Shooting the breeze Dowry Hill FTC  
Go Back   Shooting the breeze > The Chat > General Airgun Chat

General Airgun Chat Chat and banter that doesn't fit anywhere else...

Reply
 
Thread Tools Display Modes
  #31  
Old 18th October 2016, 04:11 PM
Brian.Samson's Avatar
Brian.Samson Brian.Samson is offline
Allowed in Sales
 
Join Date: Jun 2009
Member of: Pontefract, Doncaster Airgun Range
Location: Doncaster
Posts: 2,476
Default

Quote:
Originally Posted by C.Eaton View Post
If it's the hole under the action I seem to remember someone saying a while ago that this was the vent hole for the hammer which makes sense if think about it; impede it and the hammer can't move as readily as it would like so affects performance and all that.
That makes sense - so long as the foam allows enough air to flow through it shouldn't affect performance in theory. I would imagine AA would have tested that before fitting the foam to new FTP's.

I'll give it a test myself though just in case.
Reply With Quote
  #32  
Old 18th October 2016, 04:25 PM
DYNO DAVE DYNO DAVE is offline
Senior Member
 
Join Date: Jan 2009
Member of: Dunfermline
Location: Dalgety bay fife
Posts: 359
Default Ftp

The air that people are feeling is escapeing down the stem of the firing valve , absolutely normal on airarms guns , what happens when you block or ubstruc the hole is the air will affect the hammer the air has to go some were and as long as it's consistent nothing in the way all is fine I may be wrong but the foam is just to keep dust and crap out of there or to dampen the blast ether way it's normal just don't restrict the hole .
Regards Dave
Reply With Quote
  #33  
Old 18th October 2016, 04:59 PM
plattitude's Avatar
plattitude plattitude is offline
Senior Member
 
Join Date: Oct 2009
Member of: Anston
Location: sheffield
Posts: 326
Default

Quote:
Originally Posted by DYNO DAVE View Post
The air that people are feeling is escapeing down the stem of the firing valve , absolutely normal on airarms guns , what happens when you block or ubstruc the hole is the air will affect the hammer the air has to go some were and as long as it's consistent nothing in the way all is fine I may be wrong but the foam is just to keep dust and crap out of there or to dampen the blast ether way it's normal just don't restrict the hole .
Regards Dave
Thats why I put a vent hole in my extended rod as restricting the vent hole influences the hammer.

Paul
Attached Images
File Type: jpg ham 002.jpg (54.7 KB, 68 views)
Reply With Quote
  #34  
Old 18th October 2016, 06:05 PM
Ewan's Avatar
Ewan Ewan is offline
Ewan
 
Join Date: Sep 2015
Member of: Iden Ferns
Location: Hastings
Posts: 101
Default

[QUOTE=vinny;248558]
Quote:
Originally Posted by Ewan View Post
One thing you should watch out for though is if you use the Hamster extension rods.
Not sure if anyone else has noticed this but i'll explain.

When I bought my extension rods from Bonds Airgun Spares I had to trim them down as I shoot HFT, having made centre to barrel from bottom of hamster was in line with HFT rules I did get some comments at my last comp, I even offered for it to be measured but I was told 'na don't worry', anyway as soon as I got home I re measured them & yes they were too long, by 1mm, very sorry about this btw.

I have now removed them both but while at the club at the weekend I noticed if the hamster was pushed all the way up it made the noise from the stripper change considerably also changed POI.

The rifle seemed to produce a spluttering noise but once the Hamster was pulled out a little, no contact made the rifle a lot quitter & POI improved, so be careful when positioning the Hamster so it does not make contact with the action inside.

One rod will hit metal the other hits the small foam pad (put there to deaden the air blast from the 'air release hole' from the reg I think), anyway just a useless bit of info for you.

If the rifle is running well you should not even have to check zero each week as it seems to keep it bang on, not allowing for any knocks you may give it though in transit :-)[/QUOTE

hmm little foam pad, never had this on mine but had noticed on another one, if its the one I think it is any attempt to block its going to seriously alter the velocity, theres been s fair few comments about it on here already, tbh the air coming outs going to blow any thing out the way , stick it over a chrono with your finger over it , youll get a good 50 fps difference .
Ok , just taken mine out of the stock , theres about 10mm clearance difference between the front and rear , are your posts that different in lenght ? ]
My posts are of equal length Vinny, as were the two extension rods as well.

What have I started :-), thinking about all this the noise I was hearing was from the top of the extension rod blocking the venting hole & creating a rasping (farty) sound but it DID effect performance, don't ask me why but POI did shift.

The foam was placed there by AA because some people were reporting air 'escaping' from underside & user's were feeling it on their hands, quite rightly they thought the FTP was a baddun & called AA. The foam is meant to 'break' the noise up & muffle it (think that's what I read when looking at buying the rifle I the first place). Bit of an engineering 'miss' putting the hole right on top of the hamster rods though I think :-)

It is without doubt a brilliant rifle, I love it, it just don't miss. I now have the tiny part of the butt hook pointing forwards (the little section at the bottom) this gives a good platform on my knee when doing kneelers the 'unorthadox' way.

All of the sponge talk did get me remembering I was having a right old time on the chrony a few times with very 'wild' fps results & I did have the extension rods fitted & pushed up .

