Inconsistent TXHC

[Hellequin]

I've a TX200HC in .177 cal which has been tuned and given the 22mm skirtless piston treatment, running (I'm told) around 84mm stroke.

The rifle is lovely but slightly low on power and very inconsistent. Last chrono string (30 shots) started with a 10.9/763fps then an 11/768fps but afterwards dropped- 10.7ft/lb down to 10.2, then into the 9's with a low of 9.5 then back up to around 9.9ft/lb.
High fps was 768 and low was 714. I'd expect better than that from an el cheapo Gamo or Hatsan!

Now, the tuner had told the previous owner it would need running in & then trying with some recommended pellets (JSB) and I've now done this.

My question, before I approach the tuner for his advice, is are there any basics I need to check that might solve it? I'm thinking possibly breech seals?

I'm not too worried about power levels. I'd like a little more, nearer 11ft/lb but it's only used for plinking targets so I'm more interested in consistency. Years ago I had a tuned HW80K running on FAC at near 20ft/lb which was ultra consistent with a spread of just 3 or 4fps over a 30 shot string. Really I'd expect similar from this TX.

Any advice welcome, and yes I know 'contact the tuner' is best bet but I just want to cover any basics before going down the 'your work isn't great' route...

Cheers

[angrybear]

Maybe it just doesn't like the pellets, try others & for the purpose of the test, weigh them so you know they're within 0.1-0.2gn.

If it's still all over the place, speak to the tuner but don't go in saying his work is no good,
just explain that it's inconsistent & ask for it to be checked over in case something's failed inside.

[Hellequin]

Maybe it just doesn't like the pellets, try others & for the purpose of the test, weigh them so you know they're within 0.1-0.2gn.

If it's still all over the place, speak to the tuner but don't go in saying his work is no good,
just explain that it's inconsistent & ask for it to be checked over in case something's failed inside.

I wasn't seriously going to go in with "your work sucks". I'm a blunt Yorkshireman but do have a little diplomacy in me

I have tried different pellets & the results are similar, hence wondering if it might be iffy breech seals.

I'm sure most folk could guess who has done the work and he has a very good reputation, especially with the TX. I just want to make sure I've covered any potential simple fixes before I ask him to take a proper look.

[NickG]

Wouldn't hurt to change the breech seals, they are relatively cheap, however small diameter tunes can be pellet sensitive, however I wouldn't expect inconsistency, just different power with different brand/size , you probably need to talk to the maker.

[Hellequin]

Wouldn't hurt to change the breech seals, they are relatively cheap, however small diameter tunes can be pellet sensitive, however I wouldn't expect inconsistency, just different power with different brand/size , you probably need to talk to the maker.

Thanks Nick. I've ordered some breech seals just to try first as I'd rather not bother him if it's something that simple. If it doesn't do the trick I'll drop him a line.

As I said, I'm not too fussed that the power is a little low, I just want it to be consistent.

[tinbum]

Check for debris ahead of the compression tube, a pellet dropped there can be hammered into a thin veneer that can reduce it’s ability to seal.

Failing that, try contacting the tuner. I’m sure he’ll tell you what you are doing wrong.

[lonewolf]

well when i tune a gun i fire many shots over a chrono first to set the power that is required and also to check the shot consistency
so i am supprised that a tuner has returned your gun in that condition,my advice change the 2 breech seals has they could of been overlooked by the tuner and if you want to alter the power just add a shim washer size internal 15mm outside 22mm, a 2mm thick washer will increase the velocity by abought 15 ftps

[prosport.177]

I wasn't seriously going to go in with "your work sucks". I'm a blunt Yorkshireman but do have a little diplomacy in me

I have tried different pellets & the results are similar, hence wondering if it might be iffy breech seals.

I'm sure most folk could guess who has done the work and he has a very good reputation, especially with the TX. I just want to make sure I've covered any potential simple fixes before I ask him to take a proper look.

Get hold of the original tuner who did conversion .. I am sure they will sort out the issue . If it is who we think it is he's over on face ache pages get hold of him... reading some posts over there might shed some light on it for you..
Cheers

[Hellequin]

Check for debris ahead of the compression tube, a pellet dropped there can be hammered into a thin veneer that can reduce it’s ability to seal.

Failing that, try contacting the tuner. I’m sure he’ll tell you what you are doing wrong.

