etc., piston weight, stroke etc. etc. Get it right and they can be exceptionally sweet.
If the OP is committed to the project and wants to take it further whilst retaining the smaller calibre, there are plenty of options. It all depends how much time, work and money he would be prepared to invest, but the options would definitely be there to explore.

Have fun tweaking!

[clarky]

The OP did not report a harsher firing cycle

Also, as he's said, getting it on the range properly may (or may not) highlight problems.

If this were the case, then there would be scope for reducing both the first and second stage recoil. This would, however, involve more work and experimentation. Reducing the stroke would make it sweeter. I don't know the swept volume of the Supersport for sure, but, as they're more than capable of producing power levels in excess of our limit, there's a definite option there. Lightening the piston may also help, but that would tend to help with the first stage of recoil and might make the surge worse, which, as has been pointed out, can be the major cause of hold sensitivity. I seem to remember that the TPs are pretty short on these, and I'm not aware of the diameter, but there's probably a little scope to open up the TP slightly, aiding air flow and reducing pressure on the piston face and hence surge.

As you'll know, tuning a springer correctly, any springer, but especially a lighter one in the smaller calibre, is all about the question of balance. Balance in terms of swept volume, TP diameter, spring length, rate etc., piston weight, stroke etc. etc. Get it right and they can be exceptionally sweet.
If the OP is committed to the project and wants to take it further whilst retaining the smaller calibre, there are plenty of options. It all depends how much time, work and money he would be prepared to invest, but the options would definitely be there to explore.

Have fun tweaking!

No didnt mean that fella...i was responding to one posters view that they use different mainsprings for varying calibers (being the reason whay .177 is harsher.) They do not. The similar power levels found during his barrel swap out clearly shows there is no need for different springs, at least in this rifle.

[look no hands]

Hi Pete,

Just measured up and the original barrel length in standard .22 form measures in at 18 inches long, and the new .177 barrel measures in at 16.5 inches long

Hi Dan,

Now that has confused me, why just take an inch and a half off the end of a barrel especially if it has a choke on the end of it, I can may be understand the half inch if it had the hollow end barrel to make the crown flush, surely if your going to shorten a barrel then SHORTEN it, all I can suggest is push a pellet up the barrel with a rod and see if you get any resistance from a choke, if no resistance then just test to see what the accuracy is like, I may be just blowing things out of preportions here but I wouldn't want you to blame the rifles accuracy on the firing cycle when it could be down to the barrels accuracy.

Pete

[TonyHolden]

The biggest problem with this thread is that I'm now feeling a great deal of temptation and am wondering if I can get a Supersport in .177 but with a tactical stock, as the one on the BSA webpage looks more and more appealing

[TonyHolden]

Hi Dan,

Now that has confused me, why just take an inch and a half off the end of a barrel especially if it has a choke on the end of it, I can may be understand the half inch if it had the hollow end barrel to make the crown flush, surely if your going to shorten a barrel then SHORTEN it, all I can suggest is push a pellet up the barrel with a rod and see if you get any resistance from a choke, if no resistance then just test to see what the accuracy is like, I may be just blowing things out of preportions here but I wouldn't want you to blame the rifles accuracy on the firing cycle when it could be down to the barrels accuracy.

Pete

Just a thought, but by the time a pellet is about 8-ish inches along a springer barrel it's got as much of a push as it's going to get, cutting off the choke maybe the reason the muzzle velocity is higher than expected...

[Dan944]

Just a thought, but by the time a pellet is about 8-ish inches along a springer barrel it's got as much of a push as it's going to get, cutting off the choke maybe the reason the muzzle velocity is higher than expected...

This does make sence to me. This may be the reason why I havnt lost all that power I and everyone expected????

I also understand what the comment a few posts before was saying about maybe the choke could be the reason that the set up may not be working and may not be the blame of the gun itself or even me to that point.

I have done a few carbine mods myself in the past and I also have cut the choke off a full length 77 last year and did a 9inch ultra carbine mod to it, and recrowned it to find the pellets where all over the place, so I then with all my stuberness not to give up through all my hard work up to then, did a further two more 4mm flush cuts and recrownes Untill it was 3rd time lucky and accuracy was up to my expectations again with accuracy at 30 yards off the bench resting my hand on a bag and the rifle in my palm and the groups I could achieve measured 5mm by 5mm on paper outside with medium wind.

Just to add to the strangeness of this rifle mod going too well, I have to tell everyone that on closer inspection as I said before this barrel seems to have been chopped and recrowned, but the end is by far square, infact I thought that I would correct it if all goes well...but and it's a good BUT.............I finally tested this setup on paper earlier at 20yards and it actually felt not harsher but I worked out what the difference was. It has a very very fast locktime, which ifor me is very welcome as I am known for making longer piston rods to short stroke riffle new or old. And best of all the recoil, seems to be very linier, feels like it comes straight back and fast and that's it.

After 10 shots of zeroing in, I am over the moon that with a bit of tweaking on the trigger, I have managed a 7 shot .22 pellet size one hole group!

I am totally and utterly impressed with the outcome of all this and I am also happy that I have involved you guys along with my journey so far as I am always doing projects but rarely put anything up on here as I go along.

A interesting thing I have realised is in the hold position can make a huge part in gaining tipped springer accuracy. I found a very light shoulder hold and onto my soft cupped palm, a light touching cheek on the cheeckpiece, but here's the interesting bit........ I tried holding my palm very far back right infrint of the trigger guard maybe 2 inches and this felt very strange at first as I used to hold just before the forend screw holes, but soon as I took 3 shots it felt smoother to shoot and more balanced and I began putting a red jsb through the same hole one after the other to the point at 7 I stopped and tried in a different place of my plasterboard and began sticking 4 pellets through the same hole!

To say I was extatic was a understatement, so my wife said come on we need to go now to her mum and dads for dinner, and for once I went with a big smile on my face!

[look no hands]

That's good to hear then, glad it's not effected accuracy, this has indeed turned out very good for you.

Just enjoy shooting it now and try and get the Superstar trigger conversion like I said earlier.

Pete

[TonyHolden]

Pete, if the trigger is as good as on my XL Tac then it may not need any fettling.

[El Garro]

I'm suprised at the power level after the barrel change too.
If I'm the guy with the 9ft/lb gun, I can assure you there wasn't anything wrong with the gun. I may have remembered the actual figures a bit wrong but i simply changed the barrels when the gun was set up and shooting well at .22 . The power did drop but I later fitted a gas ram (.177 to match the full length .177 barrel) and then had to alter the cross pin to reduce the preload on the ram to keep it legal with AA 4.52s.
I also found that fitting the shorter xl barrel brought the power down a tad too but it was a little harsher to shoot.
I'm pretty sure the SS was available in the tactical stock for the export market. I like the feel of the tactical. My last one was a tac with a SS barrel. I sold it when I was skint. Wish I hadn't now.

[look no hands]

Pete, if the trigger is as good as on my XL Tac then it may not need any fettling.

I had a Lightning XL when they first came out and to be honest it wasn't that bad, I think it was just that the trigger itself was made from pressed steel and just seemed to lack any real crispness to it, the Superstar triggers are on a par with the Rekord unit but just seem to break cleaner in my eyes.

Pete