The things you learn eh!
__________________
FTP900
ISP Airstream MK3 by Shaun Hill in a GC stock
S400F
AR5s
Reply With Quote
  #35  
Old 18th October 2016, 06:33 PM
Tench's Avatar
Tench Tench is offline
WHFTA World Champion 2016.
 
Join Date: Sep 2009
Location: derby
Posts: 1,502
Default

AA in their wisdom (?) don't use a gland seal on the firing valve stem, this causes air to leak down the valve stem when the transfer port is under pressure during the firing cycle. I think this hole also allows air to escape during the forward travel of the hammer. If this is the case blocking the hole will slow the hammer and reduce the power. Blocking the hole will also cause the air escaping down the valve stem to blow the hammer back causing a double (or more) tap on the valve, this is most likely what people hear when they say the sound of the gun changes. Basically it all comes down to a design that cuts corners, unfortunately loads of different makes of rifles are made without stem seals.

With the exception of BSA I cant think of another maker that uses valve stem seals on all their designs?
__________________
HFT, for people with only 2 buttucks!

VooDoo TwoTwo The next chapter.
Reply With Quote
  #36  
Old 18th October 2016, 06:48 PM
RobF's Avatar
RobF RobF is offline
My Empire of Dirt
 
Join Date: Mar 2010
Member of: Southampton Buccaneers, Parkstone, South Dorset
Location: Poole, Dorset
Posts: 10,292
Default

Walther don't. But not sure how much leaks down there and the hammer is pretty heavy. I do know air will leak out of the hammer stop and the pin hole if that wedge is removed, but it's not a lot, gaffa tape is enough to stop it and it doesn't get blown off.
__________________
BFTA/NSRA County Coach
CSFTA Chairman/BFTA Rep
Reply With Quote
  #37  
Old 18th October 2016, 07:20 PM
vinny's Avatar
vinny vinny is offline
WHFTA 2015 World Champion
 
Join Date: Mar 2014
Member of: M.A.D
Location: essex
Posts: 622
Default

Quote:
Originally Posted by Tench View Post
AA in their wisdom (?) don't use a gland seal on the firing valve stem, this causes air to leak down the valve stem when the transfer port is under pressure during the firing cycle. I think this hole also allows air to escape during the forward travel of the hammer. If this is the case blocking the hole will slow the hammer and reduce the power. Blocking the hole will also cause the air escaping down the valve stem to blow the hammer back causing a double (or more) tap on the valve, this is most likely what people hear when they say the sound of the gun changes. Basically it all comes down to a design that cuts corners, unfortunately loads of different makes of rifles are made without stem seals.

With the exception of BSA I cant think of another maker that uses valve stem seals on all their designs?
Thanks Si , I thought there was more to it than just the hammer pushing the air, I did check 20 pages of your posts before pm ing you
__________________
H.G.H , aspiring to spring power

FTP900 MTC connect,Welhamanium internals -sorted
HFT500, ACZ stock MTC connect
TX200 Mk3 CS1000 stock, hawke vantage sf , Nick G internals
Steyr ?, maybe , they cant all be wrong?
Reply With Quote
  #38  
Old 18th October 2016, 08:59 PM
henryc henryc is offline
Member
 
Join Date: Jan 2015
Location: rotherham
Posts: 21
Default

I wa s pleased to note comments about this 'leak' when I told a couple of blokes at my club that when I dry fired mine out of the stock I felt a draught they said their's didn't and mine was faulty = even though it shoots well,
Reply With Quote
  #39  
Old 19th October 2016, 12:02 AM
Brian.Samson's Avatar
Brian.Samson Brian.Samson is offline
Allowed in Sales
 
Join Date: Jun 2009
Member of: Pontefract, Doncaster Airgun Range
Location: Doncaster
Posts: 2,476
Default

Quote:
Originally Posted by Tench View Post
AA in their wisdom (?) don't use a gland seal on the firing valve stem, this causes air to leak down the valve stem when the transfer port is under pressure during the firing cycle. I think this hole also allows air to escape during the forward travel of the hammer. If this is the case blocking the hole will slow the hammer and reduce the power. Blocking the hole will also cause the air escaping down the valve stem to blow the hammer back causing a double (or more) tap on the valve, this is most likely what people hear when they say the sound of the gun changes. Basically it all comes down to a design that cuts corners, unfortunately loads of different makes of rifles are made without stem seals.

With the exception of BSA I cant think of another maker that uses valve stem seals on all their designs?
What do you think of the AA solution of fitting a fairly low density foam block over the hole? Keep it on or take it off?
Reply With Quote
  #40  
Old 19th October 2016, 08:00 AM
vinny's Avatar
vinny vinny is offline
WHFTA 2015 World Champion
 
Join Date: Mar 2014
Member of: M.A.D
Location: essex
Posts: 622
Default

Quote:
Originally Posted by Brian.Samson View Post
What do you think of the AA solution of fitting a fairly low density foam block over the hole? Keep it on or take it off?
I think AA would have been wise to made a statement in their handbook that this air escape is normal and save themselves all this doubt from buyers
__________________
H.G.H , aspiring to spring power

FTP900 MTC connect,Welhamanium internals -sorted
HFT500, ACZ stock MTC connect
TX200 Mk3 CS1000 stock, hawke vantage sf , Nick G internals
Steyr ?, maybe , they cant all be wrong?
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT. The time now is 07:20 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2016, Jelsoft Enterprises Ltd.
shooting-the-breeze.com Skin design and concept by Attitude