I'll give it a look, thanks Nick. All I've done so far is put pellets through though, and I'm pretty sure even I can't cock that up 🤣

well when i tune a gun i fire many shots over a chrono first to set the power that is required and also to check the shot consistency
so i am supprised that a tuner has returned your gun in that condition,my advice change the 2 breech seals has they could of been overlooked by the tuner and if you want to alter the power just add a shim washer size internal 15mm outside 22mm, a 2mm thick washer will increase the velocity by abought 15 ftps

Thanks mate. I'm not the first owner after the work was done and I'm not surprised at the low ish power as, to my knowledge, he likes to set them in the low to mid 10ft/lb range, which for this rifle I'd be happy with anyway.

I'm surprised it's so inconsistent shot to shot though, with good quality pellets too. I'm sure if I contacted him he'd be very helpful so I'm really not having a dig. As I've already said, if there's something simple I can do to sort it then I'm happy to do that first so I'll definitely give the breech seals a go.

I've never stripped a TX but compared to the numerous HW's & BSA's I've had apart, they seem pretty straightforward so I might just open it up for a look check there's nowt obviously broken.

[Hellequin]

Get hold of the original tuner who did conversion .. I am sure they will sort out the issue . If it is who we think it is he's over on face ache pages get hold of him... reading some posts over there might shed some light on it for you..
Cheers

Ah good old BookFace... I'll have a look cheers

[Edtwozeronine]

When I recently gave my TX200. 22 back to our clubs gunsmith (needed the safety replacing) he tested it out of due diligence and it's banging out 11.5 ft/lbs with Exacts, a pellet I don't personally use as a plinker.

My point being they can put out the power when they're running right.

[clipper]

If it is a TL (he of FB fame) 22mm skirtless piston I have the same in my full length TX .177, and have found QYS to be the best

I tried all the different headsizes of JSB Exact, AA Diabolo, FTT, RWS, in the rifle as standard, when it had a TbT short stroke kit, and in its current state, and nothing even came close to the consistent FPS, grouping, and accuracy of the QYS Streamlined 8.48gr 4.50mm head

Mine is running around 10.5ft/lb, standard AA spring, no preload washers.... it did take three strip and rebuilds to get the stroke length correct but it is now almost recoilless, completely impervious to hold (although I still wouldn't clamp it in a rest like a PCP!), and single figure FPS variance

Give TL a call when you have enough time to absorb everything he will tell you.. the man likes to talk! My best guess with inconsistency like you describe would be breach seals, excessive amounts of grease/lube or a spring that it is out of shape, poorly dressed, or has been heated and squashed

[Hellequin]

If it is a TL (he of FB fame) 22mm skirtless piston I have the same in my full length TX .177, and have found QYS to be the best

I tried all the different headsizes of JSB Exact, AA Diabolo, FTT, RWS, in the rifle as standard, when it had a TbT short stroke kit, and in its current state, and nothing even came close to the consistent FPS, grouping, and accuracy of the QYS Streamlined 8.48gr 4.50mm head

Mine is running around 10.5ft/lb, standard AA spring, no preload washers.... it did take three strip and rebuilds to get the stroke length correct but it is now almost recoilless, completely impervious to hold (although I still wouldn't clamp it in a rest like a PCP!), and single figure FPS variance

Give TL a call when you have enough time to absorb everything he will tell you.. the man likes to talk! My best guess with inconsistency like you describe would be breach seals, excessive amounts of grease/lube or a spring that it is out of shape, poorly dressed, or has been heated and squashed

Thanks clipper, I'm hopeful the breech seals will sort it. Yours sounds awesome & I'd be happy with 10.5 in this rifle, I might give some QYS a try too.

[MrGreengrass]

Breech seal, piston seal or both.
Probably the easiest springer in the world to service.
I have just done a new to me .22 HC.
It was at 9ft lb.
Took out an extended nose piston seal thingy...no likey.
New , new breech o ring and kept the same spring in it, a bit of bumlube here and there.
11.5 and very consistent.
Just ordered a few more Britseals as spares as I have x4 TX and x2 Prosports.

[Hellequin]

An update to this...

I've stripped the TX this morning. I've found two possible issues:

1. There was only one o-ring breech seal- isn't there supposed to be two fitted?

2. There's another o-ring which sits in a recess in front of the breech seals. It's wider so doesn't look the same. It looks chewed up/split.

I've added a link with images, arrow pointing to the chewed o-ring. Any advice appreciated.


https://ibb.co/album/5YbCFm