Canadian Airgun Forum

The #1 Community for Airguns in Canada!
It is currently Tue Nov 12, 2019 6:56 am

All times are UTC - 5 hours


The Canadian Airgun Forums are a place for people to discuss and learn about airguns and the airgunning sport in Canada. There are lots of discussions about airguns, airgun accessories, reviews, modification and repair information, airgun events, field target and free classifieds!

 

You need to register before you can post: click the register link to proceed. Before you register, please read the forum rules. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload your own pictures, and access many other special features. Registration is fast, simple, and absolutely free! To start viewing messages, select the forum that you want to visit from the selection below.








Post new topic Reply to topic  [ 4 posts ] 
Author Message
PostPosted: Wed Jan 08, 2014 4:29 pm 
Offline
User avatar

Joined: Sun Jan 09, 2011 8:07 am
Posts: 3320
Location: Central West River Nova Scotia
Today I "attempted" to get my 1740 ie 2240 with .177 barrel, to shoot under 500 FPS. Here are the results. I am not going to post all the numbers. Just too many. First 20 shots 433 fps to 461 fps. second 20 shots.470 fps to 481 fps. third 20 shots. 466 fps to 494 fps. fourth 20 shots. 505 fps 542 fps. fifth 20 shots. 510 fps to 517 fps. Sixth 20 shots. 523 fps to 519 fps. Seventh 20 shots. 553 fps to 608 fps. Eighth 20 shots. 609 fps to 638 fps. Ninth 20 shots. 646 fps to 668 fps. Tenth 20 shots. 617 fps to 668 fps Eleventh 20 shots. 652 fps to 658 fps. Twelfth 20 shots. 669 fps to 623 fps. Thirteenth 20 shots. 646 fps to 547 fps. Fourteenth 20 shots. 542 to 426 fps. Total 240 shots powerful enough to kill a starling. on one fill 55 cc reservoir (Hi Pac with 2 extensions) The first 60 shots were under the 500 fps limit the next 60 shots rose to 600 fps then plateaued in the 600 fps range for the next 80 shots, then gradually dropped to under 500 fps for the last 40 shots. The string was gradual all the way up and down, with the occasional "one shot" spike or drop of only 20 to 40 fps. this I blame on the pellet.
It seems in order to stay under the 500 fps mark I would have to fill the gun to only 1200 to 14oo psi. otherwise the slingshot hammer setup is unable to open the valve enough to get close to 500 fps without going over as the pressure drops. I will have to sacrifice shot count to stay under the legal 500 fps mark. Even so I should be able to get well over 100 shots . When I filled the gun there was 500 psi left. The highest fps shot was 669 fps the lowest was 433 fps. an average of 551 fps. So that,s a 55 CC reservoir 240 shots at an avg of 551 fps. I have no clue how to figure the energy consumption per shot. Anybody care to share.

_________________
If I had only one wish, it would be to be able to "unsay" things.


Top
 Profile  
 
PostPosted: Wed Jan 08, 2014 4:57 pm 
Offline
User avatar

Joined: Sun Jan 09, 2011 8:07 am
Posts: 3320
Location: Central West River Nova Scotia
joe hickey wrote:
Today I "attempted" to get my 1740 ie 2240 with .177 barrel, to shoot under 500 FPS. Here are the results. I am not going to post all the numbers. Just too many. First 20 shots 433 fps to 461 fps. second 20 shots.470 fps to 481 fps. third 20 shots. 466 fps to 494 fps. fourth 20 shots. 505 fps 542 fps. fifth 20 shots. 510 fps to 517 fps. Sixth 20 shots. 523 fps to 519 fps. Seventh 20 shots. 553 fps to 608 fps. Eighth 20 shots. 609 fps to 638 fps. Ninth 20 shots. 646 fps to 668 fps. Tenth 20 shots. 617 fps to 668 fps Eleventh 20 shots. 652 fps to 658 fps. Twelfth 20 shots. 669 fps to 623 fps. Thirteenth 20 shots. 646 fps to 547 fps. Fourteenth 20 shots. 542 to 426 fps. Total 240 shots powerful enough to kill a starling. on one fill 55 cc reservoir (Hi Pac with 2 extensions) The first 60 shots were under the 500 fps limit the next 60 shots rose to 600 fps then plateaued in the 600 fps range for the next 80 shots, then gradually dropped to under 500 fps for the last 40 shots. The string was gradual all the way up and down, with the occasional "one shot" spike or drop of only 20 to 40 fps. this I blame on the pellet.
It seems in order to stay under the 500 fps mark I would have to fill the gun to only 1200 to 14oo psi. otherwise the slingshot hammer setup is unable to open the valve enough to get close to 500 fps without going over as the pressure drops. I will have to sacrifice shot count to stay under the legal 500 fps mark. Even so I should be able to get well over 100 shots . When I filled the gun there was 500 psi left. The highest fps shot was 669 fps the lowest was 433 fps. an average of 551 fps. So that,s a 55 CC reservoir 240 shots at an avg of 551 fps. I have no clue how to figure the energy consumption per shot. Anybody care to share.

looks like 6.25 psi per shot avg.

_________________
If I had only one wish, it would be to be able to "unsay" things.


Top
 Profile  
 
PostPosted: Wed Jan 08, 2014 9:47 pm 
Offline
User avatar

Joined: Sun Feb 10, 2013 1:16 pm
Posts: 1787
Hi Joe,

If you have a spare transfer port you could experiment with reducing the diameter. Smaller ports can definitely drop the fps, although my impression was that they do so simply by making the gun less efficient. However it might help to flatten the curve and let you keep the amazing shot count without going over limit.

EDIT - OK, I may have this wrong. Eric just corrected me in another thread that the smaller transfer ports give better performance in 177 air based guns. When I did my tests I was using CO2, so maybe that explains the different results. Sorry for any confusion I caused.

Jim


Top
 Profile  
 
PostPosted: Thu Jan 09, 2014 12:02 am 
Offline
User avatar

Joined: Sun Jan 09, 2011 8:07 am
Posts: 3320
Location: Central West River Nova Scotia
EverHopeful wrote:
Hi Joe,

If you have a spare transfer port you could experiment with reducing the diameter. Smaller ports can definitely drop the fps, although my impression was that they do so simply by making the gun less efficient. However it might help to flatten the curve and let you keep the amazing shot count without going over limit.

EDIT - OK, I may have this wrong. Eric just corrected me in another thread that the smaller transfer ports give better performance in 177 air based guns. When I did my tests I was using CO2, so maybe that explains the different results. Sorry for any confusion I caused.

Jim

I have 4 different size tp, s. I'm using the smallest one. Ideally a rva would solve the problem. My home made one broke. I will buy a proper one soon.

_________________
If I had only one wish, it would be to be able to "unsay" things.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 4 posts ] 

All times are UTC - 5 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
News News Site map Site map SitemapIndex SitemapIndex RSS Feed RSS Feed Channel list Channel list

Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group

phpBB SEO