Back to the open sight

[u_vaste]

HI Guys,
Its been quite long time I have posted anything,I was just reading forum without longing.
lets continue my old story....
I had replaced front sight and rear both few months back, now a days you get plastic/fiber front sight as precihole and back sight without notch selection i.e. fixed notch "u" type. with this combination I could get some elevation but sight windage still needed to keep extreme left.
As mentioned the power of AR dropped down extremely low my adroid chrono recorded 151fps max only, I do not know how much I could trust but I had six readings they are between 149-151. so I had ordered IHP tune kit from TTI but unfortunately their key resource fallen seriously ill so they returned my money still asked them to take some time But it seems they stopped all orders.
Now I did not used my AR for more than three months I wish to open and service it but without spares handy I know it just lie in peaces so I did not opened it.
well guys can any one help with IHP tune kit.

Uv

[estousandy]

Have you opened it up yet? Mine is in the works now. It's sad the TTI IHP tune kit is available nomore.

[Basu]

Dear Uv,
I presume that you ard getting 495 fps with MS Flat head.
If that be so , you shift to some lighter pellets and things will improve.
MSFH delivers only 435 fps in my gun but with some other pellets it goes upto 650 fps as per cronoconnect.

Basu

[u_vaste]

Basu,

I did not opened my IHP so far , I am planing to open this week end. as I said earlier my android crono shows max 151 fps and I do not want to use lighter pellet I have Gsmith and other more than 1K pellets available with me , which gives good accuracy. I had tried lighter pellets before (initially) and it gave me spread all over target.

Uv

[u_vaste]

I opened My IHP yesterday , I guess I need new piston seal, breech seal and trigger. Posting pics here experts /experience people let me know what do you think seeing pics also please suggests on getting the spares and lube.



Piston seal warn out and even piston had friction with chamber




I guess Piston hitting for longer time to end of chamber because of worn out seal.

What do you think of spring guide



spring slightly bent but no damage




Breech seal completely worn out at top friction mark on top of breach seal




trigger has huge play at rivet


Regards
Uv

[Basu]

Dear u_vaste,
From the photos ,nothing looks wrong as such .
The reasons for velocity loss may be the piston seal ruptured from inside the skirt and that can not be seen in photo ,if you wash them clean it will be visible. The breech seal is always a bigger culprit ,you need to use new one ,preferably rubber one.
The spring may have lost recoiling power.
The trigger should not be any issue as they are like that only.
Too much moly or grease may cause problem. Do wash and tune again ,hope you will get back power.

Basu

[Basu]

Dear u_vaste,
From the photos ,nothing looks wrong as such .
The reasons for velocity loss may be the piston seal ruptured from inside the skirt and that can not be seen in photo ,if you wash them clean it will be visible. The breech seal is always a bigger culprit ,you need to use new one ,preferably rubber one.
The spring may have lost recoiling power.
The trigger should not be any issue as they are like that only.
Too much moly or grease may cause problem. Do wash and tune again ,hope you will get back power.

Basu

[bennedose]

Change your spring and piston seal. That spring may need retirement with pension. Piston friction with side exists in all air rifles and I am personally not convinced that it is necessary to remedy that although I know people do recommend it. Sanding it will make it slide smoothly, but the extra velocity due to smooth movement of piston does not necessarily mean more power. Besides - the close fit of piston along with some lubricant may actually help prevent/slow down an air leak that gets behind the seal. Over sanding may spoil that IMO.

[brihacharan]

Both Basu & Bennedose have diagnosed the problem correctly...
The only hassle being in getting a good gunsmith / knowledgeable person to tune the AR...
Briha

[u_vaste]

Guys thank for your view/suggestions.

@brihaji -- Agree with you but I am planning to do it myself , I have read many post here and other forums , goggle and so on and got some experience on maintaining machines so pretty confident. besides its good ways to gain knowledge and experience. Any Idea where I can get rubber breech seal , I read here on forum that new IHP using them. I had ordered tune kit from TTI but unfortunately they stopped their operations due to key member expired. another I know to get spares from is "airgunindia" who does not have good reputation at list in piston seal specially(read here on forum). I guess, you are based out of Mumbai can you suggest where I can get piston seal breach seal and spring. I know there are post of making breach seals but I intend to get ready made. M/s Hassanand Hemandas &Co keeps springs but no seals.

will keep posting on progress

Uv

[Basu]

Dear Uv,
Please see this thread.

http://indiansforguns.com/viewtopic.php?f=22&t=21356

You may get same piston seal at IHP company, that is not bad at all, cost 50/- per ps.


Basu

[u_vaste]

Dear Uv,
Please see this thread.

http://indiansforguns.com/viewtopic.php?f=22&t=21356

You may get same piston seal at IHP company, that is not bad at all, cost 50/- per ps.


Basu

Thanks basu, I have gone through this post and others as well, I am keeping this as last resort , If I did not get original breech seal. further I checked piston seal its OD is lesser than chambers ID I do not know how much that makes difference but on power but, I surely feel to change it. see pics below.





Uv

[Basu]

Dear Uv,
It seems that the piston seal depreciated over time.
0.4 mm gap is little too high to cover the bore even after expansion when compressed.
I think the receiver requires honing to incease life of seal.
Get a new seal , assemble and check the velocity.
Even after that if there is dno change in FPS ,get a new spring.

Basu

[bennedose]

Basuda is right. That piston seal must be changed. It should be a snug fit which cannot happen if the OD of the seal is less than that of the chanber.

I must compliment you on your ability to post excellent and relevant images.